Structural Redox Enzymology - Hersleth

The Structural Redox Enzymology (ROX) group uses a combination of biophysical and biochemical methods to understand the structure and function of redox enzyme systems by using protein crystallography, enzyme kinetics, binding studies and different types of spectroscopies.

Picture of the group

Group members Hilde Kristin, Morten, Marta, Javier and Hans-Petter (Photo: Hersleth, UiO)

Picture of Marta and Hans-Petter
Marta & Hans-Petter (Photo: Hersleth)

The group is run by Hans-Petter Hersleth and Marta Hammerstad.

We are also a UiO Structural Biology Core Facilities node, so if you have questions or need help with structural biology you can contact us.        

Picture of some structures solved by the group: NrdI, flavodoxin, thioredoxin reductasem catalase-peroxidase, flavodoxin:ferredoxin reductase, flavodoxin reductase, myoglobin, thioredoxin, NrdI-NrdF complex, bacillithiol disulfide reductase, nitric oxide synthase, ribonucleotide reductase NrdF and cytochrome c552
Examples of proteins we work with (Illustration: Hersleth, UiO)

Research interest:

We have a general interest in the structure and function of proteins, especially redox enzymes using different cofactors to perform their functions. These include haem and other metalloproteins, flavin proteins and thiol-based proteins.

Picture shows cofactors
Redox cofactors (Illustration: Hersleth, UiO)

Redox enzymes are often part of redox networks, where other cofactor-based proteins activate these enzymes. A research focus is to decipher the enzyme mechanisms and activation networks in key redox enzyme systems: 

  • Low molecular weight (LMW) thiols are important biological antioxidants. Many Firmicutes use the LMW thiol bacillithiol as a defense mechanism to buffer the intracellular redox environment and counteract oxidative stress encountered by human neutrophils during infections. One way of protection is through bacillithiolation of the redox active cysteins. This involves a network of several redox enzymes.

  • Show structure of Bdr
    Structure of the protein that reduces oxidised bacillithiol after antioxidant defence by bacillithiol (Illustration: Hersleth, UiO)
  • Ribonucleotide reductase (RNR) converts the RNA building blocks to DNA building blocks, and is one enzyme system we are focusing on. The activation of this system is different in humans and bacteria, as well as within the bacterial classes. These systems involve both di-iron, di-manganese, iron-sulfur, flavin and thiol-based proteins.

  • Show reaction scheme of RNR
    Reaction scheme of bacterial ribonucleotide reductase (Illustration: Hersleth, UiO)
  • Another focus is on a more recently discovered group of thioredoxin reductase-like FAD-containing NADPH-dependent oxidoreductases in Firmicutes. Here, the individual enzymes has evolved to perform different redox reactions, where much of the detailed understanding is lacking.

  • A focus on haem proteins is on the high-valent reaction intermediates generated in several redox cycles of haem proteins. 

  • The X-rays used in protein crystallography can lead to radiation induced damage and reduction of the cofactor redox states in the protein crystals. To understand and cope with these effects, we are combining protein crystallography with in situ single crystal spectroscopic methods at synchrotrons. We have now a new project where we will combine this with neutron protein crystallography.

To decipher the functions of these redox proteins on a molecular and electronic level a combination of biochemical and biophysical methods are needed. We therefore combine protein crystallography (X-ray and neutron), different spectroscopic techniques both in solution and crystals (e.g. UV-vis, Raman), binding studies, kinetic studies, potentiometric studies and activity studies. 

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Funding

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Tags: Biochemistry, structural biology, protein structure, enzymology, redox biology, protein crystallography, spectroscopy, synchrotron
Published July 2, 2017 9:18 PM - Last modified Aug. 10, 2022 2:14 PM