Maria del Carmen Herrera Gonzalez-Molina

• Malecki, Jedrzej Mieczyslaw; Weirich, Sara; Ramirez, Manuel; Hagen, Lars; Al-Egly, Jakin Saad & Anonsen, Jan Haug [Show all 12 contributors for this article] (2025). Identification of substrates and sequence requirements for CARNMT1-mediated histidine methylation of C3H zinc fingers. Journal of Biological Chemistry. ISSN 0021-9258. 301(7). doi: 10.1016/j.jbc.2025.110335. Full text in Research Archive Show summary

  It has recently become clear that protein histidine methylation is widespread and functionally important in many cellular processes, and human CARNMT1 was recently reported as a novel protein histidine methyltransferase (HMT). We describe our independent uncovering of CARNMT1's protein HMT activity and a comprehensive assessment of its methylation targets and substrate specificity. Using a combination of in vitro methylation of cellular extracts and protein mass spectrometry, we identified several CARNMT1 substrates that were fully methylated in cells, all of which were C3H zinc finger (ZnF) proteins. These include the previously identified U2AF1, ZC3H15, and ZC3H18 but also the unreported RBM22, PPP1R10, PRR3, and RNF113A. Using peptide arrays, we investigated CARNMT1-mediated methylation of 145 candidate sequences, encompassing all C3H ZnFs and selected non-ZnFs. We found that only ∼30% of the tested sequences were methylated, with C3H ZnFs constituting the vast majority of the strongly methylated ones, most of which are also methylated in cells. This establishes peptide methylation as a good predictor of in vivo methylation. To investigate the specificity of CARNMT1, we systematically substituted His-proximal residues in four different substrate peptides. This generated four rather different sequence preference profiles, which were still quite restrictive for each peptide, indicating that substrate sequence recognition by CARNMT1 is context-dependent and that sequence-based prediction of additional CARNMT1 substrates may be challenging. We also identified several homologous methylation events in Caenorhabditis elegans and showed that they could be introduced by nematode CARNMT in vitro. Thus, CARNMT1 is an evolutionarily conserved protein HMT with a complex mode of substrate recognition.

• Falnes, Pål; Malecki, Jedrzej Mieczyslaw; Gonzalez-Molina, Maria del Carmen Herrera; Bengtsen, Mads & Davydova, Erna (2023). Human seven-β-strand (METTL) methyltransferases - conquering the universe of protein lysine methylation. Journal of Biological Chemistry. ISSN 0021-9258. 299(6), p. 1–15. doi: 10.1016/j.jbc.2023.104661. Full text in Research Archive Show summary

  Lysine methylation is an abundant posttranslational modification, which has been most intensively studied in the context of histone proteins, where it represents an important epigenetic mark. Lysine methylation of histone proteins is primarily catalyzed by SET-domain methyltransferases (MTases). However, it has recently become evident that also another MTase family, the so-called seven-β-strand (7BS) MTases, often denoted METTLs (methyltransferase-like), contains several lysine (K)-specific MTases (KMTs). These enzymes catalyze the attachment of up to three methyl groups to lysine residues in specific substrate proteins, using S-adenosylmethionine (AdoMet) as methyl donor. About a decade ago, only a single human 7BS KMT was known, namely the histone-specific DOT1L, but 15 additional 7BS KMTs have now been discovered and characterized. These KMTs typically target a single nonhistone substrate that, in most cases, belongs to one of the following three protein groups: components of the cellular protein synthesis machinery, mitochondrial proteins, and molecular chaperones. This article provides an extensive overview and discussion of the human 7BS KMTs and their biochemical and biological roles.

• Tadele, Dagim Shiferaw; Robertson, Joseph; Crispin, Richard; Herrera, Carmen; Chlubnová, Markéta & Piechaczyk, Laure Isabelle [Show all 14 contributors for this article] (2020). A cell competition-based small molecule screen identifies a novel compound that induces dual c-Myc depletion and p53 activation. Journal of Biological Chemistry. ISSN 0021-9258. 296. doi: 10.1074/jbc.RA120.015285. Full text in Research Archive Show summary

  Breakpoint Cluster Region-Abelson kinase (BCR–Abl) is a driver oncogene that causes chronic myeloid leukemia and a subset of acute lymphoid leukemias. Although tyrosine kinase inhibitors provide an effective treatment for these diseases, they generally do not kill leukemic stem cells (LSCs), the cancer-initiating cells that compete with normal hematopoietic stem cells for the bone marrow niche. New strategies to target cancers driven by BCR–Abl are therefore urgently needed. We performed a small molecule screen based on competition between isogenic untransformed cells and BCR–Abl-transformed cells and identified several compounds that selectively impair the fitness of BCR–Abl-transformed cells. Interestingly, systems-level analysis of one of these novel compounds, DJ34, revealed that it induced depletion of c-Myc and activation of p53. DJ34-mediated c-Myc depletion occurred in a wide range of tumor cell types, including lymphoma, lung, glioblastoma, breast cancer, and several forms of leukemia, with primary LSCs being particularly sensitive to DJ34. Further analyses revealed that DJ34 interferes with c-Myc synthesis at the level of transcription, and we provide data showing that DJ34 is a DNA intercalator and topoisomerase II inhibitor. Physiologically, DJ34 induced apoptosis, cell cycle arrest, and cell differentiation. Taken together, we have identified a novel compound that dually targets c-Myc and p53 in a wide variety of cancers, and with particularly strong activity against LSCs.

• P, Aurélie Nguéa; Robertson, Joseph; Herrera, Maria Carmen; Chymkowitch, Pierre & Enserink, Jorrit (2019). Desumoylation of RNA polymerase III lies at the core of the Sumo stress response in yeast. Journal of Biological Chemistry. ISSN 0021-9258. 294(49), p. 18784–18795. doi: 10.1074/jbc.RA119.009721. Full text in Research Archive Show summary

  Post-translational modification by small ubiquitin-like modifier (Sumo) regulates many cellular processes, including the adaptive response to various types of stress, referred to as the Sumo stress response (SSR). However, it remains unclear whether the SSR involves a common set of core proteins regardless of the type of stress or whether each particular type of stress induces a stress-specific SSR that targets a unique, largely nonoverlapping set of Sumo substrates. In this study, we used MS and a Gene Ontology approach to identify differentially sumoylated proteins during heat stress, hyperosmotic stress, oxidative stress, nitrogen starvation, and DNA alkylation in Saccharomyces cerevisiae cells. Our results indicate that each stress triggers a specific SSR signature centered on proteins involved in transcription, translation, and chromatin regulation. Strikingly, whereas the various stress-specific SSRs were largely nonoverlapping, all types of stress tested here resulted in desumoylation of subunits of RNA polymerase III, which correlated with a decrease in tRNA synthesis. We conclude that desumoylation and subsequent inhibition of RNA polymerase III constitutes the core of all stress-specific SSRs in yeast.

• Herrera, Maria Carmen; Chymkowitch, Pierre; Robertson, Joseph; Eriksson, Jens; Bøe, Stig Ove & Alseth, Ingrun [Show all 7 contributors for this article] (2018). Cdk1 gates cell cycle-dependent tRNA synthesis by regulating RNA polymerase III activity. Nucleic Acids Research (NAR). ISSN 0305-1048. 46(22), p. 11698–11711. doi: 10.1093/nar/gky846. Full text in Research Archive Show summary

  tRNA genes are transcribed by RNA polymerase III (RNAPIII). During recent years it has become clear that RNAPIII activity is strictly regulated by the cell in response to environmental cues and the homeostatic status of the cell. However, the molecular mechanisms that control RNAPIII activity to regulate the amplitude of tDNA transcription in normally cycling cells are not well understood. Here, we show that tRNA levels fluctuate during the cell cycle and reveal an underlying molecular mechanism. The cyclin Clb5 recruits the cyclin dependent kinase Cdk1 to tRNA genes to boost tDNA transcription during late S phase. At tDNA genes, Cdk1 promotes the recruitment of TFIIIC, stimulates the interaction between TFIIIB and TFIIIC, and increases the dynamics of RNA polymerase III in vivo. Furthermore, we identified Bdp1 as a putative Cdk1 substrate in this process. Preventing Bdp1 phosphorylation prevented cell cycle-dependent recruitment of TFIIIC and abolished the cell cycle-dependent increase in tDNA transcription. Our findings demonstrate that under optimal growth conditions Cdk1 gates tRNA synthesis in S phase by regulating the RNAPIII machinery, revealing a direct link between the cell cycle and RNAPIII activity.

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