Hans-Petter Hersleth

• Hammerstad, Marta; Steinvik, Erlend & Hersleth, Hans-Petter (2025). The methyltransferase NmbA methylates the low-molecular weight thiol bacillithiol, and displays a specific structural architecture. Redox Biology. 88. doi: 10.1016/j.redox.2025.103937. Fulltekst i vitenarkiv Vis sammendrag

  Low-molecular-weight (LMW) thiols maintain the cellular redox balance and protect cells against reactive species, heavy metals, toxins, and antibiotics. Despite having similar metabolic functions, structurally distinct LMW thiols are widespread in nature, with bacillithiol (BSH) being the predominant LMW thiol in bacteria. The LMW thiol N-methyl-BSH (N-Me-BSH) has been identified in the green sulfur bacterium Chlorobaculum tepidum, revealing the presence of a putative S-adenosyl-l-methionine (SAM)-dependent methyltransferase (MT), NmbA, which could catalyze the final biosynthetic step of N-Me-BSH. In this study, we report biochemical evidence for NmbA's specific function as an MT of the N-atom of the BSH cysteine moiety. We also present the crystal structure of NmbA, confirming that NmbA is a Class I SAM-dependent MT, however, displaying a unique three-dimensional architecture that differs from those of other natural product MTs (NPMTs). The NmbA active site has a narrow molecular basket structure resulting from an unusual organization of the variable Cap domain, and our docking calculations suggests that it can specifically accommodate the BSH substrate. Our research provides a valuable overview of the phylogenetic distribution of N-Me-BSH in bacteria, alongside essential functional and structural insight into a new class of N-directed NPMTs. These findings contribute to the field of SAM-dependent MTs and may allow for targeting distinct bacterial defense mechanisms involving LMW thiols with potential environmental, biotechnological, and medical implications.

• Schroer, Lisa; Weirich, Sara; Hammerstad, Marta; Hersleth, Hans-Petter; Grønsberg, Ida Andrietta & Hagen, Lars [Vis alle 11 forfattere av denne artikkelen] (2025). Orthologues of the human protein histidine methyltransferase METTL9 display distinct substrate specificities. Journal of Biological Chemistry. ISSN 0021-9258. 301(7). doi: 10.1016/j.jbc.2025.110318. Fulltekst i vitenarkiv Vis sammendrag

  The human (Homo sapiens; Hs) methyltransferase (MTase) METTL9 is the first enzyme shown to generate 1-methylhistidine (π-methylhistidine) in proteins. METTL9 preferentially methylates an alternating histidine (HxH) motif, where “x” is a small, uncharged amino acid, and multiple substrates have been identified. Putative METTL9 orthologues are found in most eukaryotes, and we have here investigated the activity of such enzymes from several species, representing all five eukaryotic supergroups. The majority of the tested enzymes demonstrated in vitro MTase activity on the prototype HsMETTL9 substrates ARMC6 and DNAJB12. We also detected protein methylation activity of the Caenorhabditis elegans METTL9 which had previously been suggested to be a DNA MTase. However, METTL9 from the fruit fly (Drosophila melanogaster; Dm) and the picoplankton Ostreococcus tauri (Ot) displayed distinct substrate specificities, differing from each other and from that of HsMETTL9. These differences were observed when recombinant proteins and short peptides were used as METTL9 substrates. To further analyze substrate specificity, we used peptide arrays to systematically replace the “x” residue and the residues flanking the HxH motif in a substrate peptide. This revealed varying degrees of tolerance among the METTL9 orthologues (Hs > Dm > Ot) for substitutions at these positions. Our results show that the METTL9 orthologues, although requiring an HxH target site, have evolved different substrate specificities, likely due to differing biologically relevant substrates in the respective organisms. Furthermore, we solved the X-ray structure of OtMETTL9, revealing several differences from the previously published HsMETTL9 structures that may explain its distinct substrate specificity.

• Fernandez, Javier Gutierrez; Hersleth, Hans-Petter & Hammerstad, Marta (2024). The crystal structure of myco­thiol di­sulfide reductase (Mtr) provides mechanistic insight into the specific low-molecular-weight thiol reductase activity of Actinobacteria. Acta Crystallographica Section D: Structural Biology. 80(3), s. 181–193. doi: 10.1107/S205979832400113X. Fulltekst i vitenarkiv Vis sammendrag

  Low-molecular-weight (LMW) thiols are involved in many processes in all organisms, playing a protective role against reactive species, heavy metals, toxins and antibiotics. Actinobacteria, such as Mycobacterium tuberculosis, use the LMW thiol mycothiol (MSH) to buffer the intracellular redox environment. The NADPH-dependent FAD-containing oxidoreductase mycothiol disulfide reductase (Mtr) is known to reduce oxidized mycothiol disulfide (MSSM) to MSH, which is crucial to maintain the cellular redox balance. In this work, the first crystal structures of Mtr are presented, expanding the structural knowledge and understanding of LMW thiol reductases. The structural analyses and docking calculations provide insight into the nature of Mtrs, with regard to the binding and reduction of the MSSM substrate, in the context of related oxidoreductases. The putative binding site for MSSM suggests a similar binding to that described for the homologous glutathione reductase and its respective substrate glutathione disulfide, but with distinct structural differences shaped to fit the bulkier MSSM substrate, assigning Mtrs as uniquely functioning reduc- tases. As MSH has been acknowledged as an attractive antitubercular target, the structural findings presented in this work may contribute towards future anti- tuberculosis drug development.

• Hammerstad, Marta; Rugtveit, Anne Kristine; Dahlen, Sondov Åsmundson Braathen; Andersen, Hilde Kristin & Hersleth, Hans-Petter (2023). Functional Diversity of Homologous Oxidoreductases—Tuning of Substrate Specificity by a FAD-Stacking Residue for Iron Acquisition and Flavodoxin Reduction. Antioxidants. 12(6). doi: 10.3390/antiox12061224. Fulltekst i vitenarkiv Vis sammendrag

  Although bacterial thioredoxin reductase-like ferredoxin/flavodoxin NAD(P)+ oxidoreduc- tases (FNRs) are similar in terms of primary sequences and structures, they participate in diverse biological processes by catalyzing a range of different redox reactions. Many of the reactions are critical for the growth, survival of, and infection by pathogens, and insight into the structural basis for substrate preference, specificity, and reaction kinetics is crucial for the detailed understanding of these redox pathways. Bacillus cereus (Bc) encodes three FNR paralogs, two of which have assigned distinct biological functions in bacillithiol disulfide reduction and flavodoxin (Fld) reduction. Bc FNR2, the endogenous reductase of the Fld-like protein NrdI, belongs to a distinct phylogenetic cluster of homologous oxidoreductases containing a conserved His residue stacking the FAD cofactor. In this study, we have assigned a function to FNR1, in which the His residue is replaced by a conserved Val, in the reduction of the heme-degrading monooxygenase IsdG, ultimately facilitating the release of iron in an important iron acquisition pathway. The Bc IsdG structure was solved, and IsdG-FNR1 interactions were proposed through protein–protein docking. Mutational studies and bioinformatics analyses confirmed the importance of the conserved FAD-stacking residues on the respective reaction rates, proposing a division of FNRs into four functionally unique sequence similarity clusters likely related to the nature of this residue.

• Shoor, Marita; Gudim, Ingvild; Hersleth, Hans-Petter & Hammerstad, Marta (2021). Thioredoxin reductase from Bacillus cereus exhibits distinct reduction and NADPH-binding properties. FEBS Open Bio. 11(11), s. 3019–3031. doi: 10.1002/2211-5463.13289. Fulltekst i vitenarkiv Vis sammendrag

  Low molecular weight (low Mr) thioredoxin reductases (TrxRs) are homodimeric NADPH-dependent dithiol flavoenzymes that reduce thioredoxins (Trxs) or Trx-like proteins involved in the activation networks of enzymes, such as the bacterial class Ib ribonucleotide reductase (RNR). During the last few decades, TrxR-like ferredoxin/flavodoxin NADP+ oxidoreductases (FNRs) have been discovered and characterized in several types of bacteria, including those not encoding the canonical plant-type FNR. In Bacillus cereus, a TrxR-like FNR has been shown to reduce the flavodoxin-like protein NrdI in the activation of class Ib RNR. However, some species only encode TrxR, and lack the homologous TrxR-like FNR. Due to the structural similarity between TrxRs and TrxR-like FNRs, as well as variations in their occurrence in different microorganisms, we hypothesized that low Mr TrxR may be able to replace TrxR-like FNR in, for example, the reduction of NrdI. In this study, characterization of TrxR from B. cereus has revealed a weak FNR activity towards NrdI reduction. Additionally, the crystal structure shows that only one out of two binding sites of the B. cereus TrxR homodimer is occupied with NADPH, indicating a possible asymmetric co-substrate binding in TrxR.

• Hammerstad, Marta & Hersleth, Hans-Petter (2021). Overview of structurally homologous flavoprotein oxidoreductases containing the low Mr thioredoxin reductase-like fold – A functionally diverse group. Archives of Biochemistry and Biophysics. ISSN 0003-9861. 702, s. 1–19. doi: 10.1016/j.abb.2021.108826. Fulltekst i vitenarkiv Vis sammendrag

  Structural studies show that enzymes have a limited number of unique folds, although structurally related enzymes have evolved to perform a large variety of functions. In this review, we have focused on enzymes containing the low molecular weight thioredoxin reductase (low Mr TrxR) fold. This fold consists of two domains, both containing a three-layer ββα sandwich Rossmann-like fold, serving as flavin adenine dinucleotide (FAD) and, in most cases, pyridine nucleotide (NAD(P)H) binding-domains. Based on a search of the Protein Data Bank for all published structures containing the low Mr TrxR-like fold, we here present a comprehensive overview of enzymes with this structural architecture. These range from TrxR-like ferredoxin/flavodoxin NAD(P)+ oxidoreductases, through glutathione reductase, to NADH peroxidase. Some enzymes are solely composed of the low Mr TrxR-like fold, while others contain one or two additional domains. In this review, we give a detailed description of selected enzymes containing only the low Mr TrxR-like fold, however, catalyzing a diversity of chemical reactions. Our overview of this structurally similar, yet functionally distinct group of flavoprotein oxidoreductases highlights the fascinating and increasing number of studies describing the diversity among these enzymes, especially during the last decade(s).

• Hammerstad, Marta; Gudim, Ingvild & Hersleth, Hans-Petter (2020). The Crystal Structures of Bacillithiol Disulfide Reductase Bdr (YpdA) Provide Structural and Functional Insight into a New Type of FAD-Containing NADPH-Dependent Oxidoreductase. Biochemistry. ISSN 0006-2960. 59(51), s. 4793–4798. doi: 10.1021/acs.biochem.0c00745. Fulltekst i vitenarkiv Vis sammendrag

  Low G+C Gram-positive Firmicutes, such as the clinically important pathogens Staphylococcus aureus and Bacillus cereus, use the low-molecular weight thiol bacillithiol (BSH) as a defense mechanism to buffer the intracellular redox environment and counteract oxidative stress encountered by human neutrophils during infections. The protein YpdA has recently been shown to function as an essential NADPH-dependent reductase of oxidized bacillithiol disulfide (BSSB) resulting from stress responses and is crucial for maintaining the reduced pool of BSH and cellular redox balance. In this work, we present the first crystallographic structures of YpdAs, namely, those from S. aureus and B. cereus. Our analyses reveal a uniquely organized biological tetramer; however, the structure of the monomeric subunit is highly similar to those of other flavoprotein disulfide reductases. The absence of a redox active cysteine in the vicinity of the FAD isoalloxazine ring implies a new direct disulfide reduction mechanism, which is backed by the presence of a potentially gated channel, serving as a putative binding site for BSSB in the proximity of the FAD cofactor. We also report enzymatic activities for both YpdAs, which along with the structures presented in this work provide important structural and functional insight into a new class of FAD-containing NADPH-dependent oxidoreductases, related to the emerging fight against pathogenic bacteria.

• Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2019). A Research-Inspired Biochemistry Laboratory Module - Combining Expression, Purification, Crystallization, Structure-Solving, and Characterization of a Flavodoxin-like Protein. Biochemistry and Molecular Biology Education. ISSN 1470-8175. 47(3), s. 318–332. doi: 10.1002/bmb.21218. Fulltekst i vitenarkiv Vis sammendrag

  Many laboratory courses consist of short and seemingly unconnected individual laboratory exercises. To increase the course consistency, relevance, and student engagement, we havedevelopedaresearch-inspiredandproject-basedmodule, “From Gene to Structure and Function”. This 2.5-week full-day biochemistry and structural biology module covers protein expression, purification, structure solving, and characterization.Themoduleiscenteredaroundthe flavodoxin-likeprotein NrdI, involved in the activation of the bacterial ribonucleotide reductase enzyme system. Through an in-depth focus on one specific protein, the students will learn the basic laboratory skills needed in order to generate a broader knowledge and breadth within the field. With respect to generic skills, the studentsreporttheir findingsasascientificarticle,withtheaim to learn to present concise research results and write scientific papers. The current research-inspired project has the potential ofbeingfurtherdevelopedintoamorediscovery-drivenproject and extended to include other molecular biological techniques orbiochemical/biophysicalcharacterizations.Instudentevaluations, this research-inspired laboratory course has received very high ratings and been highly appreciated, where the students have gained research experience for more independent future work in the laboratory. © 2019 The Authors. Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry andMolecularBiology,47(3):318–332,2019.

• Olsbu, Inger Kirstine; Zoppellaro, Giorgio; Andersson, Karl Kristoffer; Boucher, Jean-Luc & Hersleth, Hans-Petter (2018). Importance of Val567 on heme environment and substrate recognition of neuronal nitric oxide synthase. FEBS Open Bio. 8(9), s. 1553–1566. doi: 10.1002/2211-5463.12503. Fulltekst i vitenarkiv Vis sammendrag

  Nitric oxide (NO) produced by mammalian nitric oxide synthases (mNOSs) is an important mediator in a variety of physiological functions. Crystal structures of mNOSs have shown strong conservation of the active‐site residue Val567 (numbering for rat neuronal NOS, nNOS). NOS‐like proteins have been identified in several bacterial pathogens, and these display striking sequence identity to the oxygenase domain of mNOS (NOSoxy), with the exception of a Val to Ile mutation at the active site. Preliminary studies have highlighted the importance of this Val residue in NO‐binding, substrate recognition, and oxidation in mNOSs. To further elucidate the role of this valine in substrate and substrate analogue recognition, we generated five Val567 mutants of the oxygenase domain of the neuronal NOS (nNOSoxy) and used UV‐visible and EPR spectroscopy to investigate the effects of these mutations on the heme distal environment, the stability of the heme‐FeII‐CO complexes, and the binding of a series of substrate analogues. Our results are consistent with Val567 playing an important role in preserving the integrity of the active site for substrate binding, stability of heme‐bound gaseous ligands, and potential NO production.

• Gudim, Ingvild; Hammerstad, Marta; Lofstad, Marie & Hersleth, Hans-Petter (2018). Characterization of different flavodoxin reductase-flavodoxin (FNR-Fld) interactions reveals an efficient FNR-Fld redox pair and identifies a novel FNR subclass. Biochemistry. ISSN 0006-2960. 57(37), s. 5427–5436. doi: 10.1021/acs.biochem.8b00674. Fulltekst i vitenarkiv Vis sammendrag

  Flavodoxins (Flds) are small, bacterial proteins that transfer electrons to various redox enzymes. Flavodoxins are reduced by ferredoxin/flavodoxin NADP+ oxidoreductases (FNRs), but little is known of the FNR-Fld interaction. Here, we compare the interactions of two flavodoxins (Fld1–2), one flavodoxin-like protein (NrdI), and three different thioredoxin reductase (TrxR)-like FNRs (FNR1–3), all from Bacillus cereus. Steady-state kinetics shows that the FNR2-Fld2 electron transfer pair is particularly efficient, and redox potential measurements also indicate that this is the most favorable electron donor/acceptor pair. Furthermore, crystal structures of FNR1 and FNR2 show that the proteins have crystallized in different conformations, a closed and an open conformation, respectively. We suggest that a large-scale conformational rearrangement takes place during the FNR catalytic cycle to allow for the binding and reduction of the Fld and, subsequently, the re-reduction of the FNR by NADPH. Finally, inspection of the residues surrounding the FAD cofactor in the FNR active site shows that a key isoalloxazine ring-stacking residue is different in FNR1 and FNR2, which could explain the large difference in catalytic efficiency between the two FNRs. To date, all of the characterized TrxR-like FNRs have a residue with aromatic character stacking against the FAD isoalloxazine ring, and this has been thought to be a conserved feature of this class of FNRs. FNR1, however, has a valine in this position. Bioinformatic analysis shows that the TrxR-like FNRs can actually be divided into two groups, one group where the FAD-stacking residue has aromatic character and another group where it is valine.

• Gudim, Ingvild; Lofstad, Marie; Beek, Wouter Van & Hersleth, Hans-Petter (2018). High-resolution crystal structures reveal a mixture of conformers of the Gly61-Asp62 peptide bond in an oxidized flavodoxin from Bacillus cereus. Protein Science. ISSN 0961-8368. 27(8), s. 1439–1449. doi: 10.1002/pro.3436. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta & Hersleth, Hans-Petter (2017). Measurement of FNR-NrdI Interaction by Microscale Thermophoresis (MST). Bio-protocol. 7(8), s. e2223–e2223. doi: 10.21769/BioProtoc.2223. Fulltekst i vitenarkiv Vis sammendrag

  This protocol describes how to measure protein-protein interactions by microscale thermophoresis (MST) using the MonolithTM NT.115 instrument (NanoTemper). We have used the protocol to determine the binding affinities between three different flavodoxin reductases (FNRs) and a flavodoxin-like protein, NrdI, from Bacillus cereus (Lofstad et al., 2016). NrdI is essential in the activation of the manganese-bound form of the class Ib ribonucleotide reductase (RNR) system. RNRs, in turn, are the only source of the de novo synthesis of deoxyribonucleotides required for DNA replication and repair in all living organisms.

• Lofstad, Marie; Gudim, Ingvild; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2016). Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus. Biochemistry. ISSN 0006-2960. 55(36), s. 4998–5001. doi: 10.1021/acs.biochem.6b00699. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Hammerstad, Marta; Gudim, Ingvild; Andersen, Hilde Kristin; Aracena-Solem, Matias & Hersleth, Hans-Petter (2026). Metals and thiols in bacterial defense and survival. Fulltekst i vitenarkiv
• Hammerstad, Marta & Hersleth, Hans-Petter (2025). Structural studies of flavodoxins from Bacillus cereus in different redox states. Fulltekst i vitenarkiv
• Hammerstad, Marta; Karlsen, Marthe Lindahl; Gudim, Ingvild; Gutiérrez-Fernández, Javier & Hersleth, Hans-Petter (2025). Structural and functional studies of enzymes involved in thiol-based redox pathways. Fulltekst i vitenarkiv
• Karlsen, Marthe Lindahl; Hersleth, Hans-Petter & Hammerstad, Marta (2025). Structural and functional insights into bacillithiol disulfide reductase – A potential antimicrobial target. Fulltekst i vitenarkiv
• Hammerstad, Marta; Karlsen, Marthe Lindahl; Gutiérrez-Fernández, Javier; Gudim, Ingvild & Hersleth, Hans-Petter (2024). Structures of bacilli­thiol and myco­thiol di­sulfide reductases of bacilli and mycobacteria. Acta Crystallographica Section A: Foundations of Crystallography. ISSN 0108-7673. 80. doi: 10.1107/S2053273324099200. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2024). Structures of bacillithiol and mycothiol disulfide reductases of bacilli and mycobacteria. Fulltekst i vitenarkiv
• Hammerstad, Marta; Karlsen, Marthe Lindahl; Fernandez, Javier Gutierrez; Gudim, Ingvild & Hersleth, Hans-Petter (2024). Structures of bacillithiol and mycothiol disulfide reductases of Firmicutes and Actinobacteria. Fulltekst i vitenarkiv
• Karlsen, Marthe Lindahl; Hersleth, Hans-Petter & Hammerstad, Marta (2024). Structural and functional investigation of bacillithiol disulfide reductases. Fulltekst i vitenarkiv
• Hammerstad, Marta; Andersen, Hilde Kristin; Rugtveit, Anne Kristine; Dahlen, Sondov Åsmundson Braathen & Hersleth, Hans-Petter (2023). Functional diversity among flavin-containing oxidoreductases involved in redox protection, iron homeostasis, and ribonucleotide reduction. Fulltekst i vitenarkiv
• Fernandez, Javier Gutierrez; Hammerstad, Marta & Hersleth, Hans-Petter (2023). Structural determination of Mycobacterium smegmatis and Rhodococcus erythropolis mycothiol disulphide reductases. Fulltekst i vitenarkiv
• Karlsen, Marthe Lindahl; Hersleth, Hans-Petter & Hammerstad, Marta (2023). Diversity among bacillithiol disulfide reductases – a structural and functional investigation. Fulltekst i vitenarkiv
• Fernandez, Javier Gutierrez; Hammerstad, Marta & Hersleth, Hans-Petter (2023). Structural determination of Mycobacterium smegmatis and Rhodococcus erythropolis mycothiol disulphide reductases. Fulltekst i vitenarkiv
• Fernandez, Javier Gutierrez; Hammerstad, Marta & Hersleth, Hans-Petter (2023). Structural determination of Mycobacterium smegmatis and Rhodococcus erythropolis mycothiol disulphide reductases. Fulltekst i vitenarkiv
• Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2023). A Research-inspired Laboratory Module on a Redox Protein Combining Biochemistry and Structural Biology. Fulltekst i vitenarkiv
• Fernandez, Javier Gutierrez; Hammerstad, Marta & Hersleth, Hans-Petter (2022). Structural determination of Mycobacterium tuberculosis and Rhodococcus erythropolis mycothiol disulphide reductases. Fulltekst i vitenarkiv
• Hammerstad, Marta; Gudim, Ingvild & Hersleth, Hans-Petter (2022). Redox protection of pathogens by low molecular weight thiols. Fulltekst i vitenarkiv
• Rese, Morten; Hammerstad, Marta & Hersleth, Hans-Petter (2022). Diversity in myoglobin function. Fulltekst i vitenarkiv
• Andersen, Hilde Kristin; Hersleth, Hans-Petter & Hammerstad, Marta (2022). Structure-function studies of ferredoxin-flavodoxin NADP+ oxidoreductase 1 from Bacillus cereus as an iron-uptake oxidoreductase. Fulltekst i vitenarkiv
• Rese, Morten; Hammerstad, Marta & Hersleth, Hans-Petter (2022). Diversity in myoglobin function. Fulltekst i vitenarkiv
• Hammerstad, Marta; Gudim, Ingvild & Hersleth, Hans-Petter (2022). Redox protection of pathogens by low molecular weight thiols. Fulltekst i vitenarkiv
• Hammerstad, Marta; Gudim, Ingvild & Hersleth, Hans-Petter (2020). The Crystal Structures of Bacillithiol Disulfide Reductase YpdA Reveal Structural and Functional Insight into a New Type of FAD-Containing NADPH-Dependent Oxidoreductases. Fulltekst i vitenarkiv
• Hammerstad, Marta; Gudim, Ingvild; Lofstad, Marie; Røhr, Åsmund Kjendseth & Hersleth, Hans-Petter (2019). Enzyme Activation by a Flavoprotein Redox Network. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Beek, Wouter van & Hersleth, Hans-Petter (2019). New structural insight into the well known peptide flip observed in flavodoxins. Acta Crystallographica Section A: Foundations and Advances. A75, s. e123–e123. doi: 10.1107/S2053273319094336. Fulltekst i vitenarkiv
• Hammerstad, Marta; Gudim, Ingvild; Lofstad, Marie; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2019). Enzyme activation by a flavoprotein redox network. Acta Crystallographica Section A: Foundations and Advances. A75, s. e128–e128. doi: 10.1107/S2053273319094282. Fulltekst i vitenarkiv
• Kendall-Price, Sophie; Evans, Rhiannon M; Rowbotham, Jack S; Reeve, Holly A; Carr, Stephen B & Frogley, Mark D [Vis alle 11 forfattere av denne artikkelen] (2019). Generating Single Metalloprotein Crystals in Well-Defined Redox States – Electrochemical Microspectroscopy As a Tool for Mechanistic Studies. Meeting Abstracts - The Electrochemical Society [ECS]. ISSN 1091-8213. 9, s. 425–425. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Røhr, Åsmund Kjendseth & Hersleth, Hans-Petter (2019). Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Beek, Wouter van & Hersleth, Hans-Petter (2019). New structural insight into the well known peptide flip observed in flavodoxins. Fulltekst i vitenarkiv
• Hammerstad, Marta; Zaltariov, Mirela F.; Arabshahi, Homayon John; Jovanovic, Katarina; Richter, Klaus W. & Cazacu, Maria [Vis alle 14 forfattere av denne artikkelen] (2019). New thiosemicarbazone derivatives and their copper(II) complexes as potential inhibitors against mammalian ribonucleotide reductase. Fulltekst i vitenarkiv
• Andersen, Niels Højmark; Hammerstad, Marta; Zaltariov, Mirela F.; Rapta, Peter; Arion, Vladimir B. & Hersleth, Hans-Petter (2019). Interaction of Thiosemicarbazones with the Ribonucleotide Reductase R2 subunit Studied by Resonance Raman Spectroscopy. Fulltekst i vitenarkiv
• Hammerstad, Marta; Gudim, Ingvild; Lofstad, Marie; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2019). Characterization of Proteins in the Ribonucleotide Reductase RedoxNetwork. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Røhr, Åsmund Kjendseth & Hersleth, Hans-Petter (2018). Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Andersen, Niels Højmark; Hammerstad, Marta; Zaltariov, Mirela F.; Arion, Vladimir B. & Hersleth, Hans-Petter (2018). Interaction of Thiosemicarbazones with Ribonucleotide Reductase studied by Resonance Raman Spectroscopy. Fulltekst i vitenarkiv
• Chaudhari, Sujata; Olsbu, Inger Kirstine; Alqarzaee, Abdulelah; Singh, Ryan; Schulze, Thomas & Zimmerman, Matthew [Vis alle 8 forfattere av denne artikkelen] (2018). Endogenous nitric oxide synthase (NOS) activity reduces staphylococcal lifespan during stationary phase. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta & Hersleth, Hans-Petter (2018). Enzyme activation by a flavoprotein redox network. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta & Hersleth, Hans-Petter (2018). Enzyme activation by a flavoprotein redox network. NBS-nytt. ISSN 0801-3535. s. 40–40. Fulltekst i vitenarkiv
• Olsbu, Inger Kirstine; Chaudhari, Sujata; Thomas, Vinai Chittezham & Hersleth, Hans-Petter (2018). Potential reductase partner for Staphylococcus aureus Nitric Oxide Synthase. Fulltekst i vitenarkiv
• Olsbu, Inger Kirstine; Chaudhari, Sujata; Thomas, Vinai Chittezham & Hersleth, Hans-Petter (2018). Potential reductase partner for Staphylococcus aureus Nitric Oxide Synthase. NBS-nytt. ISSN 0801-3535. s. 40–40. Fulltekst i vitenarkiv
• Johannesen, Hedda; Cumar, Rohit; Hammerstad, Marta; Hersleth, Hans-Petter; Logan, Derek & Andersson, Karl Kristoffer (2017). Investigation of NrdD and NrdG from the two Firmicutes Bacillus cereus Lactococcus lactis. Fulltekst i vitenarkiv
• Johannesen, Hedda; Kumar, Rohit; Hersleth, Hans-Petter; Hammerstad, Marta; Logan, Derek & Andersson, Karl Kristoffer (2017). A STRUCTURAL AND FUNCTIONAL INVESTIGATION OF RIBONUCLEOTIDE REDUCTASE CLASS III IN BACILLUS CEREUS. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta & Hersleth, Hans-Petter (2017). Enzyme activation by a flavoprotein redox network. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the class Ib ribonucleotide reductase by a flavodoxin reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Johannesen, Hedda; Hersleth, Hans-Petter; Hammerstad, Marta & Andersson, K. Kristoffer (2017). A structural and functional investigation of ribonucleotide reductase class III in Bacillus cereus. Fulltekst i vitenarkiv
• Shoor, Marita; Gudim, Ingvild; Hammerstad, Marta & Hersleth, Hans-Petter (2017). Structural and functional characterization of redox proteins in an enzyme activating network involving the thioredoxin reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Olsbu, Inger Kirstine; Lombard, M; Hersleth, Hans-Petter; Boucher, Jean-Luc & Andersson, K. Kristoffer (2017). Key role of Val-567 on L-Arg analogues and heme ligands to neuronal nitric oxide syntase. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the Class Ib Ribonucleotide Reductase by a Flavin Network in Bacillus cereus. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the class Ib ribonucleotide reductase by a flavodoxin reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the class Ib RNR by a flavodoxin reductase in B. cereus. NSB-nytt. s. 105–105. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the Class Ib Ribonucleotide Reductase by a Flavin Network in Bacillus cereus. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the class IB ribonucleotide reductase by a flavodoxin reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2017). Activation of the Class Ib Ribonucleotide Reductase by a Flavin Network in Bacillus cereus. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2017). Combining Protein X-ray Crystallography and in situ Single- Crystal UV-Vis and Raman Spectroscopy to Grasp the True Structure of Haem- and Flavoproteins. Fulltekst i vitenarkiv
• Johannesen, Hedda; Hammerstad, Marta; Hersleth, Hans-Petter & Andersson, K. Kristoffer (2017). A structural and functional investigation of ribonucleotide reductase class III. Fulltekst i vitenarkiv
• Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). A research-inspired biochemistry laboratory module – Combining, expression,purification, crystallisation, structure solving and characterisation of a flavdoxin-like protein. NBS-nytt. ISSN 0801-3535. s. 63–63. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2017). A research-inspired biochemistry laboratory module – Combining, expression,purification, crystallisation, structure solving and characterisation of a flavdoxin-like protein. Fulltekst i vitenarkiv
• Lofstad, Marie; Gudim, Ingvild; Kjendseth, Åsmund Røhr; Andersen, Niels Højmark; Beek, Wouter van & Andersson, K. Kristoffer [Vis alle 7 forfattere av denne artikkelen] (2017). Combining Protein X-ray crystallography and in situ single-crystal UV-Vis and Raman spectroscopy to grasph the true structure of haem- and flavoproteins. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2017). Activation of the class Ib ribonucleotide reductase by a flavodoxin reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Hammerstad, Marta; Lofstad, Marie; Böttger, Lars H.; Kjendseth, Åsmund Røhr; Hersleth, Hans-Petter & Zaltariov, Mirela-Fernanda [Vis alle 9 forfattere av denne artikkelen] (2017). INHIBITION OF CLASS 1A RIBONUCLEOTIDE REDUCTASE, AND A COMPARISON OF THE DIMANGANESE ACTIVE SITES OF CLASS IB RIBONUCLEOTIDE REDUCTASE AND MANGANESE CATALASE. Fulltekst i vitenarkiv Vis sammendrag

  INHIBITION OF CLASS 1A RIBONUCLEOTIDE REDUCTASE, AND A COMPARISON OF THE DIMANGANESE ACTIVE SITES OF CLASS IB RIBONUCLEOTIDE REDUCTASE AND MANGANESE CATALASE Marta Hammerstad1*; Marie Lofstad1*; Lars H. Böttger2*; Åsmund Kjendseth Røhr3; Hans-Petter Hersleth1; Mirela F. Zaltariov4; Vladimir B. Arion4; Edward I. Solomon2 and K. Kristoffer Andersson1 1Department of Biosciences, University of Oslo, Pb.1066 Blindern, NO-0316 Oslo, Norway 2Department of Chemistry, Stanford University, Stanford, CA 94305, USA 3Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432 Ås, Norway 4Institute of Inorganic Chemistry, Universität Wien, AT-1090 Vienna, Austria *These three authors contributed equally Presenting Author’s e-mail address: k.k.andersson@ibv.uio.no Ribonucleotide reductases (RNRs) are enzymes that convert RNA building blocks into DNA building blocks [1]. The reductive reaction by RNRs requires a cysteine thiyl radical, which, in the case of class Ia or Ib RNRs, is initiated by an FeIII2- or MnIII2-tyrosyl radical (Y•) cofactor in the R2 subunit of RNR. During enzymatic turnover, the cofactor is activated by oxygen, and generates a Y• that is transported from the smaller R2 subunit to the large catalytic subunit R1 of RNR, where DNA building blocks are formed. The small subunit of class Ia RNRs can be inhibited by several small compounds [2], through the inhibition of the active FeIII2- Y• cofactor. We have performed interaction studies and Kd measurements of a mammalian R2 protein with several newly synthesized compounds, and studied their potential inhibitory effect on the protein with EPR, showing promising results. Manganese catalase (MnCAT) enzymes [3] contain an active site that is similar in structure to the MnIII2 form of NrdF (the R2 subunit in class Ib RNR), characterized by a carboxylate-bridged MnIII-O-MnIII cofactor. However, it catalyzes a different reaction – the degradation of hydrogen peroxide to dioxygen and water. A still unresolved question is how these enzymes containing similar active sites can catalyze different reactions. A variety of spectroscopic methods have been used to try to resolve this question. Samples containing NrdF with active MnIII-O-MnIII cofactor have been prepared and studied by circular dichroism (CD) and magnetic CD (MCD) spectroscopy. The data show both similar and distinct features as compared to MnCAT. 1. A.B. Tomter; G. Zoppelaro; N.H. Andersen; H.-P. Hersleth; M. Hammerstad; Å.K. Røhr; G.K. Sandvik; G.E. Nilsson; C.B. Bell; A.L. Barra; E. Blasco; L. Le Pape; E.I. Solomon; and K.K. Andersson. Coord. Chem. Rev. (2013), 257, 3 2. A. Popovic-Bijelic A; C.R. Kowol; M.E.S. Lind; J. Luo; F. Himo; A.E. Enyedy; V.B. Arion; and A. Gräslund. (2011) J. Inorg. Biochem. 105, 1422-1431 3. T.C. Brunold; D.R. Gamelin; T.L. Stemmler; S.K. Mandal; W.H. Armstrong; J.E. Penner-Hahn; and E. I. Solomon. J. Am. Chem. Soc. (1998), 120, 8724

• Lofstad, Marie; Böttger, Lars H.; Røhr, Åsmund Kjendseth; Hersleth, Hans-Petter; Hammerstad, Marta & Solomon, Edward I. [Vis alle 7 forfattere av denne artikkelen] (2016). A comparison of the dimanganese active sites of class Ib ribonucleotide reductase and manganese catalase by CD and MCD spectroscopy. NBS-nytt. ISSN 0801-3535. s. 45–45. Fulltekst i vitenarkiv
• Hammerstad, Marta; Hersleth, Hans-Petter; Lofstad, Marie; Johannesen, Hedda; Tomter, Ane Berg & Røhr, Åsmund Kjendseth [Vis alle 7 forfattere av denne artikkelen] (2016). Structural Insight into the Function of Ribonucleotide Reductase. Fulltekst i vitenarkiv
• Johannesen, Hedda; Hersleth, Hans-Petter; Hammerstad, Marta & Andersson, K. Kristoffer (2016). A Structural and Functional Investigation of Ribonucleotide Reductase Class III In Bacillus Cereus. Fulltekst i vitenarkiv
• Lofstad, Marie; Gudim, Ingvild; Kjendseth, Åsmund Røhr; Hammerstad, Marta; Andersson, K. Kristoffer & Hersleth, Hans-Petter (2016). Activation of Class Ib Ribonucleotide Reductase by NRDI and Its Reductase Partner in Bacillus cereus. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2016). Probing enzyme activation networks - structural and functional studies of flavoproteins in Bacillus cereus. Fulltekst i vitenarkiv
• Olsbu, Inger Kirstine; Murielle, Lombard; Hersleth, Hans-Petter; Jean-Luc, Boucher & Andersson, K. Kristoffer (2016). Key Role of VAL567 on L-Argenine Analogues and HEME Ligands Binding to Neuronal Nitric Oxide Synthase. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter; Gudim, Ingvild; Lofstad, Marie; Kjendseth, Åsmund Røhr; beek, Wouter Van & Giullaume, Pompidor [Vis alle 11 forfattere av denne artikkelen] (2016). Grasping the True Structure of Haem- and Flavoproteins – Combining X-RAY Crystallography and In Situ Single-Crystal UV-VIS and Raman Spectroscopy. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2016). Probing enzyme activation networks - structural and functional studies of flavoproteins in Bacillus cereus. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter (2016). Probing enzyme activation networks ‐ structural and functional studies of flavoproteins in Bacillus cereus. Fulltekst i vitenarkiv
• Lofstad, Marie; Gudim, Ingvild; beek, Wouter Van; Pompidor, Guillaume; Kjendseth, Åsmund Røhr & Andersson, K. Kristoffer [Vis alle 7 forfattere av denne artikkelen] (2016). Radiation damage of haem- and flavoproteins –combining X-ray crystallography and single-crystal UV-Vis and Raman spectroscopy. 9th International Workshop on X-ray Radiation Damage to Biological Crystalline Samples. Fulltekst i vitenarkiv
• Lofstad, Marie; Gudim, Ingvild; beek, Wouter Van; Pompidor, Guillaume; Kjendseth, Åsmund Røhr & Andersson, K. Kristoffer [Vis alle 7 forfattere av denne artikkelen] (2016). Radiation damage of haem- and flavoproteins – combining X-ray crystallography and single-crystal UV-Vis and Raman spectroscopy. Fulltekst i vitenarkiv
• Lofstad, Marie; Böttger, Lars H.; Kjendseth, Åsmund Røhr; Hersleth, Hans-Petter; Hammerstad, Marta & Solomon, Edward I. [Vis alle 7 forfattere av denne artikkelen] (2016). A COMPARISON OF THE DIMANGANESE ACTIVE SITES OF CLASS IB RIBONUCLEOTIDE REDUCTASE AND MANGANESE CATALASE BY CD AND MCD SPECTROSCOPY. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Hammerstad, Marta; Kjendseth, Åsmund Røhr & Hersleth, Hans-Petter (2016). Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus. Fulltekst i vitenarkiv
• Johannesen, Hedda; Hersleth, Hans-Petter; Logan, Derek; Hammerstad, Marta & Andersson, K. Kristoffer (2016). A structural and functional investigation of Ribonucleotide reductase Class III in Bacillus cereus- Investigating the interaction and mechanism of the NrdD and NrdG complex. Fulltekst i vitenarkiv
• Johannesen, Hedda; Hersleth, Hans-Petter; Logan, Derek; Hammerstad, Marta & Andersson, K. Kristoffer (2016). A structural and functional investigation of Ribonucleotide reductase Class III in Bacillus cereus- Investigating the interaction and mechanism of the NrdD and NrdG complex. Fulltekst i vitenarkiv
• Johannesen, Hedda; Hersleth, Hans-Petter; Hammerstad, Marta & Andersson, K. Kristoffer (2016). A structural and functional investigation of Ribonucleotide reductase Class III in Bacillus cereus. NBS-nytt. ISSN 0801-3535. s. 65–65. Fulltekst i vitenarkiv
• Hammerstad, Marta; Hersleth, Hans-Petter; Tomter, Ane Berg; Røhr, Åsmund Kjendseth & Andersson, K. Kristoffer (2016). Structural Insight into the Function of Ribonucleotide Reductase. NBS-nytt. ISSN 0801-3535. s. 64–64. Fulltekst i vitenarkiv
• Gudim, Ingvild; Lofstad, Marie; Andersson, K. Kristoffer; Hammerstad, Marta & Hersleth, Hans-Petter (2016). Probing enzyme activation networks ‐ structural and functional studies of flavoproteins in Bacillus cereus. NBS-nytt. ISSN 0801-3535. s. 45–45. Fulltekst i vitenarkiv
• Hersleth, Hans-Petter & Røhr, Åsmund Kjendseth (2015). Teaching a general molecular bioscience master course as a project ”From gene to structure”. Fulltekst i vitenarkiv
• Gudim, Ingvild & Hersleth, Hans-Petter (2015). Structure of a ferredoxin/flavodoxin-NADP(H) oxidoreductase in Bacillus cereus. Fulltekst i vitenarkiv
• Andersen, Hilde Kristin; Hammerstad, Marta & Hersleth, Hans-Petter (2022). Struktur-funksjonsstudier av ferredoksin-flavodoksin NADP+ oksidoreduktase 1 fra Bacillus cereus som en jern-opptak oksidoreduktase. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Bacillus cereus har tre enzymer som er annotert som ferredoksin-flavodoksin NADP+ oksidoreduktaser (FNRer). FNR3 er vist å redusere disulfidformen av bacillitiol, FNR2 er vist å effektivt redusere flavodoksiner, men det er enda ikke funnet noen god redokspartner til FNR1. FNR1 er vist å skille seg fra FNR2 ved å være del av en fylogenetisk undergruppe av tioredoksinreduktase-aktige FNRer hvor en konservert aromatisk residu i C-terminalen, som stabiliserer FAD-kofaktoren er erstattet med valin sammenlignet med FNR2-gruppen. Staphylococcus aureus har en nær homolog til FNR1 som deler den konserverte valinresiduen, som har blitt vist å kunne fungere som en jern-opptak-oksidoreduktase (IruO). IruO kan tilgjengeliggjøre jern for bakterier ved å redusere hemoksygenasene iron-regulated surface determinant (Isd)G og IsdI som degraderer hem, eller sideroforer. B. cereus har kun en homolog til IsdG, men ikke IsdI. I dette prosjektet har det blitt utført aktivitetsstudier for å undersøke om B. cereus FNR1 kan fungere som en IruO, og redusere IsdG for å degradere hem, ved bruk av UV-vis-spektroskopi. FNR1 og IsdG har blitt uttrykt og renset. Strukturen til IsdG er blitt løst ved bruk av proteinkrystallografi. IsdG viste å ha svært lik struktur i B. cereus og S. aureus, med ferredoksinfolding og de konserverte residuene Asn7, Trp67 og His77 i bindingssetet til hem. Aktivitetsstudiene viste at FNR1 kunne redusere IsdG for å degradere hem og tilgjengeliggjøre jern. FNR1 er anslått å ha evner i samme størrelsesorden til å redusere IsdG som til å redusere flavodoksiner. Aktivitetsstudiene tyder på at hem blir degradert ved først å redusere Fe(III) til Fe(II) og at det går via Fe(II)-O2 som i kanoniske hemoksygenaser.

• Rese, Morten; Hersleth, Hans-Petter; Hammerstad, Marta & Andersen, Niels Højmark (2022). Functional diversity of myoglobin isozymes from Carassius auratus - Biophysical study of myoglobin as a peroxidase. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Myoglobin (Mb) is a heme protein expressed in oxidative muscle tissue and functions in oxygen storage and transport. Mb can also display complex redox chemistry involved in several important physiological processes including scavenging of reactive oxygen species and nitric oxide metabolism. Goldfish and the common carp are the only vertebrates known today that express two paralogs of Mb (Mb1 and Mb2) as a result of a recent whole genome duplication. Mb1 is expressed in gills, liver, and skeletal muscle tissue, whereas Mb2 is exclusively expressed in the brain. The tissue-specific expression led to work showing that Mb2 in carp fish is a more effective peroxidase. In this study, work has been done to gain detailed structural and functional insight into the differences of the goldfish Mb1 and Mb2 isozymes by biophysical characterization and 3D structure analysis. The intensively studied Mb from horse heart (hMb) has been studied together with Mb1 and Mb2 as a reference. The reaction of Mb with hydrogen peroxide (H2O2) has been of particular interest. In addition, studies on how radiation damage during diffraction data collection affects redox states of Mb have been performed. This study shows that goldfish Mb2 reacts with H2O2 significantly faster than Mb1. Structural modeling of Mb1 and Mb2 indicates that no differences around the active site are responsible for the difference in reactivity. The structural basis of this functional difference is therefore complex in nature and might be explained by altered dynamics as a consequence of differing amino acid composition towards the surface of the proteins. The ferric and ferryl redox states of Mb are damaged by X-ray radiation during diffraction data collection. The ferric state is significantly more susceptible to radiation damage compared to the ferryl state. This study shows the importance of performing a time/dose calculation on the amount of radiation a specific redox state can handle when collecting diffraction data.

• Hersleth, Hans-Petter; Hammerstad, Marta & Dahlen, Sondov Åsmundson Braathen (2021). Structure and function of FNR1 from Bacillus cereus undergoing a mutation. Universitetet i Oslo. Fulltekst i vitenarkiv
• Rugtveit, Anne Kristine; Hammerstad, Marta & Hersleth, Hans-Petter (2021). Structural and functional studies of a ferredoxin/flavodoxin NADP+-oxidoreductase mutant from Bacillus cereus. Universitetet i Oslo. Fulltekst i vitenarkiv
• Gudim, Ingvild; Hersleth, Hans-Petter; Hammerstad, Marta & Sørlie, Morten (2018). Characterisation of flavodoxin and ferredoxin/flavodoxin reductases from Bacillus cereus and their interactions. Reprosentralen, University of Oslo. Fulltekst i vitenarkiv
• Olsbu, Inger Kirstine; Hersleth, Hans-Petter & Sørlie, Morten (2018). Substrate recognition and redox partner identification in nitric oxide synthases. Reprosentralen, University of Oslo. Fulltekst i vitenarkiv
• Shoor, Marita; Hersleth, Hans-Petter; Gudim, Ingvild & Hammerstad, Marta (2017). Structural and functional characterization of the redox protein Thioredoxin reductase from Bacillus cereus. Universitetet i Oslo. Fulltekst i vitenarkiv
• Lofstad, Marie; Andersson, K. Kristoffer; Hersleth, Hans-Petter; Hammerstad, Marta & Kjendseth, Åsmund Røhr (2017). Activation Pathways of the Class Ib Ribonucleotide Reductase in Bacillus cereus. Universitet i Oslo. Fulltekst i vitenarkiv
• Wu, Bernt; Hersleth, Hans-Petter; Hammerstad, Marta & Andersson, K. Kristoffer (2015). Purification and characterization of Flavohemoglobin - A flavoheme enzyme. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Flavohemoglobin is a flavoheme enzyme that catalyzes dioxygenation of nitric oxide (NO) to nitrate NO3–. NO is diatomic radical gas produced by enzymatic and non-enzymatic oxidation of reduced nitrogenous compounds. NO acts as a membrane-permeable signal molecule in mammals, in addition to being a toxin at higher concentrations and being utilized by the immune system against invading pathogens. FHb is involved in protection against the cytotoxic effects of NO (termed nitrosative stress) and is found in a range of bacterial species and some fungi. FHbs are not found in higher eukaryotes, but is employed by a range of pathogens, and is a potential therapeutic target. In this thesis we sought to investigate the FHb from Bacillus cereus by determination of the X-ray crystal structure as only a few structures of FHb from different organisms have been obtained. The protein was successfully cloned and expressed and a purification protocol has been developed, with ammonium sulfate precipitation, anion exchange chromatography and gel filtration. A high yield with high purity was obtained, but with heme and FAD at substoichiometric levels. Crystallization screening resulted in some small needles grown from precipitate, although they were non-reproducible and no crystal structure was obtained. A heme assay was performed in order to identify the heme/protein ratio and protein assays was performed to calculate protein concentration. Testing of reconstitution with heme and FAD was performed with promising results.

• Monka, Susanne; Andersson, K. Kristoffer; Hersleth, Hans-Petter & Hammerstad, Marta (2015). Structural and functional characterisation of ferredoxins in Bacillus cereus. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag

  Ferredoxins are iron-sulfur proteins that transfer electrons in different cellular processes. In Bacillus cereus there are two genes for ferredoxins that have been identified, one present with a [2Fe-2S] cluster (BC2795) and one with a [4Fe- 4S] cluster (BC1483). These proteins can potentially receive electrons from three possible ferredoxin-NADP+-reductases, and further activate different enzymes. In this project, the starting point was to purify and structurally characterize the two ferredoxins in B. cereus and potentially their interactions with redox partners. For the [4Fe-4S] ferredoxin several attempts to overexpress this protein was unsuccessful. However, the [2Fe-2S] ferredoxin (106 amino acids, 11.4 kDa) was successfully overexpressed in Escherichia coli. This [2Fe-2S] ferredoxin was purified in a series of purification steps involving ammonium sulphate, desalting column, Q Sepharose or DEAE columns, and Superdex 75 column. The purification procedure showed to be troublesome because of possible low iron-sulfur cluster content, and because of low UV-vis detection due to the absence of tryptophanes and tyrosines in the protein. Due to the high content of apoprotein, it was also tried to establish a reconstitution procedure for BC2795. The apoform of the protein was crystallized. Nevertheless, it was not possible to solve the structure.

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