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Zhang F, Bischof H, Burgstaller S, Bourgeois BMR, Malli R, Madl T. Genetically encoded fluorescent sensor to monitor intracellular arginine methylation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2024; 252:112867. [PMID: 38368636 DOI: 10.1016/j.jphotobiol.2024.112867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 02/03/2024] [Accepted: 02/12/2024] [Indexed: 02/20/2024]
Abstract
Arginine methylation (ArgMet), as a post-translational modification, plays crucial roles in RNA processing, transcriptional regulation, signal transduction, DNA repair, apoptosis and liquid-liquid phase separation (LLPS). Since arginine methylation is associated with cancer pathogenesis and progression, protein arginine methyltransferases have gained interest as targets for anti-cancer therapy. Despite considerable process made to elucidate (patho)physiological mechanisms regulated by arginine methylation, there remains a lack of tools to visualize arginine methylation with high spatiotemporal resolution in live cells. To address this unmet need, we generated an ArgMet-sensitive genetically encoded, Förster resonance energy transfer-(FRET) based biosensor, called GEMS, capable of quantitative real-time monitoring of ArgMet dynamics. We optimized these biosensors by using different ArgMet-binding domains, arginine-glycine-rich regions and adjusting the linkers within the biosensors to improve their performance. Using a set of mammalian cell lines and modulators, we demonstrated the applicability of GEMS for monitoring changes in arginine methylation with single-cell and temporal resolution. The GEMS can facilitate the in vitro screening to find potential protein arginine methyltransferase inhibitors and will contribute to a better understanding of the regulation of ArgMet related to differentiation, development and disease.
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Affiliation(s)
- Fangrong Zhang
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou 350122, China; Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Helmut Bischof
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Sandra Burgstaller
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Benjamin M R Bourgeois
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; Otto Loewi Research Center, Medicinal Chemistry, Medical University of Graz, 8010 Graz, Austria
| | - Roland Malli
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; BioTechMed-Graz, 8010 Graz, Austria
| | - Tobias Madl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; Otto Loewi Research Center, Medicinal Chemistry, Medical University of Graz, 8010 Graz, Austria; BioTechMed-Graz, 8010 Graz, Austria.
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2
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He S, Valkov E, Cheloufi S, Murn J. The nexus between RNA-binding proteins and their effectors. Nat Rev Genet 2023; 24:276-294. [PMID: 36418462 DOI: 10.1038/s41576-022-00550-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2022] [Indexed: 11/25/2022]
Abstract
RNA-binding proteins (RBPs) regulate essentially every event in the lifetime of an RNA molecule, from its production to its destruction. Whereas much has been learned about RNA sequence specificity and general functions of individual RBPs, the ways in which numerous RBPs instruct a much smaller number of effector molecules, that is, the core engines of RNA processing, as to where, when and how to act remain largely speculative. Here, we survey the known modes of communication between RBPs and their effectors with a particular focus on converging RBP-effector interactions and their roles in reducing the complexity of RNA networks. We discern the emerging unifying principles and discuss their utility in our understanding of RBP function, regulation of biological processes and contribution to human disease.
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Affiliation(s)
- Shiyang He
- Department of Biochemistry, University of California, Riverside, CA, USA
- Center for RNA Biology and Medicine, Riverside, CA, USA
| | - Eugene Valkov
- RNA Biology Laboratory & Center for Structural Biology, Center for Cancer Research, National Cancer Institute (NCI), Frederick, MD, USA
| | - Sihem Cheloufi
- Department of Biochemistry, University of California, Riverside, CA, USA.
- Center for RNA Biology and Medicine, Riverside, CA, USA.
- Stem Cell Center, University of California, Riverside, CA, USA.
| | - Jernej Murn
- Department of Biochemistry, University of California, Riverside, CA, USA.
- Center for RNA Biology and Medicine, Riverside, CA, USA.
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3
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Roy R, Rajyaguru PI. Assay to Study the Phase-transition Behavior of Edc3, a Conserved Processing Body (P-body) Marker Protein. Bio Protoc 2022; 12:e4487. [PMID: 36199703 PMCID: PMC9486690 DOI: 10.21769/bioprotoc.4487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 07/03/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022] Open
Abstract
RNA granules are conserved, non-membranous, biphasic structures predominantly composed of RNA and RNA-binding proteins. RNA granules often assemble as a result of cellular responses to a variety of stresses, including infection. Two types of RNA granules are best characterized: stress granules (SGs) and processing bodies (P-bodies). The mechanism of RNA granule assembly and disassembly is still understudied because of its complex composition and dynamic behavior. The assembly of RNA granules is driven by a process known as phase separation of granule components. Edc3 is a conserved decapping activator and an essential P-body component in Saccharomyces cerevisiae. Phase separation of P-body proteins has been poorly explored. This protocol will enable the visualization of the phase transition behavior of Edc3, since it is tagged to mCherry. It further describes using small molecules and other proteins to study P-body dynamics. In addition to the assembly of Edc3, this assay also lays the foundation to study disassembly of phase-separated assemblies in vitro , which was not explored earlier. We have devised the assay to describe the use of one such protein that acts as a disassembly factor. Overall, this protocol is simple to perform and can potentially be combined with analyzing these assemblies using other approaches. Graphical abstract.
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Affiliation(s)
- Raju Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Purusharth I. Rajyaguru
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
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*For correspondence:
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4
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Roy R, Das G, Kuttanda IA, Bhatter N, Rajyaguru PI. Low complexity RGG-motif sequence is required for Processing body (P-body) disassembly. Nat Commun 2022; 13:2077. [PMID: 35440550 PMCID: PMC9019020 DOI: 10.1038/s41467-022-29715-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 03/21/2022] [Indexed: 01/12/2023] Open
Abstract
P-bodies are conserved mRNP complexes that are implicated in determining mRNA fate by affecting translation and mRNA decay. In this report, we identify RGG-motif containing translation repressor protein Sbp1 as a disassembly factor of P-bodies since disassembly of P-bodies is defective in Δsbp1. RGG-motif is necessary and sufficient to rescue the PB disassembly defect in Δsbp1. Binding studies using purified proteins revealed that Sbp1 physically interacts with Edc3 and Sbp1-Edc3 interaction competes with Edc3-Edc3 interaction. Purified Edc3 forms assemblies, promoted by the presence of RNA and NADH and the addition of purified Sbp1, but not the RGG-deletion mutant, leads to significantly decreased Edc3 assemblies. We further note that the aggregates of human EWSR1 protein, implicated in neurodegeneration, are more persistent in the absence of Sbp1 and overexpression of EWSR1 in Δsbp1 leads to a growth defect. Taken together, our observations suggest a role of Sbp1 in disassembly, which could apply to disease-relevant heterologous protein-aggregates.
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Affiliation(s)
- Raju Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Gitartha Das
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | | | - Nupur Bhatter
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
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5
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Zeke A, Schád É, Horváth T, Abukhairan R, Szabó B, Tantos A. Deep structural insights into RNA-binding disordered protein regions. WILEY INTERDISCIPLINARY REVIEWS. RNA 2022; 13:e1714. [PMID: 35098694 PMCID: PMC9539567 DOI: 10.1002/wrna.1714] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 12/22/2021] [Accepted: 01/07/2022] [Indexed: 12/11/2022]
Abstract
Recent efforts to identify RNA binding proteins in various organisms and cellular contexts have yielded a large collection of proteins that are capable of RNA binding in the absence of conventional RNA recognition domains. Many of the recently identified RNA interaction motifs fall into intrinsically disordered protein regions (IDRs). While the recognition mode and specificity of globular RNA binding elements have been thoroughly investigated and described, much less is known about the way IDRs can recognize their RNA partners. Our aim was to summarize the current state of structural knowledge on the RNA binding modes of disordered protein regions and to propose a classification system based on their sequential and structural properties. Through a detailed structural analysis of the complexes that contain disordered protein regions binding to RNA, we found two major binding modes that represent different recognition strategies and, most likely, functions. We compared these examples with DNA binding disordered proteins and found key differences stemming from the nucleic acids as well as similar binding strategies, implying a broader substrate acceptance by these proteins. Due to the very limited number of known structures, we integrated molecular dynamics simulations in our study, whose results support the proposed structural preferences of specific RNA‐binding IDRs. To broaden the scope of our review, we included a brief analysis of RNA‐binding small molecules and compared their structural characteristics and RNA recognition strategies to the RNA‐binding IDRs. This article is categorized under:RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Interactions with Proteins and Other Molecules > Protein–RNA Recognition RNA Interactions with Proteins and Other Molecules > Small Molecule–RNA Interactions
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Affiliation(s)
- András Zeke
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Éva Schád
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Tamás Horváth
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Rawan Abukhairan
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Beáta Szabó
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Agnes Tantos
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
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6
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Bhatter N, Iyyappan R, Mohanan G, Rajyaguru PI. Exploring the role of RRM domains and conserved aromatic residues in RGG motif of eIF4G-binding translation repressor protein Sbp1. Wellcome Open Res 2021; 3:102. [PMID: 32175478 PMCID: PMC7059846 DOI: 10.12688/wellcomeopenres.14709.3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2021] [Indexed: 11/20/2022] Open
Abstract
Background: RNA binding proteins play crucial role in determining if a given mRNA will be translated, stored, or degraded. Sbp1 is an RGG-motif containing protein that is implicated in affecting mRNA decapping and translation. Sbp1 represses translation by binding eIF4G1 through its RGG-motif and activates decapping when overexpressed. In this report, we have assessed the genetic interaction of Sbp1 with decapping activators such as Dhh1, Pat1, and Scd6. We have further analyzed the importance of different domains and specific conserved residues of Sbp1 in its ability to cause over-expression mediated growth defect. Method: Sequence alignment was performed to identify conserved aromatic residues to be mutated. Using site-directed mutagenesis several point mutations and domain deletions were created in Sbp1 expressed under a galactose-inducible promoter. The mutants were tested for their ability to cause growth defect upon over-expression. The ability of Sbp1 to affect over-expression mediated growth defect of other decapping activators was tested using growth assay. Live cell imaging was done to study localization of Sbp1 and its RRM-deletion mutants to RNA granules upon glucose starvation. Results: Mutation of several aromatic residues in the RGG-motif and that of the phosphorylation sites in the RRM domain of Sbp1 did not affect the growth defect phenotype. Deletion of another eIF4G1-binding RGG-motif protein Scd6 does not affect the ability of Sbp1 to cause growth defect. Moreover, absence of Sbp1 did not affect the growth defect phenotypes observed upon overexpression of decapping activators Dhh1 and Pat1. Strikingly deletion of both the RRM domains (RRM1 and RRM2) and not the RNP motifs within them compromised the growth defect phenotype. Sbp1 mutant lacking both RRM1 and RRM2 was highly defective in localizing to RNA granules. Conclusion: This study identifies an important role of RRM domains independent of the RNP motif in Sbp1 function.
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Affiliation(s)
- Nupur Bhatter
- Department of Biochemistry, Indian Institute of Science, CV Raman Road, Bangalore, 560012, India
| | - Rajan Iyyappan
- Institute of Animal Physiology and Genetics, Libechov, Czech Republic
| | - Gayatri Mohanan
- Department of Biochemistry, Indian Institute of Science, CV Raman Road, Bangalore, 560012, India
| | - Purusharth I Rajyaguru
- Department of Biochemistry, Indian Institute of Science, CV Raman Road, Bangalore, 560012, India
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7
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Zhang F, Kerbl-Knapp J, Rodriguez Colman MJ, Meinitzer A, Macher T, Vujić N, Fasching S, Jany-Luig E, Korbelius M, Kuentzel KB, Mack M, Akhmetshina A, Pirchheim A, Paar M, Rinner B, Hörl G, Steyrer E, Stelzl U, Burgering B, Eisenberg T, Pertschy B, Kratky D, Madl T. Global analysis of protein arginine methylation. CELL REPORTS METHODS 2021; 1:100016. [PMID: 35475236 PMCID: PMC9017121 DOI: 10.1016/j.crmeth.2021.100016] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/02/2021] [Accepted: 05/12/2021] [Indexed: 12/25/2022]
Abstract
Quantitative information about the levels and dynamics of post-translational modifications (PTMs) is critical for an understanding of cellular functions. Protein arginine methylation (ArgMet) is an important subclass of PTMs and is involved in a plethora of (patho)physiological processes. However, because of the lack of methods for global analysis of ArgMet, the link between ArgMet levels, dynamics, and (patho)physiology remains largely unknown. We utilized the high sensitivity and robustness of nuclear magnetic resonance (NMR) spectroscopy to develop a general method for the quantification of global protein ArgMet. Our NMR-based approach enables the detection of protein ArgMet in purified proteins, cells, organoids, and mouse tissues. We demonstrate that the process of ArgMet is a highly prevalent PTM and can be modulated by small-molecule inhibitors and metabolites and changes in cancer and during aging. Thus, our approach enables us to address a wide range of biological questions related to ArgMet in health and disease.
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Affiliation(s)
- Fangrong Zhang
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Jakob Kerbl-Knapp
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Maria J. Rodriguez Colman
- Oncode Institute and Department of Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands
| | - Andreas Meinitzer
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, 8010 Graz, Austria
| | - Therese Macher
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Nemanja Vujić
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
| | - Sandra Fasching
- Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria
| | - Evelyne Jany-Luig
- Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria
| | - Melanie Korbelius
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Katharina B. Kuentzel
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Maximilian Mack
- BioTechMed-Graz, 8010 Graz, Austria
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Alena Akhmetshina
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Anita Pirchheim
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Margret Paar
- Otto-Loewi Research Center, Physiological Chemistry, Medical University of Graz, 8010 Graz, Austria
| | - Beate Rinner
- Division of Biomedical Research, Medical University of Graz, 8036 Graz, Austria
| | - Gerd Hörl
- Otto-Loewi Research Center, Physiological Chemistry, Medical University of Graz, 8010 Graz, Austria
| | - Ernst Steyrer
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
| | - Ulrich Stelzl
- BioTechMed-Graz, 8010 Graz, Austria
- Institute of Pharmaceutical Sciences, University of Graz, 8010 Graz, Austria
| | - Boudewijn Burgering
- Oncode Institute and Department of Molecular Cancer Research, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX Utrecht, the Netherlands
| | - Tobias Eisenberg
- BioTechMed-Graz, 8010 Graz, Austria
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Brigitte Pertschy
- BioTechMed-Graz, 8010 Graz, Austria
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
- Field of Excellence BioHealth – University of Graz, Graz, Austria
| | - Dagmar Kratky
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
| | - Tobias Madl
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
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8
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Mohanan G, Das A, Rajyaguru PI. Genotoxic stress response: What is the role of cytoplasmic mRNA fate? Bioessays 2021; 43:e2000311. [PMID: 34096096 DOI: 10.1002/bies.202000311] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 05/15/2021] [Accepted: 05/18/2021] [Indexed: 12/18/2022]
Abstract
Genotoxic stress leads to DNA damage which can be detrimental to the cell. A well-orchestrated cellular response is mounted to manage and repair the genotoxic stress-induced DNA damage. Our understanding of genotoxic stress response is derived mainly from studies focused on transcription, mRNA splicing, and protein turnover. Surprisingly not as much is understood about the role of mRNA translation and decay in genotoxic stress response. This is despite the fact that regulation of gene expression at the level of mRNA translation and decay plays a critical role in a myriad of cellular processes. This review aims to summarize some of the known findings of the role of mRNA translation and decay by focusing on two categories of examples. We discuss examples of mRNA whose fates are regulated in the cytoplasm and RNA-binding proteins that regulate mRNA fates in response to genotoxic stress.
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Affiliation(s)
- Gayatri Mohanan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Amiyaranjan Das
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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9
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Parbin S, Damodharan S, Rajyaguru PI. Arginine methylation and cytoplasmic mRNA fate: An exciting new partnership. Yeast 2021; 38:441-452. [PMID: 34048611 DOI: 10.1002/yea.3653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 05/12/2021] [Accepted: 05/20/2021] [Indexed: 12/22/2022] Open
Abstract
Posttranslational modifications play a crucial role in regulating gene expression. Among these modifications, arginine methylation has recently attracted tremendous attention due to its role in multiple cellular functions. This review discusses the recent advances that have established arginine methylation as a major player in determining cytoplasmic messenger RNA (mRNA) fate. We specifically focus on research that implicates arginine methylation in regulating mRNA translation, decay, and RNA granule dynamics. Based on this research, we highlight a few emerging future avenues that will lead to exciting discoveries in this field.
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Affiliation(s)
- Sabnam Parbin
- Department of Biochemistry, Indian Institute of Science, Bangalore, India.,Integrative Genomics Core Unit, University Medical Centre, Göttingen, Göttingen, Germany
| | - Subha Damodharan
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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10
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Poornima G, Srivastava G, Roy B, Kuttanda IA, Kurbah I, Rajyaguru PI. RGG-motif containing mRNA export factor Gbp2 acts as a translation repressor. RNA Biol 2021; 18:2342-2353. [PMID: 33910495 DOI: 10.1080/15476286.2021.1910403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Complex cascades of RNA-binding proteins regulate the mRNA metabolism and influence gene expression. Several distinct proteins act at different stages of mRNA life cycle. SR family proteins in yeast are implicated in mRNA processing and nuclear export. In this report, we uncover the role of an SR/RGG-motif containing mRNA export factor Gbp2 in mRNA translation regulation. We demonstrate that Gbp2 localizes to cytoplasmic granules upon heat shock and oxidative stress. Our pull-down assays demonstrate that Gbp2 directly binds to the conserved translation factor eIF4G1 via its RGG motif. We further mapped the region on eIF4G1 to which Gbp2 binds and observed that the binding region overlaps with another translation repressor Sbp1. We found that the RGG-motif deletion mutant is defective in localizing to polysome fractions. Upon tethering Gbp2 to a GFP reporter mRNA in vivo, translation of GFP reporter decreased significantly indicating that Gbp2 acts as a translation repressor. Consistent with these results, we show that Gbp2 can directly repress mRNA translation in the in vitro translation systems in an RGG-motif dependent manner. Taken together, our results establish that the mRNA export factor Gbp2 has a vital role in repressing translation of mRNA. We propose that Gbp2 is a multifaceted RGG-motif protein responsible for translational repression without affecting mRNA levels.
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Affiliation(s)
| | - Gaurav Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Brinta Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | - Iladeiti Kurbah
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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11
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Hamey JJ, Nguyen A, Wilkins MR. Discovery of Arginine Methylation, Phosphorylation, and Their Co-occurrence in Condensate-Associated Proteins in Saccharomyces cerevisiae. J Proteome Res 2021; 20:2420-2434. [PMID: 33856219 DOI: 10.1021/acs.jproteome.0c00927] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The formation of condensates in membraneless organelles is thought to be driven by protein phase separation. Arginine methylation and serine/threonine phosphorylation are important in the phase separation process; however, these post-translational modifications are often present in intrinsically disordered regions that are difficult to analyze with standard proteomic techniques. To understand their presence and co-occurrence in condensate-associated proteins, here, we use a multiprotease and multi-tandem mass spectrometry (MS/MS) fragmentation approach, coupled with heavy methyl stable isotope labeling of amino acids in cell culture (SILAC) and phospho- or methyl-peptide enrichment. For Saccharomyces cerevisiae, we report a 50% increase in the known arginine methylproteome, involving 15 proteins that are all condensate-associated. Importantly, some of these proteins have arginine methylation on all predicted sites-providing evidence that this modification can be pervasive. We explored whether arginine-methylated, condensate-associated proteins are also phosphorylated and found 12 such proteins to carry phosphorylated serine or threonine. In Npl3, Ded1, and Sbp1, single peptides were found to carry both modifications, indicating a co-occurrence in close proximity and on the same protein molecule. These co-modifications occur in regions of disorder, whereas arginine methylation is typically on regions of disorder that are also basic. For phosphorylation, its association with charged regions of condensate-associated proteins was less consistent, although some regions with multisite phosphorylation sites were strongly acidic. We conclude that arginine-methylated proteins associated with condensates are typically also modified with protein phosphorylation.
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Affiliation(s)
- Joshua J Hamey
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Amy Nguyen
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Marc R Wilkins
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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12
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Garg M, Poornima G, Rajyaguru PI. Elucidation of the RNA-granule inducing sodium azide stress response through transcriptome analysis. Genomics 2020; 112:2978-2989. [PMID: 32437849 PMCID: PMC7116212 DOI: 10.1016/j.ygeno.2020.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/30/2020] [Accepted: 05/01/2020] [Indexed: 12/27/2022]
Abstract
Sodium azide is a commonly used cytochrome oxidase inhibitor that leads to translation repression and RNA granule assembly. The global changes in mRNA abundance in response to this stressor are unknown. RGG-motif proteins Scd6 and Sbp1 are translation-repressors and decapping-activators that localize to and affect the assembly of RNA granules in response to sodium azide stress. Transcriptome-wide effects of these proteins remain unknown. To address this, we have sequenced transcriptome of the: a) wild type strain under unstressed and sodium azide stress, b) Δscd6 and Δsbp1 strains under unstressed and sodium azide stress. Transcriptome analysis identified altered abundance of many transcripts belonging to stress-responsive pathways which were further validated by qRT-PCR results. Abundance of several transcripts was altered in Δscd6/Δsbp1 under normal conditions and upon stress. Overall, this study provides critical insights into transcriptome changes in response to sodium azide stress and the role of RGG-motif proteins in these changes.
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Affiliation(s)
- Mani Garg
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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Bhatter N, Iyyappan R, Rajyaguru PI. Exploring the role of RRM domains and conserved aromatic residues in RGG motif of eIF4G-binding translation repressor protein Sbp1. Wellcome Open Res 2020; 3:102. [DOI: 10.12688/wellcomeopenres.14709.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/28/2020] [Indexed: 11/20/2022] Open
Abstract
Background: Mechanisms of mRNA fate decisions play an important role in determining if a given mRNA will be translated, stored or degraded upon arrival to cytoplasm. Sbp1 is an important RGG-motif containing protein that is implicated in affecting mRNA decapping and translation. Sbp1 represses translation by binding eIF4G1 through its RGG-motif and activates decapping when overexpressed. In this report we have assessed the genetic interaction of Sbp1 with decapping activators such as Dhh1, Pat1 and Scd6. We have further analyzed the importance of different domains and specific conserved residues of Sbp1 in translation repression activity. Method: Sequence alignment was performed to identify conserved aromatic residues to be mutated. Using site-directed mutagenesis several point mutations and domain deletions was created in Sbp1 expressed under a galactose-inducible promoter. The mutants were tested for their ability to cause growth defect upon over-expression. The ability of Sbp1 to affect over expression mediated growth defect of other decapping activators was tested using growth assay. Live cell imaging was done to study localization of Sbp1 and its RRM-deletion mutants to RNA granules upon glucose starvation. Results: Mutation of several aromatic residues in the RGG-motif and that of the phosphorylation sites in the RRM domain of Sbp1 did not affect the growth defect phenotype. Deletion of another eIF4G1-binding RGG-motif protein Scd6 does not affect the ability of Sbp1 to cause growth defect. Moreover, absence of Sbp1 did not affect the growth defect phenotypes observed upon overexpression of decapping activators Dhh1 and Pat1. Strikingly deletion of both the RRM domains (RRM1 and RRM2) and not the RNP motifs within them compromised the growth defect phenotype. Sbp1 mutant lacking both RRM1 and RRM2 was highly defective in localizing to RNA granules. Conclusion: This study identifies an important role of RRM domains independent of RNP motif in Sbp1 repression activity.
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DEKTV and YVG motifs in the Lsm domain are important for the activity of Scd6, a conserved translation repressor protein. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194474. [PMID: 31926930 DOI: 10.1016/j.bbagrm.2019.194474] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 12/17/2019] [Accepted: 12/17/2019] [Indexed: 12/29/2022]
Abstract
Scd6 is a conserved RGG-motif protein which represses translation by binding eIF4G through its RGG-motif. Lsm and FDF are two other conserved domains present in the protein, however the role of both these domains is unclear. We provide evidence in this report that the Lsm domain is important for the role of Scd6 in translation. Mutant of Scd6 lacking the Lsm domain does not cause overexpression growth defect in a manner comparable to the wild type. Similar results were observed with two distinct point mutants of Scd6 wherein putative RNA-binding motifs DxEKxTV and YVG were mutated. Upon overexpression, the three mutants were defective in inducing formation of P-bodies and stress granules which are conserved sites of translation repression. Importantly localization to granules in response to glucose deprivation and sodium azide stress was defective for Lsm domain mutants indicating that the inability to localize to granules could be a reason for their defective role in translation. Deletion of scd6 impairs Lsm1 foci formation upon glucose deprivation stress which could not be rescued by complementation with Lsm-domain deletion mutant of Scd6 when compared to the full-length protein. Put together, our results highlight the role of Lsm domain and its specific motifs in Scd6 activity and provide crucial insight into its function.
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