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Li Y, Wang Q, Xu Y, Li Z. Structures of co-transcriptional RNA capping enzymes on paused transcription complex. Nat Commun 2024; 15:4622. [PMID: 38816438 PMCID: PMC11139899 DOI: 10.1038/s41467-024-48963-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 05/17/2024] [Indexed: 06/01/2024] Open
Abstract
The 5'-end capping of nascent pre-mRNA represents the initial step in RNA processing, with evidence demonstrating that guanosine addition and 2'-O-ribose methylation occur in tandem with early steps of transcription by RNA polymerase II, especially at the pausing stage. Here, we determine the cryo-EM structures of the paused elongation complex in complex with RNGTT, as well as the paused elongation complex in complex with RNGTT and CMTR1. Our findings show the simultaneous presence of RNGTT and the NELF complex bound to RNA polymerase II. The NELF complex exhibits two conformations, one of which shows a notable rearrangement of NELF-A/D compared to that of the paused elongation complex. Moreover, CMTR1 aligns adjacent to RNGTT on the RNA polymerase II stalk. Our structures indicate that RNGTT and CMTR1 directly bind the paused elongation complex, illuminating the mechanism by which 5'-end capping of pre-mRNA during transcriptional pausing.
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Affiliation(s)
- Yan Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Qianmin Wang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Ze Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, 200032, China.
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China.
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2
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Aranega AE, Franco D. Posttranscriptional Regulation by Proteins and Noncoding RNAs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:313-339. [PMID: 38884719 DOI: 10.1007/978-3-031-44087-8_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Posttranscriptional regulation comprises those mechanisms occurring after the initial copy of the DNA sequence is transcribed into an intermediate RNA molecule (i.e., messenger RNA) until such a molecule is used as a template to generate a protein. A subset of these posttranscriptional regulatory mechanisms essentially are destined to process the immature mRNA toward its mature form, conferring the adequate mRNA stability, providing the means for pertinent introns excision, and controlling mRNA turnover rate and quality control check. An additional layer of complexity is added in certain cases, since discrete nucleotide modifications in the mature RNA molecule are added by RNA editing, a process that provides large mature mRNA diversity. Moreover, a number of posttranscriptional regulatory mechanisms occur in a cell- and tissue-specific manner, such as alternative splicing and noncoding RNA-mediated regulation. In this chapter, we will briefly summarize current state-of-the-art knowledge of general posttranscriptional mechanisms, while major emphases will be devoted to those tissue-specific posttranscriptional modifications that impact on cardiac development and congenital heart disease.
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Affiliation(s)
- Amelia E Aranega
- Cardiovascular Research Group, Department of Experimental Biology, University of Jaén, Jaén, Spain
| | - Diego Franco
- Cardiovascular Research Group, Department of Experimental Biology, University of Jaén, Jaén, Spain.
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3
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Interplay of mRNA capping and transcription machineries. Biosci Rep 2021; 40:221784. [PMID: 31904821 PMCID: PMC6981093 DOI: 10.1042/bsr20192825] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/02/2020] [Accepted: 01/06/2020] [Indexed: 12/31/2022] Open
Abstract
Early stages of transcription from eukaryotic promoters include two principal events: the capping of newly synthesized mRNA and the transition of RNA polymerase II from the preinitiation complex to the productive elongation state. The capping checkpoint model implies that these events are tightly coupled, which is necessary for ensuring the proper capping of newly synthesized mRNA. Recent findings also show that the capping machinery has a wider effect on transcription and the entire gene expression process. The molecular basis of these phenomena is discussed.
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4
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Richard S, Gross L, Fischer J, Bendalak K, Ziv T, Urim S, Choder M. Numerous Post-translational Modifications of RNA Polymerase II Subunit Rpb4/7 Link Transcription to Post-transcriptional Mechanisms. Cell Rep 2021; 34:108578. [PMID: 33440147 DOI: 10.1016/j.celrep.2020.108578] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 07/24/2020] [Accepted: 12/09/2020] [Indexed: 01/25/2023] Open
Abstract
Rpb4/7 binds RNA polymerase II (RNA Pol II) transcripts co-transcriptionally and accompanies them throughout their lives. By virtue of its capacity to interact with key regulators (e.g., RNA Pol II, eIF3, and Pat1) temporally and spatially, Rpb4/7 regulates the major stages of the mRNA life cycle. Here we show that Rpb4/7 can undergo more than 100 combinations of post-translational modifications (PTMs). Remarkably, the Rpb4/7 PTM repertoire changes as the mRNA/Rpb4/7 complex progresses from one stage to the next. These temporal PTMs regulate Rpb4 interactions with key regulators of gene expression that control transcriptional and post-transcriptional stages. Moreover, one mutant type specifically affects mRNA synthesis, whereas the other affects mRNA synthesis and decay; both types disrupt the balance between mRNA synthesis and decay ("mRNA buffering") and the cell's capacity to respond to the environment. We propose that temporal Rpb4/7 PTMs mediate the cross-talk among the various stages of the mRNA life cycle.
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Affiliation(s)
- Stephen Richard
- Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Lital Gross
- Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Jonathan Fischer
- Computer Science Division, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Keren Bendalak
- Smoler Proteomics Center, Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Tamar Ziv
- Smoler Proteomics Center, Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Shira Urim
- Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Mordechai Choder
- Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel.
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5
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The capping enzyme facilitates promoter escape and assembly of a follow-on preinitiation complex for reinitiation. Proc Natl Acad Sci U S A 2019; 116:22573-22582. [PMID: 31591205 DOI: 10.1073/pnas.1905449116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
After synthesis of a short nascent RNA, RNA polymerase II (pol II) dissociates general transcription factors (GTFs; TFIIA, TFIIB, TBP, TFIIE, TFIIF, and TFIIH) and escapes the promoter, but many of the mechanistic details of this process remain unclear. Here we developed an in vitro transcription system from the yeast Saccharomyces cerevisiae that allows conversion of the preinitiation complex (PIC) to bona fide initially transcribing complex (ITC), elongation complex (EC), and reinitiation complex (EC+ITC). By biochemically isolating postinitiation complexes stalled at different template positions, we have determined the timing of promoter escape and the composition of protein complexes associated with different lengths of RNA. Almost all of the postinitiation complexes retained the GTFs when pol II was stalled at position +27 relative to the transcription start site, whereas most complexes had completed promoter escape when stalled at +49. This indicates that GTFs remain associated with pol II much longer than previously expected. Nevertheless, the long-persisting transcription complex containing RNA and all of the GTFs is unstable and is susceptible to extensive backtracking of pol II. Addition of the capping enzyme and/or Spt4/5 significantly increased the frequency of promoter escape as well as assembly of a follow-on PIC at the promoter for reinitiation. These data indicate that elongation factors play an important role in promoter escape and that ejection of TFIIB from the RNA exit tunnel of pol II by the growing nascent RNA is not sufficient to complete promoter escape.
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6
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Noe Gonzalez M, Sato S, Tomomori-Sato C, Conaway JW, Conaway RC. CTD-dependent and -independent mechanisms govern co-transcriptional capping of Pol II transcripts. Nat Commun 2018; 9:3392. [PMID: 30139934 PMCID: PMC6107522 DOI: 10.1038/s41467-018-05923-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 08/02/2018] [Indexed: 01/11/2023] Open
Abstract
Co-transcriptional capping of RNA polymerase II (Pol II) transcripts by capping enzyme proceeds orders of magnitude more efficiently than capping of free RNA. Previous studies brought to light a role for the phosphorylated Pol II carboxyl-terminal domain (CTD) in activation of co-transcriptional capping; however, CTD phosphorylation alone could not account for the observed magnitude of activation. Here, we exploit a defined Pol II transcription system that supports both CTD phosphorylation and robust activation of capping to dissect the mechanism of co-transcriptional capping. Taken together, our findings identify a CTD-independent, but Pol II-mediated, mechanism that functions in parallel with CTD-dependent processes to ensure optimal capping, and they support a “tethering” model for the mechanism of activation. The co-transcriptional capping of transcripts synthesized by RNA Pol II is substantially more efficient than capping of free RNA, a process that has been shown to depend on CTD phosphorylation. Here the authors demonstrate that a CTD-independent mechanism functions in parallel with CTD-dependent processes to ensure efficient capping.
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Affiliation(s)
- Melvin Noe Gonzalez
- Stowers Institute for Medical Research, 1000 E 50 th Street, Kansas City, MO, 64110, USA
| | - Shigeo Sato
- Stowers Institute for Medical Research, 1000 E 50 th Street, Kansas City, MO, 64110, USA
| | - Chieri Tomomori-Sato
- Stowers Institute for Medical Research, 1000 E 50 th Street, Kansas City, MO, 64110, USA
| | - Joan W Conaway
- Stowers Institute for Medical Research, 1000 E 50 th Street, Kansas City, MO, 64110, USA.,Department of Biochemistry and Molecular Biology, Kansas University Medical Center, Kansas City, KS, 66160, USA
| | - Ronald C Conaway
- Stowers Institute for Medical Research, 1000 E 50 th Street, Kansas City, MO, 64110, USA. .,Department of Biochemistry and Molecular Biology, Kansas University Medical Center, Kansas City, KS, 66160, USA.
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7
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Zander G, Krebber H. Quick or quality? How mRNA escapes nuclear quality control during stress. RNA Biol 2017; 14:1642-1648. [PMID: 28708448 PMCID: PMC5731798 DOI: 10.1080/15476286.2017.1345835] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/19/2017] [Accepted: 06/20/2017] [Indexed: 10/19/2022] Open
Abstract
Understanding the mechanisms for mRNA production under normal conditions and in response to cytotoxic stresses has been subject of numerous studies for several decades. The shutdown of canonical mRNA transcription, export and translation is required to have enough free resources for the immediate production of heat shock proteins that act as chaperones to sustain cellular processes. In recent work we uncovered a simple mechanism, in which the export block of regular mRNAs and a fast export of heat shock mRNAs is achieved by deactivation of the nuclear mRNA quality control mediated by the guard proteins. In this point of view we combine long known data with recently gathered information that support this novel model, in which cells omit quality control of stress responsive transcripts to ensure survival.
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Affiliation(s)
- Gesa Zander
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August Universität Göttingen, Göttingen, Germany
| | - Heike Krebber
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August Universität Göttingen, Göttingen, Germany
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8
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Sdano MA, Fulcher JM, Palani S, Chandrasekharan MB, Parnell TJ, Whitby FG, Formosa T, Hill CP. A novel SH2 recognition mechanism recruits Spt6 to the doubly phosphorylated RNA polymerase II linker at sites of transcription. eLife 2017; 6:28723. [PMID: 28826505 PMCID: PMC5599234 DOI: 10.7554/elife.28723] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/11/2017] [Indexed: 01/01/2023] Open
Abstract
We determined that the tandem SH2 domain of S. cerevisiae Spt6 binds the linker region of the RNA polymerase II subunit Rpb1 rather than the expected sites in its heptad repeat domain. The 4 nM binding affinity requires phosphorylation at Rpb1 S1493 and either T1471 or Y1473. Crystal structures showed that pT1471 binds the canonical SH2 pY site while pS1493 binds an unanticipated pocket 70 Å distant. Remarkably, the pT1471 phosphate occupies the phosphate-binding site of a canonical pY complex, while Y1473 occupies the position of a canonical pY side chain, with the combination of pT and Y mimicking a pY moiety. Biochemical data and modeling indicate that pY1473 can form an equivalent interaction, and we find that pT1471/pS1493 and pY1473/pS1493 combinations occur in vivo. ChIP-seq and genetic analyses demonstrate the importance of these interactions for recruitment of Spt6 to sites of transcription and for the maintenance of repressive chromatin.
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Affiliation(s)
- Matthew A Sdano
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - James M Fulcher
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Sowmiya Palani
- Department of Radiation Oncology, University of Utah School of Medicine, Salt Lake City, United States.,Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, United States
| | - Mahesh B Chandrasekharan
- Department of Radiation Oncology, University of Utah School of Medicine, Salt Lake City, United States.,Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, United States
| | - Timothy J Parnell
- Department of Radiation Oncology, University of Utah School of Medicine, Salt Lake City, United States.,Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, United States.,Department of Oncological Sciences, University of Utah School of Medicine, Salt Lake City, United States
| | - Frank G Whitby
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Tim Formosa
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
| | - Christopher P Hill
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, United States
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9
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Wendte JM, Pikaard CS. The RNAs of RNA-directed DNA methylation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:140-148. [PMID: 27521981 DOI: 10.1016/j.bbagrm.2016.08.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/05/2016] [Accepted: 08/06/2016] [Indexed: 10/21/2022]
Abstract
RNA-directed chromatin modification that includes cytosine methylation silences transposable elements in both plants and mammals, contributing to genome defense and stability. In Arabidopsis thaliana, most RNA-directed DNA methylation (RdDM) is guided by small RNAs derived from double-stranded precursors synthesized at cytosine-methylated loci by nuclear multisubunit RNA Polymerase IV (Pol IV), in close partnership with the RNA-dependent RNA polymerase, RDR2. These small RNAs help keep transposons transcriptionally inactive. However, if transposons escape silencing, and are transcribed by multisubunit RNA polymerase II (Pol II), their mRNAs can be recognized and degraded, generating small RNAs that can also guide initial DNA methylation, thereby enabling subsequent Pol IV-RDR2 recruitment. In both pathways, the small RNAs find their target sites by interacting with longer noncoding RNAs synthesized by multisubunit RNA Polymerase V (Pol V). Despite a decade of progress, numerous questions remain concerning the initiation, synthesis, processing, size and features of the RNAs that drive RdDM. Here, we review recent insights, questions and controversies concerning RNAs produced by Pols IV and V, and their functions in RdDM. We also provide new data concerning Pol V transcript 5' and 3' ends. This article is part of a Special Issue entitled: Plant Gene Regulatory Mechanisms and Networks. This article is part of a Special Issue entitled: Plant Gene Regulatory Mechanisms and Networks, edited by Dr. Erich Grotewold and Dr. Nathan Springer.
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Affiliation(s)
- Jered M Wendte
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, 915 E. Third Street, Bloomington, IN 47405, USA
| | - Craig S Pikaard
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, 915 E. Third Street, Bloomington, IN 47405, USA; Howard Hughes Medical Institute, Indiana University, Bloomington, IN 47405, USA.
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10
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Molecular Basis of Transcription-Coupled Pre-mRNA Capping. Mol Cell 2015; 58:1079-89. [PMID: 25959396 DOI: 10.1016/j.molcel.2015.04.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 02/27/2015] [Accepted: 03/31/2015] [Indexed: 12/17/2022]
Abstract
Capping is the first step in pre-mRNA processing, and the resulting 5'-RNA cap is required for mRNA splicing, export, translation, and stability. Capping is functionally coupled to transcription by RNA polymerase (Pol) II, but the coupling mechanism remains unclear. We show that efficient binding of the capping enzyme (CE) to transcribing, phosphorylated yeast Pol II (Pol IIp) requires nascent RNA with an unprocessed 5'-triphosphate end. The transcribing Pol IIp-CE complex catalyzes the first two steps of capping, and its analysis by mass spectrometry, cryo-electron microscopy, and protein crosslinking revealed the molecular basis for transcription-coupled pre-mRNA capping. CE docks to the Pol II wall and spans the end of the RNA exit tunnel to position the CE active sites for sequential binding of the exiting RNA 5' end. Thus, the RNA 5' end triggers its own capping when it emerges from Pol II, to ensure seamless RNA protection from 5'-exonucleases during early transcription.
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11
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Pearson E, Moore C. The evolutionarily conserved Pol II flap loop contributes to proper transcription termination on short yeast genes. Cell Rep 2014; 9:821-8. [PMID: 25437538 DOI: 10.1016/j.celrep.2014.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 09/18/2014] [Accepted: 10/01/2014] [Indexed: 01/19/2023] Open
Abstract
Current models of transcription termination factor recruitment to the RNA polymerase II (Pol II) transcription complex rely exclusively on the direct interaction between the termination factor and phosphorylated isoforms of the Pol II C-terminal domain (CTD). Here, we report that the Pol II flap loop is needed for physical interaction of Pol II with the Pcf11/Clp1 subcomplex of cleavage factor IA (CF IA), which functions in both 3? end processing and Pol II termination, and for proper termination of short RNAs in vitro and in vivo. Deletion of the flap loop reduces the in vivo interaction of Pol II with CF IA but increases the association of Nrd1 during stages of the transcription cycle when the CTD is predominantly Ser5 phosphorylated. We propose a model in which the flap loop coordinates a binding equilibrium between the competing termination factors Pcf11 and Nrd1 to Pol II during termination of short RNA synthesis.
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Affiliation(s)
- Erika Pearson
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Claire Moore
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA.
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12
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García-López MC, Navarro F. RNA polymerase II conserved protein domains as platforms for protein-protein interactions. Transcription 2014; 2:193-197. [PMID: 21922063 DOI: 10.4161/trns.2.4.16786] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 06/06/2011] [Accepted: 06/06/2011] [Indexed: 12/15/2022] Open
Abstract
RNA polymerase II establishes many protein-protein interactions with transcriptional regulators to coordinate gene expression, but little is known about protein domains involved in the contact with them. We use a new approach to look for conserved regions of the RNA pol II of S. cerevisiae located at the surface of the structure of the complex, hypothesizing that they might be involved in the interaction with transcriptional regulators. We defined five different conserved domains and demonstrate that all of them make contact with transcriptional regulators.
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Affiliation(s)
- M Carmen García-López
- Departamento de Biología Experimental; Facultad de Ciencias Experimentales; Universidad de Jaén; Jaén, Spain
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13
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Bentley DL. Coupling mRNA processing with transcription in time and space. Nat Rev Genet 2014; 15:163-75. [PMID: 24514444 DOI: 10.1038/nrg3662] [Citation(s) in RCA: 546] [Impact Index Per Article: 54.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Maturation of mRNA precursors often occurs simultaneously with their synthesis by RNA polymerase II (Pol II). The co-transcriptional nature of mRNA processing has permitted the evolution of coupling mechanisms that coordinate transcription with mRNA capping, splicing, editing and 3' end formation. Recent experiments using sophisticated new methods for analysis of nascent RNA have provided important insights into the relative amount of co-transcriptional and post-transcriptional processing, the relationship between mRNA elongation and processing, and the role of the Pol II carboxy-terminal domain (CTD) in regulating these processes.
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Affiliation(s)
- David L Bentley
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, MS8101, PO BOX 6511, Aurora, Colorado 80045, USA
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14
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Cross-talk of phosphorylation and prolyl isomerization of the C-terminal domain of RNA Polymerase II. Molecules 2014; 19:1481-511. [PMID: 24473209 PMCID: PMC4350670 DOI: 10.3390/molecules19021481] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 01/06/2014] [Accepted: 01/21/2014] [Indexed: 12/04/2022] Open
Abstract
Post-translational modifications of the heptad repeat sequences in the C-terminal domain (CTD) of RNA polymerase II (Pol II) are well recognized for their roles in coordinating transcription with other nuclear processes that impinge upon transcription by the Pol II machinery; and this is primarily achieved through CTD interactions with the various nuclear factors. The identification of novel modifications on new regulatory sites of the CTD suggests that, instead of an independent action for all modifications on CTD, a combinatorial effect is in operation. In this review we focus on two well-characterized modifications of the CTD, namely serine phosphorylation and prolyl isomerization, and discuss the complex interplay between the enzymes modifying their respective regulatory sites. We summarize the current understanding of how the prolyl isomerization state of the CTD dictates the specificity of writers (CTD kinases), erasers (CTD phosphatases) and readers (CTD binding proteins) and how that correlates to transcription status. Subtle changes in prolyl isomerization states cannot be detected at the primary sequence level, we describe the methods that have been utilized to investigate this mode of regulation. Finally, a general model of how prolyl isomerization regulates the phosphorylation state of CTD, and therefore transcription-coupled processes, is proposed.
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15
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Putting an 'End' to HIV mRNAs: capping and polyadenylation as potential therapeutic targets. AIDS Res Ther 2013; 10:31. [PMID: 24330569 PMCID: PMC3874655 DOI: 10.1186/1742-6405-10-31] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/26/2013] [Indexed: 01/27/2023] Open
Abstract
Like most cellular mRNAs, the 5′ end of HIV mRNAs is capped and the 3′ end matured by the process of polyadenylation. There are, however, several rather unique and interesting aspects of these post-transcriptional processes on HIV transcripts. Capping of the highly structured 5′ end of HIV mRNAs is influenced by the viral TAT protein and a population of HIV mRNAs contains a trimethyl-G cap reminiscent of U snRNAs involved in splicing. HIV polyadenylation involves active repression of a promoter-proximal polyadenylation signal, auxiliary upstream regulatory elements and moonlighting polyadenylation factors that have additional impacts on HIV biology outside of the constraints of classical mRNA 3’ end formation. This review describes these post-transcriptional novelties of HIV gene expression as well as their implications in viral biology and as possible targets for therapeutic intervention.
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16
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Affiliation(s)
- Jiannan Guo
- Biochemistry Department, University of Iowa , Iowa City, Iowa 52242, United States
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17
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Suh H, Hazelbaker DZ, Soares LM, Buratowski S. The C-terminal domain of Rpb1 functions on other RNA polymerase II subunits. Mol Cell 2013; 51:850-8. [PMID: 24035501 DOI: 10.1016/j.molcel.2013.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 07/09/2013] [Accepted: 08/02/2013] [Indexed: 10/26/2022]
Abstract
The C-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II (RNApII), coordinates recruitment of RNA- and chromatin-modifying factors to transcription complexes. It is unclear whether the CTD communicates with the catalytic core region of Rpb1 and thus must be physically connected, or instead can function as an independent domain. To address this question, CTD was transferred to other RNApII subunits. Fusions to Rpb4 or Rpb6, two RNApII subunits located near the original position of CTD, support viability in a strain carrying a truncated Rpb1. In contrast, CTD fusion to Rpb9 on the other side of RNApII does not. Rpb4-CTD and Rpb6-CTD proteins are functional for phosphorylation and recruitment of various factors, albeit with some restrictions and minor defects. Normal CTD functions are not transferred to RNApI or RNApIII by Rbp6-CTD. These results show that, with some spatial constraints, CTD can function even when disconnected from Rpb1.
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Affiliation(s)
- Hyunsuk Suh
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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18
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Aristizabal MJ, Negri GL, Benschop JJ, Holstege FCP, Krogan NJ, Kobor MS. High-throughput genetic and gene expression analysis of the RNAPII-CTD reveals unexpected connections to SRB10/CDK8. PLoS Genet 2013; 9:e1003758. [PMID: 24009531 PMCID: PMC3757075 DOI: 10.1371/journal.pgen.1003758] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 07/15/2013] [Indexed: 12/21/2022] Open
Abstract
The C-terminal domain (CTD) of RNA polymerase II (RNAPII) is composed of heptapeptide repeats, which play a key regulatory role in gene expression. Using genetic interaction, chromatin immunoprecipitation followed by microarrays (ChIP-on-chip) and mRNA expression analysis, we found that truncating the CTD resulted in distinct changes to cellular function. Truncating the CTD altered RNAPII occupancy, leading to not only decreases, but also increases in mRNA levels. The latter were largely mediated by promoter elements and in part were linked to the transcription factor Rpn4. The mediator subunit Cdk8 was enriched at promoters of these genes, and its removal not only restored normal mRNA and RNAPII occupancy levels, but also reduced the abnormally high cellular amounts of Rpn4. This suggested a positive role of Cdk8 in relationship to RNAPII, which contrasted with the observed negative role at the activated INO1 gene. Here, loss of CDK8 suppressed the reduced mRNA expression and RNAPII occupancy levels of CTD truncation mutants.
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Affiliation(s)
- Maria J. Aristizabal
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gian Luca Negri
- School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Joris J. Benschop
- Molecular Cancer Research, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Frank C. P. Holstege
- Molecular Cancer Research, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Nevan J. Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, California, United States of America
| | - Michael S. Kobor
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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19
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Affiliation(s)
- Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich and Center for Integrated Protein Science Munich (CIPSM), Marchioninistrasse 25, 81377 Munich,
Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research, Group Physical Biochemistry,
Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
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20
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Correct assembly of RNA polymerase II depends on the foot domain and is required for multiple steps of transcription in Saccharomyces cerevisiae. Mol Cell Biol 2013; 33:3611-26. [PMID: 23836886 DOI: 10.1128/mcb.00262-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Recent papers have provided insight into the cytoplasmic assembly of RNA polymerase II (RNA pol II) and its transport to the nucleus. However, little is known about the mechanisms governing its nuclear assembly, stability, degradation, and recycling. We demonstrate that the foot of RNA pol II is crucial for the assembly and stability of the complex, by ensuring the correct association of Rpb1 with Rpb6 and of the dimer Rpb4-Rpb7 (Rpb4/7). Mutations at the foot affect the assembly and stability of the enzyme, a defect that is offset by RPB6 overexpression, in coordination with Rpb1 degradation by an Asr1-independent mechanism. Correct assembly is a prerequisite for the proper maintenance of several transcription steps. In fact, assembly defects alter transcriptional activity and the amount of enzyme associated with the genes, affect C-terminal domain (CTD) phosphorylation, interfere with the mRNA-capping machinery, and possibly increase the amount of stalled RNA pol II. In addition, our data show that TATA-binding protein (TBP) occupancy does not correlate with RNA pol II occupancy or transcriptional activity, suggesting a functional relationship between assembly, Mediator, and preinitiation complex (PIC) stability. Finally, our data help clarify the mechanisms governing the assembly and stability of RNA pol II.
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Hsin JP, Manley JL. The RNA polymerase II CTD coordinates transcription and RNA processing. Genes Dev 2012; 26:2119-37. [PMID: 23028141 DOI: 10.1101/gad.200303.112] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The C-terminal domain (CTD) of the RNA polymerase II largest subunit consists of multiple heptad repeats (consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), varying in number from 26 in yeast to 52 in vertebrates. The CTD functions to help couple transcription and processing of the nascent RNA and also plays roles in transcription elongation and termination. The CTD is subject to extensive post-translational modification, most notably phosphorylation, during the transcription cycle, which modulates its activities in the above processes. Therefore, understanding the nature of CTD modifications, including how they function and how they are regulated, is essential to understanding the mechanisms that control gene expression. While the significance of phosphorylation of Ser2 and Ser5 residues has been studied and appreciated for some time, several additional modifications have more recently been added to the CTD repertoire, and insight into their function has begun to emerge. Here, we review findings regarding modification and function of the CTD, highlighting the important role this unique domain plays in coordinating gene activity.
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Affiliation(s)
- Jing-Ping Hsin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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22
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Hartzog GA, Fu J. The Spt4-Spt5 complex: a multi-faceted regulator of transcription elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:105-15. [PMID: 22982195 DOI: 10.1016/j.bbagrm.2012.08.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/21/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
Abstract
In all domains of life, elongating RNA polymerases require the assistance of accessory factors to maintain their processivity and regulate their rate. Among these elongation factors, the Spt5/NusG factors stand out. Members of this protein family appear to be the only transcription accessory proteins that are universally conserved across all domains of life. In archaea and eukaryotes, Spt5 associates with a second protein, Spt4. In addition to regulating elongation, the eukaryotic Spt4-Spt5 complex appears to couple chromatin modification states and RNA processing to transcription elongation. This review discusses the experimental bases for our current understanding of Spt4-Spt5 function and recent studies that are beginning to elucidate the structure of Spt4-Spt5/RNA polymerase complexes and mechanism of Spt4-Spt5 action. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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Affiliation(s)
- Grant A Hartzog
- Department of MCD Biology, University of California, Santa Cruz, CA 95064, USA.
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23
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Regulation of mammalian transcription by Gdown1 through a novel steric crosstalk revealed by cryo-EM. EMBO J 2012; 31:3575-87. [PMID: 22850672 DOI: 10.1038/emboj.2012.205] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 07/03/2012] [Indexed: 01/24/2023] Open
Abstract
In mammals, a distinct RNA polymerase II form, RNAPII(G) contains a novel subunit Gdown1 (encoded by POLR2M), which represses gene activation, only to be reversed by the multisubunit Mediator co-activator. Here, we employed single-particle cryo-electron microscopy (cryo-EM) to disclose the architectures of RNAPII(G), RNAPII and RNAPII in complex with the transcription initiation factor TFIIF, all to ~19 Å. Difference analysis mapped Gdown1 mostly to the RNAPII Rpb5 shelf-Rpb1 jaw, supported by antibody labelling experiments. These structural features correlate with the moderate increase in the efficiency of RNA chain elongation by RNAP II(G). In addition, our updated RNAPII-TFIIF map showed that TFIIF tethers multiple regions surrounding the DNA-binding cleft, in agreement with cross-linking and biochemical mapping. Gdown1's binding sites overlap extensively with those of TFIIF, with Gdown1 sterically excluding TFIIF from RNAPII, herein demonstrated by competition assays using size exclusion chromatography. In summary, our work establishes a structural basis for Gdown1 impeding initiation at promoters, by obstruction of TFIIF, accounting for an additional dependent role of Mediator in activated transcription.
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Amino Acid Substitutions in the Caenorhabditis elegans RNA Polymerase II Large Subunit AMA-1/RPB-1 that Result in α-Amanitin Resistance and/or Reduced Function. G3-GENES GENOMES GENETICS 2011; 1:411-6. [PMID: 22384351 PMCID: PMC3276164 DOI: 10.1534/g3.111.000968] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 08/31/2011] [Indexed: 11/18/2022]
Abstract
Mutations in the Caenorhabditis elegans RNA polymerase II AMA-1/RPB-1 subunit that cause α-amanitin resistance and/or developmental defects were isolated previously. We identified 12 of these mutations and mapped them onto the Saccharomyces cerevisiae RPB1 structure to provide insight into AMA-1 regions that are essential for development in a multicellular organism.
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The conserved foot domain of RNA pol II associates with proteins involved in transcriptional initiation and/or early elongation. Genetics 2011; 189:1235-48. [PMID: 21954159 DOI: 10.1534/genetics.111.133215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
RNA polymerase (pol) II establishes many protein-protein interactions with transcriptional regulators to coordinate different steps of transcription. Although some of these interactions have been well described, little is known about the existence of RNA pol II regions involved in contact with transcriptional regulators. We hypothesize that conserved regions on the surface of RNA pol II contact transcriptional regulators. We identified such an RNA pol II conserved region that includes the majority of the "foot" domain and identified interactions of this region with Mvp1, a protein required for sorting proteins to the vacuole, and Spo14, a phospholipase D. Deletion of MVP1 and SPO14 affects the transcription of their target genes and increases phosphorylation of Ser5 in the carboxy-terminal domain (CTD). Genetic, phenotypic, and functional analyses point to a role for these proteins in transcriptional initiation and/or early elongation, consistent with their genetic interactions with CEG1, a guanylyltransferase subunit of the Saccharomyces cerevisiae capping enzyme.
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Martinez-Rucobo FW, Sainsbury S, Cheung ACM, Cramer P. Architecture of the RNA polymerase-Spt4/5 complex and basis of universal transcription processivity. EMBO J 2011; 30:1302-10. [PMID: 21386817 PMCID: PMC3094117 DOI: 10.1038/emboj.2011.64] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 02/17/2011] [Indexed: 01/24/2023] Open
Abstract
Spt5 and NusG play a conserved role in stimulating RNA polymerase II transcription elongation and processivity. Here, the crystal structure of Spt4/5 bound to the RNA polymerase clamp domain reveals that the factor binds above DNA and RNA in the active centre cleft preventing premature dissociation of the polymerase. Related RNA polymerases (RNAPs) carry out cellular gene transcription in all three kingdoms of life. The universal conservation of the transcription machinery extends to a single RNAP-associated factor, Spt5 (or NusG in bacteria), which renders RNAP processive and may have arisen early to permit evolution of long genes. Spt5 associates with Spt4 to form the Spt4/5 heterodimer. Here, we present the crystal structure of archaeal Spt4/5 bound to the RNAP clamp domain, which forms one side of the RNAP active centre cleft. The structure revealed a conserved Spt5–RNAP interface and enabled modelling of complexes of Spt4/5 counterparts with RNAPs from all kingdoms of life, and of the complete yeast RNAP II elongation complex with bound Spt4/5. The N-terminal NGN domain of Spt5/NusG closes the RNAP active centre cleft to lock nucleic acids and render the elongation complex stable and processive. The C-terminal KOW1 domain is mobile, but its location is restricted to a region between the RNAP clamp and wall above the RNA exit tunnel, where it may interact with RNA and/or other factors.
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Affiliation(s)
- Fuensanta W Martinez-Rucobo
- Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munich, Germany
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