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Gillis A, Berry S. Global control of RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195024. [PMID: 38552781 DOI: 10.1016/j.bbagrm.2024.195024] [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: 12/19/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024]
Abstract
RNA polymerase II (Pol II) is the multi-protein complex responsible for transcribing all protein-coding messenger RNA (mRNA). Most research on gene regulation is focused on the mechanisms controlling which genes are transcribed when, or on the mechanics of transcription. How global Pol II activity is determined receives comparatively less attention. Here, we follow the life of a Pol II molecule from 'assembly of the complex' to nuclear import, enzymatic activity, and degradation. We focus on how Pol II spends its time in the nucleus, and on the two-way relationship between Pol II abundance and activity in the context of homeostasis and global transcriptional changes.
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Affiliation(s)
- Alexander Gillis
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia; UNSW RNA Institute, University of New South Wales, Sydney, Australia; Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Scott Berry
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia; UNSW RNA Institute, University of New South Wales, Sydney, Australia; Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
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2
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Feng Z, Liu S, Su M, Song C, Lin C, Zhao F, Li Y, Zeng X, Zhu Y, Hou Y, Ren C, Zhang H, Yi P, Ji Y, Wang C, Li H, Ma M, Luo L, Li L. TANGO6 regulates cell proliferation via COPI vesicle-mediated RPB2 nuclear entry. Nat Commun 2024; 15:2371. [PMID: 38490996 PMCID: PMC10943085 DOI: 10.1038/s41467-024-46720-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 03/01/2024] [Indexed: 03/18/2024] Open
Abstract
Coat protein complex I (COPI) vesicles mediate the retrograde transfer of cargo between Golgi cisternae and from the Golgi to the endoplasmic reticulum (ER). However, their roles in the cell cycle and proliferation are unclear. This study shows that TANGO6 associates with COPI vesicles via two transmembrane domains. The TANGO6 N- and C-terminal cytoplasmic fragments capture RNA polymerase II subunit B (RPB) 2 in the cis-Golgi during the G1 phase. COPI-docked TANGO6 carries RPB2 to the ER and then to the nucleus. Functional disruption of TANGO6 hinders the nuclear entry of RPB2, which accumulates in the cytoplasm, causing cell cycle arrest in the G1 phase. The conditional depletion or overexpression of TANGO6 in mouse hematopoietic stem cells results in compromised or expanded hematopoiesis. Our study results demonstrate that COPI vesicle-associated TANGO6 plays a role in the regulation of cell cycle progression by directing the nuclear transfer of RPB2, making it a potential target for promoting or arresting cell expansion.
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Affiliation(s)
- Zhi Feng
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China
| | - Shengnan Liu
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Ming Su
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China
| | - Chunyu Song
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Chenyu Lin
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Fangying Zhao
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Yang Li
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China
| | - Xianyan Zeng
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Yong Zhu
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Yu Hou
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Chunguang Ren
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Huan Zhang
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Ping Yi
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Chongqing Medical University, Chongqing, 401120, PR China
| | - Yong Ji
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine; Key Laboratory of Targeted Intervention of Cardiovascular Disease; Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, 211166, PR China
- National Key Laboratory of Frigid Zone Cardiovascular Diseases (NKLFZCD), Harbin Medical University, Harbin, 150076, Heilongjiang, PR China
| | - Chao Wang
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, PR China
| | - Hongtao Li
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Ming Ma
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Lingfei Luo
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China.
| | - Li Li
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China.
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3
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Tessier TM, King CR, Mymryk JS. Exploiting the endogenous yeast nuclear proteome to identify short linear motifs in vivo. CELL REPORTS METHODS 2023; 3:100637. [PMID: 37949066 PMCID: PMC10694487 DOI: 10.1016/j.crmeth.2023.100637] [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: 05/17/2023] [Revised: 09/01/2023] [Accepted: 10/17/2023] [Indexed: 11/12/2023]
Abstract
Peptide-domain interactions mediated by short linear motifs (SLiMs) play crucial roles in cellular biology. The simplicity of SLiMs poses challenges in their computational identification. Existing high-throughput methods for discovering SLiMs lack cellular context as they are typically performed in vitro. We developed a functional selection method using yeast to identify peptides that interact with the endogenous yeast nuclear proteome. Remarkably, peptides selected for in yeast also mediated nuclear import in human cells. Notably, the identified peptides did not resemble classical nuclear localization sequences. This platform has the potential to identify and investigate motifs that interact with the nuclear proteome of yeast and human and to aid in the identification and understanding of alternative protein nuclear import mechanisms.
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Affiliation(s)
- Tanner M Tessier
- Department of Microbiology and Immunology, Western University, London, ON, Canada
| | - Cason R King
- Department of Microbiology and Immunology, Western University, London, ON, Canada
| | - Joe S Mymryk
- Department of Microbiology and Immunology, Western University, London, ON, Canada; Department of Oncology, Western University, London, ON, Canada; Department of Otolaryngology, Western University, London, ON, Canada; London Regional Cancer Program, Lawson Health Research Institute, London, ON, Canada.
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4
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Nagy-Mikó B, Németh-Szatmári O, Faragó-Mészáros R, Csókási A, Bognár B, Ördög N, Borsos BN, Majoros H, Ujfaludi Z, Oláh-Németh O, Nikolényi A, Dobi Á, Kószó R, Sántha D, Lázár G, Simonka Z, Paszt A, Ormándi K, Pankotai T, Boros IM, Villányi Z, Vörös A. Predictive Potential of RNA Polymerase B (II) Subunit 1 (RPB1) Cytoplasmic Aggregation for Neoadjuvant Chemotherapy Failure. Int J Mol Sci 2023; 24:15869. [PMID: 37958852 PMCID: PMC10650411 DOI: 10.3390/ijms242115869] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023] Open
Abstract
We aimed to investigate the contribution of co-translational protein aggregation to the chemotherapy resistance of tumor cells. Increased co-translational protein aggregation reflects altered translation regulation that may have the potential to buffer transcription under genotoxic stress. As an indicator for such an event, we followed the cytoplasmic aggregation of RPB1, the aggregation-prone largest subunit of RNA polymerase II, in biopsy samples taken from patients with invasive carcinoma of no special type. RPB1 frequently aggregates co-translationally in the absence of proper HSP90 chaperone function or in ribosome mutant cells as revealed formerly in yeast. We found that cytoplasmic foci of RPB1 occur in larger sizes in tumors that showed no regression after therapy. Based on these results, we propose that monitoring the cytoplasmic aggregation of RPB1 may be suitable for determining-from biopsy samples taken before treatment-the effectiveness of neoadjuvant chemotherapy.
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Affiliation(s)
- Bence Nagy-Mikó
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
| | - Orsolya Németh-Szatmári
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
| | - Réka Faragó-Mészáros
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
| | - Aliz Csókási
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
| | - Bence Bognár
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
| | - Nóra Ördög
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
| | - Barbara N. Borsos
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
| | - Hajnalka Majoros
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
- Competence Centre of the Life Sciences Cluster of the Centre of Excellence for Interdisciplinary Research, Development and Innovation, University of Szeged, Dugonics tér 13, H-6720 Szeged, Hungary
| | - Zsuzsanna Ujfaludi
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
- Competence Centre of the Life Sciences Cluster of the Centre of Excellence for Interdisciplinary Research, Development and Innovation, University of Szeged, Dugonics tér 13, H-6720 Szeged, Hungary
| | - Orsolya Oláh-Németh
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
| | - Aliz Nikolényi
- Department of Oncotherapy, Albert Szent-Györgyi Health Centre, University of Szeged, 12 Korányi Fasor, H-6720 Szeged, Hungary
| | - Ágnes Dobi
- Department of Oncotherapy, Albert Szent-Györgyi Health Centre, University of Szeged, 12 Korányi Fasor, H-6720 Szeged, Hungary
| | - Renáta Kószó
- Department of Oncotherapy, Albert Szent-Györgyi Health Centre, University of Szeged, 12 Korányi Fasor, H-6720 Szeged, Hungary
| | - Dóra Sántha
- Department of Oncotherapy, Albert Szent-Györgyi Health Centre, University of Szeged, 12 Korányi Fasor, H-6720 Szeged, Hungary
| | - György Lázár
- Department of Surgery, Albert Szent-Györgyi Health Centre, University of Szeged, 8 Semmelweis Street, H-6725 Szeged, Hungary
| | - Zsolt Simonka
- Department of Surgery, Albert Szent-Györgyi Health Centre, University of Szeged, 8 Semmelweis Street, H-6725 Szeged, Hungary
| | - Attila Paszt
- Department of Surgery, Albert Szent-Györgyi Health Centre, University of Szeged, 8 Semmelweis Street, H-6725 Szeged, Hungary
| | - Katalin Ormándi
- Department of Radiology, Albert Szent-Györgyi Health Centre, University of Szeged, 6 Semmelweis Street, H-6725 Szeged, Hungary
| | - Tibor Pankotai
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
- Competence Centre of the Life Sciences Cluster of the Centre of Excellence for Interdisciplinary Research, Development and Innovation, University of Szeged, Dugonics tér 13, H-6720 Szeged, Hungary
- Genome Integrity and DNA Repair Core Group, Hungarian Centre of Excellence for Molecular Medicine (HCEMM), University of Szeged, Budapesti út 9, H-6728 Szeged, Hungary
| | - Imre M. Boros
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
| | - Zoltán Villányi
- Department of Biochemistry and Molecular Biology, University of Szeged, 52 Középfasor, H-6726 Szeged, Hungary
| | - András Vörös
- Department of Pathology, Albert Szent-Györgyi Medical School, University of Szeged, Állomás utca 1, H-6725 Szeged, Hungary
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5
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Tian K, Wang R, Huang J, Wang H, Ji X. Subcellular localization shapes the fate of RNA polymerase III. Cell Rep 2023; 42:112941. [PMID: 37556328 DOI: 10.1016/j.celrep.2023.112941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 08/11/2023] Open
Abstract
RNA polymerase III (Pol III) plays a vital role in transcription and as a viral-DNA sensor, but how it is assembled and distributed within cells remains poorly understood. Here, we show that Pol III is assembled with chaperones in the cytoplasm and forms transcription-dependent protein clusters upon transport into the nucleus. The largest subunit (RPC1) depletion through an auxin-inducible degron leads to rapid degradation and disassembly of Pol III complex in the nucleus and cytoplasm, respectively. This generates a pool of partially assembled Pol III intermediates, which can be rapidly mobilized into the nucleus upon the restoration of RPC1. Our study highlights the critical role of subcellular localization in determining Pol III's fate and provides insight into the dynamic regulation of nuclear Pol III levels and the origin of cytoplasmic Pol III complexes involved in mediating viral immunity.
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Affiliation(s)
- Kai Tian
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Rui Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Jie Huang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Hui Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Xiong Ji
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
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6
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Garrido-Godino AI, Martín-Expósito M, Gutiérrez-Santiago F, Perez-Fernandez J, Navarro F. Rpb4/7, a key element of RNA pol II to coordinate mRNA synthesis in the nucleus with cytoplasmic functions in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2022; 1865:194846. [PMID: 35905859 DOI: 10.1016/j.bbagrm.2022.194846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 07/11/2022] [Accepted: 07/17/2022] [Indexed: 06/15/2023]
Affiliation(s)
- A I Garrido-Godino
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain
| | - M Martín-Expósito
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain
| | - F Gutiérrez-Santiago
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain
| | - J Perez-Fernandez
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain.
| | - F Navarro
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; Instituto Universitario de Investigación en Olivar y Aceites de Oliva, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain.
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7
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Synthetic negative genome screen of the GPN-loop GTPase NPA3 in Saccharomyces cerevisiae. Curr Genet 2022; 68:343-360. [PMID: 35660944 DOI: 10.1007/s00294-022-01243-1] [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: 12/27/2021] [Revised: 04/21/2022] [Accepted: 04/30/2022] [Indexed: 11/03/2022]
Abstract
The GPN-loop GTPase Npa3 is encoded by an essential gene in the yeast Saccharomyces cerevisiae. Npa3 plays a critical role in the assembly and nuclear accumulation of RNA polymerase II (RNAPII), a function that may explain its essentiality. Genetic interactions describe the extent to which a mutation in a particular gene affects a specific phenotype when co-occurring with an alteration in a second gene. Discovering synthetic negative genetic interactions has long been used as a tool to delineate the functional relatedness between pairs of genes participating in common or compensatory biological pathways. Previously, our group showed that nuclear targeting and transcriptional activity of RNAPII were unaffected in cells expressing exclusively a C-terminal truncated mutant version of Npa3 (npa3∆C) lacking the last 106 residues naturally absent from the single GPN protein in Archaea, but universally conserved in all Npa3 orthologs of eukaryotes. To gain insight into novel cellular functions for Npa3, we performed here a genome-wide Synthetic Genetic Array (SGA) study coupled to bulk fluorescence monitoring to identify negative genetic interactions of NPA3 by crossing an npa3∆C strain with a 4,389 nonessential gene-deletion collection. This genetic screen revealed previously unknown synthetic negative interactions between NPA3 and 15 genes. Our results revealed that the Npa3 C-terminal tail extension regulates the participation of this essential GTPase in previously unknown biological processes related to mitochondrial homeostasis and ribosome biogenesis.
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Garrido-Godino AI, Cuevas-Bermúdez A, Gutiérrez-Santiago F, Mota-Trujillo MDC, Navarro F. The Association of Rpb4 with RNA Polymerase II Depends on CTD Ser5P Phosphatase Rtr1 and Influences mRNA Decay in Saccharomyces cerevisiae. Int J Mol Sci 2022; 23:2002. [PMID: 35216121 PMCID: PMC8875030 DOI: 10.3390/ijms23042002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 02/04/2023] Open
Abstract
Rtr1 is an RNA polymerase II (RNA pol II) CTD-phosphatase that influences gene expression during the transition from transcription initiation to elongation and during transcription termination. Rtr1 interacts with the RNA pol II and this interaction depends on the phosphorylation state of the CTD of Rpb1, which may influence dissociation of the heterodimer Rpb4/7 during transcription. In addition, Rtr1 was proposed as an RNA pol II import factor in RNA pol II biogenesis and participates in mRNA decay by autoregulating the turnover of its own mRNA. Our work shows that Rtr1 acts in RNA pol II assembly by mediating the Rpb4/7 association with the rest of the enzyme. RTR1 deletion alters RNA pol II assembly and increases the amount of RNA pol II associated with the chromatin that lacks Rpb4, decreasing Rpb4-mRNA imprinting and, consequently, increasing mRNA stability. Thus, Rtr1 interplays RNA pol II biogenesis and mRNA decay regulation. Our data also indicate that Rtr1 mediates mRNA decay regulation more broadly than previously proposed by cooperating with Rpb4. Interestingly, our data include new layers in the mechanisms of gene regulation and in the crosstalk between mRNA synthesis and decay by demonstrating how the association of Rpb4/7 to the RNA pol II influences mRNA decay.
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Affiliation(s)
- Ana I. Garrido-Godino
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Abel Cuevas-Bermúdez
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Francisco Gutiérrez-Santiago
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Maria del Carmen Mota-Trujillo
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Francisco Navarro
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
- Centro de Estudios Avanzados en Aceite de Oliva y Olivar, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain
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9
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Wing CE, Fung HYJ, Chook YM. Karyopherin-mediated nucleocytoplasmic transport. Nat Rev Mol Cell Biol 2022; 23:307-328. [PMID: 35058649 PMCID: PMC10101760 DOI: 10.1038/s41580-021-00446-7] [Citation(s) in RCA: 107] [Impact Index Per Article: 53.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2021] [Indexed: 12/25/2022]
Abstract
Efficient and regulated nucleocytoplasmic trafficking of macromolecules to the correct subcellular compartment is critical for proper functions of the eukaryotic cell. The majority of the macromolecular traffic across the nuclear pores is mediated by the Karyopherin-β (or Kap) family of nuclear transport receptors. Work over more than two decades has shed considerable light on how the different Kap family members bring their respective cargoes into the nucleus or the cytoplasm in efficient and highly regulated manners. In this Review, we overview the main features and established functions of Kap family members, describe how Kaps recognize their cargoes and discuss the different ways in which these Kap-cargo interactions can be regulated, highlighting new findings and open questions. We also describe current knowledge of the import and export of the components of three large gene expression machines - the core replisome, RNA polymerase II and the ribosome - pointing out the questions that persist about how such large macromolecular complexes are trafficked to serve their function in a designated subcellular location.
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Zhang Z, Li H, Deng Y, Schuck K, Raulefs S, Maeritz N, Yu Y, Hechler T, Pahl A, Fernández-Sáiz V, Wan Y, Wang G, Engleitner T, Öllinger R, Rad R, Reichert M, Diakopoulos KN, Weber V, Li J, Shen S, Zou X, Kleeff J, Mihaljevic A, Michalski CW, Algül H, Friess H, Kong B. AGR2-Dependent Nuclear Import of RNA Polymerase II Constitutes a Specific Target of Pancreatic Ductal Adenocarcinoma in the Context of Wild-Type p53. Gastroenterology 2021; 161:1601-1614.e23. [PMID: 34303658 DOI: 10.1053/j.gastro.2021.07.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 06/25/2021] [Accepted: 07/17/2021] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Promoted by pancreatitis, oncogenic KrasG12D triggers acinar cells' neoplastic transformation through acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasia. Anterior gradient 2 (Agr2), a known inhibitor of p53, is detected at early stage of pancreatic ductal adenocarcinoma (PDAC) development. RNA polymerase II (RNAPII) is a key nuclear enzyme; regulation of its nuclear localization in mammalian cells represents a potential therapeutic target. METHODS A mouse model of inflammation-accelerated KrasG12D-driven ADM and pancreatic intraepithelial neoplasia development was used. Pancreas-specific Agr2 ablation was performed to access its role in pancreatic carcinogenesis. Hydrophobic hexapeptides loaded in liposomes were developed to disrupt Agr2-RNAPII complex. RESULTS We found that Agr2 is up-regulated in ADM-to-pancreatic intraepithelial neoplasia transition in inflammation and KrasG12D-driven early pancreatic carcinogenesis. Genetic ablation of Agr2 specifically blocks this metaplastic-to-neoplastic process. Mechanistically, Agr2 directs the nuclear import of RNAPII via its C-terminal nuclear localization signal, undermining the ATR-dependent p53 activation in ADM lesions. Because Agr2 binds to the largest subunit of RNAPII in a peptide motif-dependent manner, we developed a hexapeptide to interfere with the nuclear import of RNAPII by competitively disrupting the Agr2-RNAPII complex. This novel hexapeptide leads to dysfunction of RNAPII with concomitant activation of DNA damage response in early neoplastic lesions; hence, it dramatically compromises PDAC initiation in vivo. Moreover, the hexapeptide sensitizes PDAC cells and patient-derived organoids harboring wild-type p53 to RNAPII inhibitors and first-line chemotherapeutic agents in vivo. Of note, this therapeutic effect is efficient across various cancer types. CONCLUSIONS Agr2 is identified as a novel adaptor protein for nuclear import of RNAPII in mammalian cells. Also, we provide genetic evidence defining Agr2-dependent nuclear import of RNAPII as a pharmaceutically accessible target for prevention and treatment in PDAC in the context of wild-type p53.
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MESH Headings
- Active Transport, Cell Nucleus
- Animals
- Antineoplastic Agents/pharmacology
- Carcinoma in Situ/drug therapy
- Carcinoma in Situ/enzymology
- Carcinoma in Situ/genetics
- Carcinoma in Situ/pathology
- Carcinoma, Pancreatic Ductal/drug therapy
- Carcinoma, Pancreatic Ductal/enzymology
- Carcinoma, Pancreatic Ductal/genetics
- Carcinoma, Pancreatic Ductal/pathology
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Gene Expression Regulation, Neoplastic
- Metaplasia
- Mice, Inbred C57BL
- Mice, Inbred NOD
- Mice, Knockout
- Mice, SCID
- Mucoproteins/genetics
- Mucoproteins/metabolism
- Mutation
- Oligopeptides/pharmacology
- Oncogene Proteins/genetics
- Oncogene Proteins/metabolism
- Pancreatic Neoplasms/drug therapy
- Pancreatic Neoplasms/enzymology
- Pancreatic Neoplasms/genetics
- Pancreatic Neoplasms/pathology
- Proto-Oncogene Proteins p21(ras)/genetics
- RNA Polymerase II/genetics
- RNA Polymerase II/metabolism
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Mice
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Affiliation(s)
- Zhiheng Zhang
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Hongzhen Li
- Department of Gastroenterology, the Affiliated Drum Tower Hospital of Nanjing University, Medical School, Nanjing, China; Department of Surgery, Ulm University Hospital, Ulm University, Ulm, Germany
| | - Yibin Deng
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, and College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Kathleen Schuck
- Department of Surgery, Ulm University Hospital, Ulm University, Ulm, Germany
| | - Susanne Raulefs
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Nadja Maeritz
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Yuanyuan Yu
- Department of Surgery, Ulm University Hospital, Ulm University, Ulm, Germany
| | | | - Andreas Pahl
- Heidelberg Pharma Research GmbH, Ladenburg, Germany
| | - Vanesa Fernández-Sáiz
- Department of Medicine III, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; Center for Translational Cancer Research, Technische Universität München, Munich, Germany
| | - Yuan Wan
- The Pq Laboratory of Micro/Nano BiomeDx, Department of Biomedical Engineering, Binghamton University, State University of New York, Binghamton, New York
| | - Guosheng Wang
- The Pq Laboratory of Micro/Nano BiomeDx, Department of Biomedical Engineering, Binghamton University, State University of New York, Binghamton, New York
| | - Thomas Engleitner
- Center for Translational Cancer Research, Technische Universität München, Munich, Germany; Department of Medicine II, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; Comprehensive Cancer Center Munich, Technical University of Munich, Munich, Germany
| | - Rupert Öllinger
- Center for Translational Cancer Research, Technische Universität München, Munich, Germany; Department of Medicine II, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; German Cancer Consortium at the partner site Munich, Munich, Germany
| | - Roland Rad
- Center for Translational Cancer Research, Technische Universität München, Munich, Germany; Department of Medicine II, Klinikum rechts der Isar, Technische Universität München, Munich, Germany; German Cancer Consortium at the partner site Munich, Munich, Germany
| | - Maximilian Reichert
- Department of Medicine II, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | | | - Verena Weber
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Jingjing Li
- Department of Gastroenterology, the Affiliated Drum Tower Hospital of Nanjing University, Medical School, Nanjing, China
| | - Shanshan Shen
- Department of Gastroenterology, the Affiliated Drum Tower Hospital of Nanjing University, Medical School, Nanjing, China
| | - Xiaoping Zou
- Department of Gastroenterology, the Affiliated Drum Tower Hospital of Nanjing University, Medical School, Nanjing, China
| | - Jörg Kleeff
- Department of Visceral, Vascular and Endocrine Surgery, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Andre Mihaljevic
- Department of Surgery, Ulm University Hospital, Ulm University, Ulm, Germany
| | | | - Hana Algül
- Comprehensive Cancer Center Munich, Technical University of Munich, Munich, Germany
| | - Helmut Friess
- Department of Surgery, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Bo Kong
- Department of Gastroenterology, the Affiliated Drum Tower Hospital of Nanjing University, Medical School, Nanjing, China; Department of Surgery, Ulm University Hospital, Ulm University, Ulm, Germany.
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11
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Minaker SW, Kofoed MC, Hieter P, Stirling PC. A nuclear proteome localization screen reveals the exquisite specificity of Gpn2 in RNA polymerase biogenesis. Cell Cycle 2021; 20:1361-1373. [PMID: 34180355 DOI: 10.1080/15384101.2021.1943879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The GPN proteins are a conserved family of GTP-binding proteins that are involved in the assembly and subsequent import of RNA polymerase II and III. In this study, we sought to ascertain the specificity of yeast GPN2 for RNA polymerases by screening the localization of a collection of 1350 GFP-tagged nuclear proteins in WT or GPN2 mutant cells. We found that the strongest mislocalization occurred for RNA polymerase II and III subunits and only a handful of other RNAPII associated proteins were altered in GPN2 mutant cells. Our screen identified Ess1, an Rpb1 C-terminal domain (CTD) prolyl isomerase, as mislocalized in GPN2 mutants. Building on this observation we tested for effects of mutations in other factors which regulate Rpb1-CTD phosphorylation status. This uncovered significant changes in nuclear-cytoplasmic distribution of Rpb1-GFP in strains with disrupted RNA polymerase CTD kinases or phosphatases. Overall, this screen shows the exquisite specificity of GPN2 for RNA polymerase transport, and reveals a previously unappreciated role for CTD modification in RNAPII nuclear localization.
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Affiliation(s)
- Sean W Minaker
- Terry Fox Laboratories, BC Cancer Research Institute, Vancouver, Canada
| | - Megan C Kofoed
- Michael Smith Laboratory, University of British Columbia, Vancouver, Canada
| | - Philip Hieter
- Michael Smith Laboratory, University of British Columbia, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Peter C Stirling
- Terry Fox Laboratories, BC Cancer Research Institute, Vancouver, Canada
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12
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Fianu I, Dienemann C, Aibara S, Schilbach S, Cramer P. Cryo-EM structure of mammalian RNA polymerase II in complex with human RPAP2. Commun Biol 2021; 4:606. [PMID: 34021257 PMCID: PMC8140126 DOI: 10.1038/s42003-021-02088-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/08/2021] [Indexed: 11/09/2022] Open
Abstract
Nuclear import of RNA polymerase II (Pol II) involves the conserved factor RPAP2. Here we report the cryo-electron microscopy (cryo-EM) structure of mammalian Pol II in complex with human RPAP2 at 2.8 Å resolution. The structure shows that RPAP2 binds between the jaw domains of the polymerase subunits RPB1 and RPB5. RPAP2 is incompatible with binding of downstream DNA during transcription and is displaced upon formation of a transcription pre-initiation complex.
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Affiliation(s)
- Isaac Fianu
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christian Dienemann
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Shintaro Aibara
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Sandra Schilbach
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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13
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Garrido-Godino AI, Gutiérrez-Santiago F, Navarro F. Biogenesis of RNA Polymerases in Yeast. Front Mol Biosci 2021; 8:669300. [PMID: 34026841 PMCID: PMC8136413 DOI: 10.3389/fmolb.2021.669300] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/31/2021] [Indexed: 01/25/2023] Open
Abstract
Eukaryotic RNA polymerases (RNA pols) transcriptional processes have been extensively investigated, and the structural analysis of eukaryotic RNA pols has been explored. However, the global assembly and biogenesis of these heteromultimeric complexes have been narrowly studied. Despite nuclear transcription being carried out by three RNA polymerases in eukaryotes (five in plants) with specificity in the synthesis of different RNA types, the biogenesis process has been proposed to be similar, at least for RNA pol II, to that of bacteria, which contains only one RNA pol. The formation of three different interacting subassembly complexes to conform the complete enzyme in the cytoplasm, prior to its nuclear import, has been assumed. In Saccharomyces cerevisiae, recent studies have examined in depth the biogenesis of RNA polymerases by characterizing some elements involved in the assembly of these multisubunit complexes, some of which are conserved in humans. This study reviews the latest studies governing the mechanisms and proteins described as being involved in the biogenesis of RNA polymerases in yeast.
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Affiliation(s)
- Ana I Garrido-Godino
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Jaén, Spain
| | | | - Francisco Navarro
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Jaén, Spain.,Centro de Estudios Avanzados en Aceite de Oliva y Olivar, Universidad de Jaén, Jaén, Spain
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14
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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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15
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Saltzberg DJ, Viswanath S, Echeverria I, Chemmama IE, Webb B, Sali A. Using Integrative Modeling Platform to compute, validate, and archive a model of a protein complex structure. Protein Sci 2020; 30:250-261. [PMID: 33166013 DOI: 10.1002/pro.3995] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/06/2020] [Accepted: 11/06/2020] [Indexed: 12/18/2022]
Abstract
Biology is advanced by producing structural models of biological systems, such as protein complexes. Some systems are recalcitrant to traditional structure determination methods. In such cases, it may still be possible to produce useful models by integrative structure determination that depends on simultaneous use of multiple types of data. An ensemble of models that are sufficiently consistent with the data is produced by a structural sampling method guided by a data-dependent scoring function. The variation in the ensemble of models quantified the uncertainty of the structure, generally resulting from the uncertainty in the input information and actual structural heterogeneity in the samples used to produce the data. Here, we describe how to generate, assess, and interpret ensembles of integrative structural models using our open source Integrative Modeling Platform program (https://integrativemodeling.org).
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Affiliation(s)
- Daniel J Saltzberg
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California, San Francisco, California, USA
| | - Shruthi Viswanath
- National Center for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Ignacia Echeverria
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California, San Francisco, California, USA.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, USA
| | - Ilan E Chemmama
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California, San Francisco, California, USA
| | - Ben Webb
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California, San Francisco, California, USA
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences, University of California, San Francisco, California, USA
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16
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Bharati AP, Kumari S, Akhtar MS. Proteome analysis of Saccharomyces cerevisiae after methyl methane sulfonate (MMS) treatment. Biochem Biophys Rep 2020; 24:100820. [PMID: 33072891 PMCID: PMC7548944 DOI: 10.1016/j.bbrep.2020.100820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 09/02/2020] [Accepted: 09/03/2020] [Indexed: 11/27/2022] Open
Abstract
The treatment of methyl methane sulfonate (MMS) increases sensitivity to the DNA damage which, further leads to the cell death followed by a cell cycle delay. Delay in the cell cycle is because of the change in global transcription regulation which results into proteome change. There are several microarray studies on the transcriptome changes after MMS treatment, but very few studies are reported related to proteome change. The proteome analysis in this report identified subgroups of proteins, belonging to known cell cycle regulators, metabolic pathways and protein folding. About 53 proteins were identified by MS/MS and found that 36 of them were induced, 10 were repressed and few of them showed insignificant change. Our results indicated the change in the interactome as well as phosphorylation status of carboxy terminal domain (CTD) of RNA Polymerase II (RNAP-II) after MMS treatment. The RNAP-II complex was affinity purified and ~1640 peptides were identified using nano LC/MS corresponding to 27 interacting proteins along with the twelve RNAP-II subunit. These identified proteins participated in the repair of the damage, changes the function of the main energetic pathways and the carbon flux in various end products. The main metabolic enzymes in the glycolysis, pyruvate phosphate and amino acid biosynthesis pathways showed significant change. Our results indicate that DNA damage is somehow related to these pathways and is co-regulated simultaneously.
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Affiliation(s)
- Akhilendra Pratap Bharati
- ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Mau, Uttar Pradesh, 275103, India
- Molecular and Structural Biology Division, CSIR-CDRI, Sector 10, Jankipuram Extension, Lucknow, PIN 226 031, India
| | - Sunita Kumari
- ICAR-Indian Institute of Seed Science, Mau, Uttar Pradesh, 275103, India
| | - Md Sohail Akhtar
- Molecular and Structural Biology Division, CSIR-CDRI, Sector 10, Jankipuram Extension, Lucknow, PIN 226 031, India
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17
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Mazzola L, Oliver KL, Labalme A, Baykan B, Muona M, Joensuu TH, Courage C, Chatron N, Borsani G, Alix E, Ramond F, Touraine R, Bahlo M, Bebek N, Berkovic SF, Lehesjoki AE, Lesca G. Progressive Myoclonus Epilepsy Caused by a Homozygous Splicing Variant of SLC7A6OS. Ann Neurol 2020; 89:402-407. [PMID: 33085104 DOI: 10.1002/ana.25941] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 10/17/2020] [Accepted: 10/19/2020] [Indexed: 01/03/2023]
Abstract
Exome sequencing was performed in 2 unrelated families with progressive myoclonus epilepsy. Affected individuals from both families shared a rare, homozygous c.191A > G variant affecting a splice site in SLC7A6OS. Analysis of cDNA from lymphoblastoid cells demonstrated partial splice site abolition and the creation of an abnormal isoform. Quantitative reverse transcriptase polymerase chain reaction and Western blot showed a marked reduction of protein expression. Haplotype analysis identified a ~0.85cM shared genomic region on chromosome 16q encompassing the c.191A > G variant, consistent with a distant ancestor common to both families. Our results suggest that biallelic loss-of-function variants in SLC7A6OS are a novel genetic cause of progressive myoclonus epilepsy. ANN NEUROL 2021;89:402-407.
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Affiliation(s)
- Laure Mazzola
- Neurology Department, Saint-Étienne University Hospital Center, Saint-Étienne, France.,Lyon Neuroscience Research Center, Lyon, France
| | - Karen L Oliver
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia.,Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Betül Baykan
- Departments of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Mikko Muona
- Folkhälsan Research Center, Helsinki, Finland.,Blueprint Genetics, Helsinki, Finland
| | - Tarja H Joensuu
- Folkhälsan Research Center, Helsinki, Finland.,Medicum, University of Helsinki, Helsinki, Finland
| | - Carolina Courage
- Folkhälsan Research Center, Helsinki, Finland.,Medicum, University of Helsinki, Helsinki, Finland
| | - Nicolas Chatron
- Genetics Department, Lyon Civil Hospices, Lyon, France.,NeuroMyoGène Institute, University of Lyon, Claude Bernard University Lyon 1, Lyon, France
| | | | - Eudeline Alix
- Genetics Department, Lyon Civil Hospices, Lyon, France
| | - Francis Ramond
- Genetics Department, Saint-Étienne University Hospital Center, Saint-Étienne, France
| | - Renaud Touraine
- Genetics Department, Saint-Étienne University Hospital Center, Saint-Étienne, France
| | - Melanie Bahlo
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Nerses Bebek
- Departments of Neurology and Clinical Neurophysiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Samuel F Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria, Australia
| | - Anna-Elina Lehesjoki
- Folkhälsan Research Center, Helsinki, Finland.,Medicum, University of Helsinki, Helsinki, Finland
| | - Gaetan Lesca
- Genetics Department, Lyon Civil Hospices, Lyon, France.,NeuroMyoGène Institute, University of Lyon, Claude Bernard University Lyon 1, Lyon, France
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18
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Tessier TM, MacNeil KM, Mymryk JS. Piggybacking on Classical Import and Other Non-Classical Mechanisms of Nuclear Import Appear Highly Prevalent within the Human Proteome. BIOLOGY 2020; 9:biology9080188. [PMID: 32718019 PMCID: PMC7463951 DOI: 10.3390/biology9080188] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 12/23/2022]
Abstract
One of the most conserved cellular pathways among eukaryotes is the extensively studied classical protein nuclear import pathway mediated by importin-α. Classical nuclear localization signals (cNLSs) are recognized by importin-α and are highly predictable due to their abundance of basic amino acids. However, various studies in model organisms have repeatedly demonstrated that only a fraction of nuclear proteins contain identifiable cNLSs, including those that directly interact with importin-α. Using data from the Human Protein Atlas and the Human Reference Interactome, and proteomic data from BioID/protein-proximity labeling studies using multiple human importin-α proteins, we determine that nearly 50% of the human nuclear proteome does not have a predictable cNLS. Surprisingly, between 25% and 50% of previously identified human importin-α cargoes do not have predictable cNLS. Analysis of importin-α cargo without a cNLS identified an alternative basic rich motif that does not resemble a cNLS. Furthermore, several previously suspected piggybacking proteins were identified, such as those belonging to the RNA polymerase II and transcription factor II D complexes. Additionally, many components of the mediator complex interact with at least one importin-α, yet do not have a predictable cNLS, suggesting that many of the subunits may enter the nucleus through an importin-α-dependent piggybacking mechanism.
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Affiliation(s)
- Tanner M. Tessier
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada; (T.M.T.); (K.M.M.)
| | - Katelyn M. MacNeil
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada; (T.M.T.); (K.M.M.)
| | - Joe S. Mymryk
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada; (T.M.T.); (K.M.M.)
- Department of Otolaryngology, Head & Neck Surgery, The University of Western Ontario, London, ON N6A 3K7, Canada
- Department of Oncology, The University of Western Ontario, London, ON N6A 3K7, Canada
- London Regional Cancer Program, Lawson Health Research Institute, London, ON N6A 5W9, Canada
- Correspondence: ; Tel.: +1-519-685-8600 (ext. 53012)
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19
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Quintero-Cadena P, Lenstra TL, Sternberg PW. RNA Pol II Length and Disorder Enable Cooperative Scaling of Transcriptional Bursting. Mol Cell 2020; 79:207-220.e8. [DOI: 10.1016/j.molcel.2020.05.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 04/09/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022]
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20
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Contreras R, Kallemi P, González-García MP, Lazarova A, Sánchez-Serrano JJ, Sanmartín M, Rojo E. Identification of Domains and Factors Involved in MINIYO Nuclear Import. FRONTIERS IN PLANT SCIENCE 2019; 10:1044. [PMID: 31552063 PMCID: PMC6748027 DOI: 10.3389/fpls.2019.01044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 07/29/2019] [Indexed: 05/28/2023]
Abstract
The transition of stem cells from self-renewal into differentiation is tightly regulated to assure proper development of the organism. Arabidopsis MINIYO (IYO) and its mammalian orthologue RNA polymerase II associated protein 1 (RPAP1) are essential factors for initiating stem cell differentiation in plants and animals. Moreover, there is evidence suggesting that the translocation of IYO and RPAP1 from the cytosol into the nucleus functions as a molecular switch to initiate this cell fate transition. Identifying the determinants of IYO subcellular localization would allow testing if, indeed, nuclear IYO migration triggers cell differentiation and could provide tools to control this crucial developmental transition. Through transient and stable expression assays in Nicotiana benthamiana and Arabidopsis thaliana, we demonstrate that IYO contains two nuclear localization signals (NLSs), located at the N- and C-terminus of the protein, which mediate the interaction with the NLS-receptor IMPA4 and the import of the protein into the nucleus. Interestingly, IYO also interacts with GPN GTPases, which are involved in selective nuclear import of RNA polymerase II. This interaction is prevented when the G1 motif in GPN1 is mutated, suggesting that IYO binds specifically to the nucleotide-bound form of GPN1. In contrast, deleting the NLSs in IYO does not prevent the interaction with GPN1, but it interferes with import of GPN1 into the nucleus, indicating that IYO and GPN1 are co-transported as a complex that requires the IYO NLSs for import. This work unveils key domains and factors involved in IYO nuclear import, which may prove instrumental to determine how IYO and RPAP1 control stem cell differentiation.
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Affiliation(s)
| | | | | | | | | | | | - Enrique Rojo
- *Correspondence: Maite Sanmartín, , ; Enrique Rojo,
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21
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Bonomi M, Hanot S, Greenberg CH, Sali A, Nilges M, Vendruscolo M, Pellarin R. Bayesian Weighing of Electron Cryo-Microscopy Data for Integrative Structural Modeling. Structure 2018; 27:175-188.e6. [PMID: 30393052 DOI: 10.1016/j.str.2018.09.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 08/07/2018] [Accepted: 09/19/2018] [Indexed: 10/28/2022]
Abstract
Cryo-electron microscopy (cryo-EM) has become a mainstream technique for determining the structures of complex biological systems. However, accurate integrative structural modeling has been hampered by the challenges in objectively weighing cryo-EM data against other sources of information due to the presence of random and systematic errors, as well as correlations, in the data. To address these challenges, we introduce a Bayesian scoring function that efficiently and accurately ranks alternative structural models of a macromolecular system based on their consistency with a cryo-EM density map as well as other experimental and prior information. The accuracy of this approach is benchmarked using complexes of known structure and illustrated in three applications: the structural determination of the GroEL/GroES, RNA polymerase II, and exosome complexes. The approach is implemented in the open-source Integrative Modeling Platform (http://integrativemodeling.org), thus enabling integrative structure determination by combining cryo-EM data with other sources of information.
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Affiliation(s)
| | - Samuel Hanot
- Institut Pasteur, Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR 3528, C3BI USR 3756 CNRS & IP, Paris, France
| | - Charles H Greenberg
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Sciences, and California Institute for Quantitative Biomedical Sciences, University of California, San Francisco, CA 94158, USA
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Sciences, and California Institute for Quantitative Biomedical Sciences, University of California, San Francisco, CA 94158, USA
| | - Michael Nilges
- Institut Pasteur, Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR 3528, C3BI USR 3756 CNRS & IP, Paris, France
| | | | - Riccardo Pellarin
- Institut Pasteur, Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, CNRS UMR 3528, C3BI USR 3756 CNRS & IP, Paris, France.
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22
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Gpn2 and Rba50 Directly Participate in the Assembly of the Rpb3 Subcomplex in the Biogenesis of RNA Polymerase II. Mol Cell Biol 2018; 38:MCB.00091-18. [PMID: 29661922 DOI: 10.1128/mcb.00091-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/08/2018] [Indexed: 01/12/2023] Open
Abstract
RNA polymerase II (RNAPII) is one of the central enzymes in cell growth and organizational development. It is a large macromolecular complex consisting of 12 subunits. Relative to the clear definition of RNAPII structure and biological function, the molecular mechanism of how RNAPII is assembled is poorly understood, and thus the key assembly factors acting for the assembly of RNAPII remain elusive. In this study, we identified two factors, Gpn2 and Rba50, that directly participate in the assembly of RNAPII. Gpn2 and Rba50 were demonstrated to interact with Rpb12 and Rpb3, respectively. An interaction between Gpn2 and Rba50 was also demonstrated. When Gpn2 and Rba50 are functionally defective, the assembly of the Rpb3 subcomplex is disrupted, leading to defects in the assembly of RNAPII. Based on these results, we conclude that Gpn2 and Rba50 directly participate in the assembly of the Rpb3 subcomplex and subsequently the biogenesis of RNAPII.
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23
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Berg MD, Genereaux J, Karagiannis J, Brandl CJ. The Pseudokinase Domain of Saccharomyces cerevisiae Tra1 Is Required for Nuclear Localization and Incorporation into the SAGA and NuA4 Complexes. G3 (BETHESDA, MD.) 2018; 8:1943-1957. [PMID: 29626083 PMCID: PMC5982823 DOI: 10.1534/g3.118.200288] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 04/04/2018] [Indexed: 12/29/2022]
Abstract
Tra1 is an essential component of the SAGA/SLIK and NuA4 complexes in S. cerevisiae, recruiting these co-activator complexes to specific promoters. As a PIKK family member, Tra1 is characterized by a C-terminal phosphoinositide 3-kinase (PI3K) domain. Unlike other PIKK family members (e.g., Tor1, Tor2, Mec1, Tel1), Tra1 has no demonstrable kinase activity. We identified three conserved arginine residues in Tra1 that reside proximal or within the cleft between the N- and C-terminal subdomains of the PI3K domain. To establish a function for Tra1's PI3K domain and specifically the cleft region, we characterized a tra1 allele where these three arginine residues are mutated to glutamine. The half-life of the Tra1[Formula: see text] protein is reduced but its steady state level is maintained at near wild-type levels by a transcriptional feedback mechanism. The tra1[Formula: see text] allele results in slow growth under stress and alters the expression of genes also regulated by other components of the SAGA complex. Tra1[Formula: see text] is less efficiently transported to the nucleus than the wild-type protein. Likely related to this, Tra1[Formula: see text] associates poorly with SAGA/SLIK and NuA4. The ratio of Spt7SLIK to Spt7SAGA increases in the tra1[Formula: see text] strain and truncated forms of Spt20 become apparent upon isolation of SAGA/SLIK. Intragenic suppressor mutations of tra1[Formula: see text] map to the cleft region further emphasizing its importance. We propose that the PI3K domain of Tra1 is directly or indirectly important for incorporating Tra1 into SAGA and NuA4 and thus the biosynthesis and/or stability of the intact complexes.
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Affiliation(s)
- Matthew D Berg
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada N6A5C1
| | - Julie Genereaux
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada N6A5C1
| | - Jim Karagiannis
- Department of Biology, Western University, London, Ontario, Canada N6A5B7
| | - Christopher J Brandl
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada N6A5C1
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24
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Martínez-Fernández V, Garrido-Godino AI, Cuevas-Bermudez A, Navarro F. The Yeast Prefoldin Bud27. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1106:109-118. [PMID: 30484156 DOI: 10.1007/978-3-030-00737-9_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Bud27 and its human orthologue URI (unconventional prefoldin RPB5-interactor) are members of the prefoldin (PFD) family of ATP-independent molecular chaperones binding the Rpb5 subunit to all three nuclear eukaryotic RNA polymerases (RNA pols). Bud27/URI are considered to function as a scaffold protein able to assemble additional members of the prefoldin (PDF) family in both human and yeast. Bud27 and URI are not subunits of the canonical PFD/GimC complex and not only the composition but also other functions independent of the PFD/GimC complex have been described for Bud27 and URI. Bud27 interacts only with Pfd6 but no other components of the R2TP/PFDL. Furthermore previously reported interaction between Bud27 and Pfd2 was not later confirmed. These results point to major differences in the prefoldin-like complex composition between yeast and other organisms, suggesting also important differences in functions. Furthermore, this assumption could be extended to the R2TP/PFDL complex, which has been shown to differ between different organisms and has not been identified in yeast. This casts doubt on whether Bud27 cooperation with prefoldin and other components of the R2TP/PFDL modules are required for its action. This could be extended to URI and point to a role of Bud27/URI in cell functions more relevant than this previously proposed as co-prefoldin.
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Affiliation(s)
- Verónica Martínez-Fernández
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Ana Isabel Garrido-Godino
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Abel Cuevas-Bermudez
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Francisco Navarro
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain.
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25
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Leśniewska E, Boguta M. Novel layers of RNA polymerase III control affecting tRNA gene transcription in eukaryotes. Open Biol 2017; 7:rsob.170001. [PMID: 28228471 PMCID: PMC5356446 DOI: 10.1098/rsob.170001] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 01/31/2017] [Indexed: 12/20/2022] Open
Abstract
RNA polymerase III (Pol III) transcribes a limited set of short genes in eukaryotes producing abundant small RNAs, mostly tRNA. The originally defined yeast Pol III transcriptome appears to be expanding owing to the application of new methods. Also, several factors required for assembly and nuclear import of Pol III complex have been identified recently. Models of Pol III based on cryo-electron microscopy reconstructions of distinct Pol III conformations reveal unique features distinguishing Pol III from other polymerases. Novel concepts concerning Pol III functioning involve recruitment of general Pol III-specific transcription factors and distinctive mechanisms of transcription initiation, elongation and termination. Despite the short length of Pol III transcription units, mapping of transcriptionally active Pol III with nucleotide resolution has revealed strikingly uneven polymerase distribution along all genes. This may be related, at least in part, to the transcription factors bound at the internal promoter regions. Pol III uses also a specific negative regulator, Maf1, which binds to polymerase under stress conditions; however, a subset of Pol III genes is not controlled by Maf1. Among other RNA polymerases, Pol III machinery represents unique features related to a short transcript length and high transcription efficiency.
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Affiliation(s)
- Ewa Leśniewska
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
| | - Magdalena Boguta
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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26
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Webb B, Viswanath S, Bonomi M, Pellarin R, Greenberg CH, Saltzberg D, Sali A. Integrative structure modeling with the Integrative Modeling Platform. Protein Sci 2017; 27:245-258. [PMID: 28960548 DOI: 10.1002/pro.3311] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 09/23/2017] [Accepted: 09/25/2017] [Indexed: 11/06/2022]
Abstract
Building models of a biological system that are consistent with the myriad data available is one of the key challenges in biology. Modeling the structure and dynamics of macromolecular assemblies, for example, can give insights into how biological systems work, evolved, might be controlled, and even designed. Integrative structure modeling casts the building of structural models as a computational optimization problem, for which information about the assembly is encoded into a scoring function that evaluates candidate models. Here, we describe our open source software suite for integrative structure modeling, Integrative Modeling Platform (https://integrativemodeling.org), and demonstrate its use.
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Affiliation(s)
- Benjamin Webb
- California Institute for Quantitative Biosciences, University of California, San Francisco, California, 94158
| | - Shruthi Viswanath
- California Institute for Quantitative Biosciences, University of California, San Francisco, California, 94158
| | | | - Riccardo Pellarin
- Structural Bioinformatics Unit, Institut Pasteur, CNRS UMR 3528, Paris, France
| | - Charles H Greenberg
- California Institute for Quantitative Biosciences, University of California, San Francisco, California, 94158
| | - Daniel Saltzberg
- California Institute for Quantitative Biosciences, University of California, San Francisco, California, 94158
| | - Andrej Sali
- California Institute for Quantitative Biosciences, University of California, San Francisco, California, 94158
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27
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Vosnakis N, Koch M, Scheer E, Kessler P, Mély Y, Didier P, Tora L. Coactivators and general transcription factors have two distinct dynamic populations dependent on transcription. EMBO J 2017; 36:2710-2725. [PMID: 28724529 PMCID: PMC5599802 DOI: 10.15252/embj.201696035] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 06/08/2017] [Accepted: 06/15/2017] [Indexed: 12/29/2022] Open
Abstract
SAGA and ATAC are two distinct chromatin modifying co‐activator complexes with distinct enzymatic activities involved in RNA polymerase II (Pol II) transcription regulation. To investigate the mobility of co‐activator complexes and general transcription factors in live‐cell nuclei, we performed imaging experiments based on photobleaching. SAGA and ATAC, but also two general transcription factors (TFIID and TFIIB), were highly dynamic, exhibiting mainly transient associations with chromatin, contrary to Pol II, which formed more stable chromatin interactions. Fluorescence correlation spectroscopy analyses revealed that the mobile pool of the two co‐activators, as well as that of TFIID and TFIIB, can be subdivided into “fast” (free) and “slow” (chromatin‐interacting) populations. Inhibiting transcription elongation decreased H3K4 trimethylation and reduced the “slow” population of SAGA, ATAC, TFIIB and TFIID. In addition, inhibiting histone H3K4 trimethylation also reduced the “slow” populations of SAGA and ATAC. Thus, our results demonstrate that in the nuclei of live cells the equilibrium between fast and slow population of SAGA or ATAC complexes is regulated by active transcription via changes in the abundance of H3K4me3 on chromatin.
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Affiliation(s)
- Nikolaos Vosnakis
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Marc Koch
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Elisabeth Scheer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Pascal Kessler
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Yves Mély
- Université de Strasbourg, Illkirch, France.,Laboratoire de Biophotonique et Pharmacologie, Illkirch, France
| | - Pascal Didier
- Université de Strasbourg, Illkirch, France.,Laboratoire de Biophotonique et Pharmacologie, Illkirch, France
| | - László Tora
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France .,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
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28
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Cloutier P, Poitras C, Durand M, Hekmat O, Fiola-Masson É, Bouchard A, Faubert D, Chabot B, Coulombe B. R2TP/Prefoldin-like component RUVBL1/RUVBL2 directly interacts with ZNHIT2 to regulate assembly of U5 small nuclear ribonucleoprotein. Nat Commun 2017; 8:15615. [PMID: 28561026 PMCID: PMC5460035 DOI: 10.1038/ncomms15615] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 04/12/2017] [Indexed: 01/11/2023] Open
Abstract
The R2TP/Prefoldin-like (R2TP/PFDL) complex has emerged as a cochaperone complex involved in the assembly of a number of critical protein complexes including snoRNPs, nuclear RNA polymerases and PIKK-containing complexes. Here we report on the use of multiple target affinity purification coupled to mass spectrometry to identify two additional complexes that interact with R2TP/PFDL: the TSC1–TSC2 complex and the U5 small nuclear ribonucleoprotein (snRNP). The interaction between R2TP/PFDL and the U5 snRNP is mostly mediated by the previously uncharacterized factor ZNHIT2. A more general function for the zinc-finger HIT domain in binding RUVBL2 is exposed. Disruption of ZNHIT2 and RUVBL2 expression impacts the protein composition of the U5 snRNP suggesting a function for these proteins in promoting the assembly of the ribonucleoprotein. A possible implication of R2TP/PFDL as a major effector of stress-, energy- and nutrient-sensing pathways that regulate anabolic processes through the regulation of its chaperoning activity is discussed. The R2TP/Prefoldin-like cochaperone complex is involved in the assembly of a number of protein complexes. Here the authors provide evidence that RUVBL1/RUVBL2, subunits of that cochaperone complex, directly interact with ZNHIT2 to regulate assembly of U5 small ribonucleoprotein.
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Affiliation(s)
- Philippe Cloutier
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Christian Poitras
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Mathieu Durand
- Laboratory of Functional Genomics, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1E 4K8
| | - Omid Hekmat
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Émilie Fiola-Masson
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Annie Bouchard
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Denis Faubert
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Benoit Chabot
- Laboratory of Functional Genomics, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1E 4K8.,Département de Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1E 4K8
| | - Benoit Coulombe
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7.,Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada H3T 1J4
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29
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Gómez-Navarro N, Peiró-Chova L, Estruch F. Iwr1 facilitates RNA polymerase II dynamics during transcription elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:803-811. [PMID: 28258010 DOI: 10.1016/j.bbagrm.2017.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 02/16/2017] [Accepted: 02/27/2017] [Indexed: 11/16/2022]
Abstract
Iwr1 is an RNA polymerase II (RNPII) interacting protein that directs nuclear import of the enzyme which has been previously assembled in the cytoplasm. Here we present genetic and molecular evidence that links Iwr1 with transcription. Our results indicate that Iwr1 interacts with RNPII during elongation and is involved in the disassembly of the enzyme from chromatin. This function is especially important in resolving problems posed by damage-arrested RNPII, as shown by the sensitivity of iwr1 mutants to genotoxic drugs and the Iwr1's genetic interactions with RNPII degradation pathway mutants. Moreover, absence of Iwr1 causes genome instability that is enhanced by defects in the DNA repair machinery.
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Affiliation(s)
- Natalia Gómez-Navarro
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain
| | - Lorena Peiró-Chova
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain
| | - Francisco Estruch
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain.
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30
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Chan Z, Wang Y, Cao M, Gong Y, Mu Z, Wang H, Hu Y, Deng X, He XJ, Zhu JK. RDM4 modulates cold stress resistance in Arabidopsis partially through the CBF-mediated pathway. THE NEW PHYTOLOGIST 2016; 209:1527-39. [PMID: 26522658 PMCID: PMC5515388 DOI: 10.1111/nph.13727] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/25/2015] [Indexed: 05/20/2023]
Abstract
The C-REPEAT-BINDING FACTOR (CBF) pathway has important roles in plant responses to cold stress. How the CBF genes themselves are activated after cold acclimation remains poorly understood. In this study, we characterized cold tolerance of null mutant of RNA-DIRECTED DNA METHYLATION 4 (RDM4), which encodes a protein that associates with RNA polymerases Pol V and Pol II, and is required for RNA-directed DNA methylation (RdDM) in Arabidopsis. The results showed that dysfunction of RDM4 reduced cold tolerance, as evidenced by decreased survival and increased electrolyte leakage. Mutation of RDM4 resulted in extensive transcriptomic reprogramming. CBFs and CBF regulon genes were down-regulated in rdm4 but not nrpe1 (the largest subunit of PolV) mutants, suggesting that the role of RDM4 in cold stress responses is independent of the RdDM pathway. Overexpression of RDM4 constitutively increased the expression of CBFs and regulon genes and decreased cold-induced membrane injury. A great proportion of genes affected by rdm4 overlapped with those affected by CBFs. Chromatin immunoprecipitation results suggested that RDM4 is important for Pol II occupancy at the promoters of CBF2 and CBF3. We present evidence of a considerable role for RDM4 in regulating gene expression at low temperature, including the CBF pathway in Arabidopsis.
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Affiliation(s)
- Zhulong Chan
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei Province 430074, China
- Shanghai Center for Plant Stress Biology and Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yanping Wang
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei Province 430074, China
| | - Minjie Cao
- Shanghai Center for Plant Stress Biology and Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yuehua Gong
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47906, USA
- College of Life Science and Food Engineering, Yibin University, Yibin, Sichuan 644000, China
| | - Zixin Mu
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47906, USA
- College of Life Science, Northwest A&F University, Yangling, Shaan’xi 712100, China
| | - Haiqing Wang
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47906, USA
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining, Qinghai 810001, China
| | - Yuanlei Hu
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47906, USA
- College of Life Sciences, Peking University, Beijing 100871, China
| | - Xin Deng
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47906, USA
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Science, Beijing 100093, China
| | - Xin-Jian He
- National Institute of Biological Sciences, Beijing 102206, China
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology and Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47906, USA
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31
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Structure of GPN-Loop GTPase Npa3 and Implications for RNA Polymerase II Assembly. Mol Cell Biol 2015; 36:820-31. [PMID: 26711263 DOI: 10.1128/mcb.01009-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/21/2015] [Indexed: 11/20/2022] Open
Abstract
Biogenesis of the 12-subunit RNA polymerase II (Pol II) transcription complex requires so-called GPN-loop GTPases, but the function of these enzymes is unknown. Here we report the first crystal structure of a eukaryotic GPN-loop GTPase, the Saccharomyces cerevisiae enzyme Npa3 (a homolog of human GPN1, also called RPAP4, XAB1, and MBDin), and analyze its catalytic mechanism. The enzyme was trapped in a GDP-bound closed conformation and in a novel GTP analog-bound open conformation displaying a conserved hydrophobic pocket distant from the active site. We show that Npa3 has chaperone activity and interacts with hydrophobic peptide regions of Pol II subunits that form interfaces in the assembled Pol II complex. Biochemical results are consistent with a model that the hydrophobic pocket binds peptides and that this can allosterically stimulate GTPase activity and subsequent peptide release. These results suggest that GPN-loop GTPases are assembly chaperones for Pol II and other protein complexes.
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32
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Gómez-Navarro N, Estruch F. Different pathways for the nuclear import of yeast RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1354-62. [PMID: 26455955 DOI: 10.1016/j.bbagrm.2015.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/17/2015] [Accepted: 10/05/2015] [Indexed: 11/30/2022]
Abstract
Recent studies suggest that RNA polymerase II (Pol II) has to be fully assembled before being imported into the nucleus, while other reports indicate a distinct mechanism to import large and small subunits. In yeast, Iwr1 binds to the holoenzyme assembled in the cytoplasm and directs its nuclear entry. However, as IWR1 is not an essential gene, Iwr1-independent pathway(s) for the nuclear import of Pol II must exist. In this paper, we investigate the transport into the nucleus of several large and small Pol II subunits in the mutants of genes involved in Pol II biogenesis. We also analyse subcellular localization in the presence of drugs that can potentially affect Pol II nuclear import. Our results show differences in the cellular distribution between large and small subunits when Pol II biogenesis was impaired. Our data suggest that, in addition to the fully assembled holoenzyme, Pol II subunits can be imported to the nucleus, either independently or as partial assemblies, through different pathways, including passive diffusion for the small subunits.
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Affiliation(s)
- Natalia Gómez-Navarro
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universitat de València, Burjassot 46100, Spain; E.R.I. Biotecmed, Universitat de València, Burjassot, Spain
| | - Francisco Estruch
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universitat de València, Burjassot 46100, Spain; E.R.I. Biotecmed, Universitat de València, Burjassot, Spain.
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33
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Vernekar DV, Bhargava P. Yeast Bud27 modulates the biogenesis of Rpc128 and Rpc160 subunits and the assembly of RNA polymerase III. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1340-53. [PMID: 26423792 DOI: 10.1016/j.bbagrm.2015.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 01/22/2023]
Abstract
Yeast Bud27, an unconventional prefoldin is reported to affect the expression of nutrient-responsive genes, translation initiation and assembly of the multi-subunit eukaryotic RNA polymerases (pols), at a late step. We found that Bud27 associates with pol III in active as well as repressed states. Pol III transcription and occupancy at the target genes reduce with the deletion of BUD27. It promotes the interaction of pol III with the chromatin remodeler RSC found on most of the pol III targets, and with the heat shock protein Ssa4, which helps in nuclear import of the assembled pol III. Under nutrient-starvation, Ssa4-pol III interaction increases, while pol III remains inside the nucleus. Bud27 but not Ssa4 is required for RSC-pol III interaction, which reduces under nutrient-starvation. In the bud27Δ cells, total protein level of the largest pol III subunit Rpc160 but not of Rpc128, Rpc34 and Rpc53 subunits is reduced. This is accompanied by lower transcription of RPC128 gene and lower RPC160 translation due to reduced association of mRNA with the ribosomes. The resultant alteration in the normal cellular ratio of the two largest subunits of pol III core leads to reduced association of other pol III subunits and hampers the normal assembly of pol III at an early step in the cytoplasm. Our results show that Bud27 is required in multiple activities responsible for pol III biogenesis and activity.
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Affiliation(s)
- Dipti Vinayak Vernekar
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India
| | - Purnima Bhargava
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India.
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Robinson PJ, Trnka MJ, Pellarin R, Greenberg CH, Bushnell DA, Davis R, Burlingame AL, Sali A, Kornberg RD. Molecular architecture of the yeast Mediator complex. eLife 2015; 4. [PMID: 26402457 PMCID: PMC4631838 DOI: 10.7554/elife.08719] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 09/23/2015] [Indexed: 12/18/2022] Open
Abstract
The 21-subunit Mediator complex transduces regulatory information from enhancers to promoters, and performs an essential role in the initiation of transcription in all eukaryotes. Structural information on two-thirds of the complex has been limited to coarse subunit mapping onto 2-D images from electron micrographs. We have performed chemical cross-linking and mass spectrometry, and combined the results with information from X-ray crystallography, homology modeling, and cryo-electron microscopy by an integrative modeling approach to determine a 3-D model of the entire Mediator complex. The approach is validated by the use of X-ray crystal structures as internal controls and by consistency with previous results from electron microscopy and yeast two-hybrid screens. The model shows the locations and orientations of all Mediator subunits, as well as subunit interfaces and some secondary structural elements. Segments of 20–40 amino acid residues are placed with an average precision of 20 Å. The model reveals roles of individual subunits in the organization of the complex. DOI:http://dx.doi.org/10.7554/eLife.08719.001 Inside a cell, proteins are made from instructions encoded by DNA. To produce a particular protein, a section of DNA within a gene is copied into a molecule of messenger ribonucleic acid (or mRNA). This process is called transcription and is carried out by an enzyme known as RNA polymerase. Transcription begins in a region of DNA called a promoter, which is found at the start of the gene. RNA polymerase is brought to the DNA by many proteins, including the so-called Mediator complex. Mediator receives signals from within the cell and from the environment, processes the information, and instructs RNA polymerase whether to transcribe the gene or not. Mediator performs this important role in all organisms from yeast to humans, but it is not clear how it works. A crucial step towards the solution of this problem is to understand the three-dimensional structure of the complex. Previous research using a technique called ‘electron microscopy’ showed that Mediator is composed of three modules, referred to as Head, Middle and Tail. The images from electron microscopy were not sufficiently detailed to reveal the organization of the proteins within these modules. An open-source Integrative Modeling Platform (IMP for short) was recently developed to arrive at structural models of large protein complexes from a combination of experimental data and computer models. Now, Robinson, Trnka, Pellarin et al. have used this platform to study the Mediator complex. First, Robinson, Trnka, Pellarin et al. collected experimental data on the structure of the Mediator complex using two approaches called ‘chemical cross-linking’ and ‘mass spectrometry’. This data was combined with biochemical and structural information from previous studies to generate a three-dimensional model of the structure of the entire Mediator using IMP. The model is detailed enough to show the location and orientation of all the proteins in the complex. For example, a protein called Med17 connects the Head and Middle modules, while another subunit—known as Med14—spans the entire complex and makes extensive contacts with other proteins in all three modules. DOI:http://dx.doi.org/10.7554/eLife.08719.002
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Affiliation(s)
- Philip J Robinson
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Michael J Trnka
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
| | - Riccardo Pellarin
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States.,Structural Bioinformatics Unit, Paris, France
| | - Charles H Greenberg
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States
| | - David A Bushnell
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Ralph Davis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States
| | - Roger D Kornberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
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slc7a6os gene plays a critical role in defined areas of the developing CNS in zebrafish. PLoS One 2015; 10:e0119696. [PMID: 25803583 PMCID: PMC4372478 DOI: 10.1371/journal.pone.0119696] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 01/15/2015] [Indexed: 11/19/2022] Open
Abstract
The aim of this study is to shed light on the functional role of slc7a6os, a gene highly conserved in vertebrates. The Danio rerio slc7a6os gene encodes a protein of 326 amino acids with 46% identity to human SLC7A6OS and 14% to Saccharomyces cerevisiae polypeptide Iwr1. Yeast Iwr1 specifically binds RNA pol II, interacts with the basal transcription machinery and regulates the transcription of specific genes. In this study we investigated for the first time the biological role of SLC7A6OS in vertebrates. Zebrafish slc7a6os is a maternal gene that is expressed throughout development, with a prevalent localization in the developing central nervous system (CNS). The gene is also expressed, although at different levels, in various tissues of the adult fish. To determine the functional role of slc7a6os during zebrafish development, we knocked-down the gene by injecting a splice-blocking morpholino. At 24 hpf morphants show morphological defects in the CNS, particularly the interface between hindbrain and midbrain is not well-defined. At 28 hpf the morpholino injected embryos present an altered somite morphology and appear partially or completely immotile. At this stage the midbrain, hindbrain and cerebellum are compromised and not well defined compared with control embryos. The observed alterations persist at later developmental stages. Consistently, the expression pattern of two markers specifically expressed in the developing CNS, pax2a and neurod, is significantly altered in morphants. The co-injection of embryos with synthetic slc7a6os mRNA, rescues the morphant phenotype and restores the wild type expression pattern of pax2a and neurod. Our data suggest that slc7a6os might play a critical role in defined areas of the developing CNS in vertebrates, probably by regulating the expression of key genes.
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Vanacloig-Pedros E, Bets-Plasencia C, Pascual-Ahuir A, Proft M. Coordinated gene regulation in the initial phase of salt stress adaptation. J Biol Chem 2015; 290:10163-75. [PMID: 25745106 DOI: 10.1074/jbc.m115.637264] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Indexed: 01/24/2023] Open
Abstract
Stress triggers complex transcriptional responses, which include both gene activation and repression. We used time-resolved reporter assays in living yeast cells to gain insights into the coordination of positive and negative control of gene expression upon salt stress. We found that the repression of "housekeeping" genes coincides with the transient activation of defense genes and that the timing of this expression pattern depends on the severity of the stress. Moreover, we identified mutants that caused an alteration in the kinetics of this transcriptional control. Loss of function of the vacuolar H(+)-ATPase (vma1) or a defect in the biosynthesis of the osmolyte glycerol (gpd1) caused a prolonged repression of housekeeping genes and a delay in gene activation at inducible loci. Both mutants have a defect in the relocation of RNA polymerase II complexes at stress defense genes. Accordingly salt-activated transcription is delayed and less efficient upon partially respiratory growth conditions in which glycerol production is significantly reduced. Furthermore, the loss of Hog1 MAP kinase function aggravates the loss of RNA polymerase II from housekeeping loci, which apparently do not accumulate at inducible genes. Additionally the Def1 RNA polymerase II degradation factor, but not a high pool of nuclear polymerase II complexes, is needed for efficient stress-induced gene activation. The data presented here indicate that the finely tuned transcriptional control upon salt stress is dependent on physiological functions of the cell, such as the intracellular ion balance, the protective accumulation of osmolyte molecules, and the RNA polymerase II turnover.
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Affiliation(s)
- Elena Vanacloig-Pedros
- the Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Carolina Bets-Plasencia
- the Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Amparo Pascual-Ahuir
- the Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia, 46022 Valencia, Spain
| | - Markus Proft
- From the Department of Mechanisms of Plant Stress Responses, Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas, and
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Rbs1, a new protein implicated in RNA polymerase III biogenesis in yeast Saccharomyces cerevisiae. Mol Cell Biol 2015; 35:1169-81. [PMID: 25605335 DOI: 10.1128/mcb.01230-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Little is known about the RNA polymerase III (Pol III) complex assembly and its transport to the nucleus. We demonstrate that a missense cold-sensitive mutation, rpc128-1007, in the sequence encoding the C-terminal part of the second largest Pol III subunit, C128, affects the assembly and stability of the enzyme. The cellular levels and nuclear concentration of selected Pol III subunits were decreased in rpc128-1007 cells, and the association between Pol III subunits as evaluated by coimmunoprecipitation was also reduced. To identify the proteins involved in Pol III assembly, we performed a genetic screen for suppressors of the rpc128-1007 mutation and selected the Rbs1 gene, whose overexpression enhanced de novo tRNA transcription in rpc128-1007 cells, which correlated with increased stability, nuclear concentration, and interaction of Pol III subunits. The rpc128-1007 rbs1Δ double mutant shows a synthetic growth defect, indicating that rpc128-1007 and rbs1Δ function in parallel ways to negatively regulate Pol III assembly. Rbs1 physically interacts with a subset of Pol III subunits, AC19, AC40, and ABC27/Rpb5. Additionally, Rbs1 interacts with the Crm1 exportin and shuttles between the cytoplasm and nucleus. We postulate that Rbs1 binds to the Pol III complex or subcomplex and facilitates its translocation to the nucleus.
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The Not5 subunit of the ccr4-not complex connects transcription and translation. PLoS Genet 2014; 10:e1004569. [PMID: 25340856 PMCID: PMC4207488 DOI: 10.1371/journal.pgen.1004569] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 07/01/2014] [Indexed: 11/19/2022] Open
Abstract
Recent studies have suggested that a sub-complex of RNA polymerase II composed of Rpb4 and Rpb7 couples the nuclear and cytoplasmic stages of gene expression by associating with newly made mRNAs in the nucleus, and contributing to their translation and degradation in the cytoplasm. Here we show by yeast two hybrid and co-immunoprecipitation experiments, followed by ribosome fractionation and fluorescent microscopy, that a subunit of the Ccr4-Not complex, Not5, is essential in the nucleus for the cytoplasmic functions of Rpb4. Not5 interacts with Rpb4; it is required for the presence of Rpb4 in polysomes, for interaction of Rpb4 with the translation initiation factor eIF3 and for association of Rpb4 with mRNAs. We find that Rpb7 presence in the cytoplasm and polysomes is much less significant than that of Rpb4, and that it does not depend upon Not5. Hence Not5-dependence unlinks the cytoplasmic functions of Rpb4 and Rpb7. We additionally determine with RNA immunoprecipitation and native gel analysis that Not5 is needed in the cytoplasm for the co-translational assembly of RNA polymerase II. This stems from the importance of Not5 for the association of the R2TP Hsp90 co-chaperone with polysomes translating RPB1 mRNA to protect newly synthesized Rpb1 from aggregation. Hence taken together our results show that Not5 interconnects translation and transcription.
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39
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Functional diversification of maize RNA polymerase IV and V subtypes via alternative catalytic subunits. Cell Rep 2014; 9:378-390. [PMID: 25284785 DOI: 10.1016/j.celrep.2014.08.067] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/09/2014] [Accepted: 08/26/2014] [Indexed: 01/08/2023] Open
Abstract
Unlike nuclear multisubunit RNA polymerases I, II, and III, whose subunit compositions are conserved throughout eukaryotes, plant RNA polymerases IV and V are nonessential, Pol II-related enzymes whose subunit compositions are still evolving. Whereas Arabidopsis Pols IV and V differ from Pol II in four or five of their 12 subunits, respectively, and differ from one another in three subunits, proteomic analyses show that maize Pols IV and V differ from Pol II in six subunits but differ from each other only in their largest subunits. Use of alternative catalytic second subunits, which are nonredundant for development and paramutation, yields at least two subtypes of Pol IV and three subtypes of Pol V in maize. Pol IV/Pol V associations with MOP1, RMR1, AGO121, Zm_DRD1/CHR127, SHH2a, and SHH2b extend parallels between paramutation in maize and the RNA-directed DNA methylation pathway in Arabidopsis.
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40
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Gpn1 and Gpn3 associate tightly and their protein levels are mutually dependent in mammalian cells. FEBS Lett 2014; 588:3823-9. [DOI: 10.1016/j.febslet.2014.08.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 08/03/2014] [Accepted: 08/28/2014] [Indexed: 11/24/2022]
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41
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Cieśla M, Mierzejewska J, Adamczyk M, Farrants AKÖ, Boguta M. Fructose bisphosphate aldolase is involved in the control of RNA polymerase III-directed transcription. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1103-10. [DOI: 10.1016/j.bbamcr.2014.02.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 01/28/2014] [Accepted: 02/13/2014] [Indexed: 10/25/2022]
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42
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Abstract
RNA-directed DNA methylation (RdDM) is the major small RNA-mediated epigenetic pathway in plants. RdDM requires a specialized transcriptional machinery that comprises two plant-specific RNA polymerases - Pol IV and Pol V - and a growing number of accessory proteins, the functions of which in the RdDM mechanism are only partially understood. Recent work has revealed variations in the canonical RdDM pathway and identified factors that recruit Pol IV and Pol V to specific target sequences. RdDM, which transcriptionally represses a subset of transposons and genes, is implicated in pathogen defence, stress responses and reproduction, as well as in interallelic and intercellular communication.
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43
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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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44
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Forget D, Lacombe AA, Cloutier P, Lavallée-Adam M, Blanchette M, Coulombe B. Nuclear import of RNA polymerase II is coupled with nucleocytoplasmic shuttling of the RNA polymerase II-associated protein 2. Nucleic Acids Res 2013; 41:6881-91. [PMID: 23723243 PMCID: PMC3737550 DOI: 10.1093/nar/gkt455] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The RNA polymerase II (RNAP II)-associated protein (RPAP) 2 has been discovered through its association with various subunits of RNAP II in affinity purification coupled with mass spectrometry experiments. Here, we show that RPAP2 is a mainly cytoplasmic protein that shuttles between the cytoplasm and the nucleus. RPAP2 shuttling is tightly coupled with nuclear import of RNAP II, as RPAP2 silencing provokes abnormal accumulation of RNAP II in the cytoplasmic space. Most notably, RPAP4/GPN1 silencing provokes the retention of RPAP2 in the nucleus. Our results support a model in which RPAP2 enters the nucleus in association with RNAP II and returns to the cytoplasm in association with the GTPase GPN1/RPAP4. Although binding of RNAP II to RPAP2 is mediated by an N-terminal domain (amino acids 1–170) that contains a nuclear retention domain, and binding of RPAP4/GPN1 to RPAP2 occurs through a C-terminal domain (amino acids 156–612) that has a dominant cytoplasmic localization domain. In conjunction with previously published data, our results have important implications, as they indicate that RPAP2 controls gene expression by two distinct mechanisms, one that targets RNAP II activity during transcription and the other that controls availability of RNAP II in the nucleus.
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Affiliation(s)
- Diane Forget
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada H2W 1R7, McGill Centre for Bioinformatics and School of Computer Science, McGill University, Montréal, Québec, Canada H3A 2B4
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45
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Rtp1p is a karyopherin-like protein required for RNA polymerase II biogenesis. Mol Cell Biol 2013; 33:1756-67. [PMID: 23438601 DOI: 10.1128/mcb.01449-12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The assembly and nuclear transport of RNA polymerase II (RNA pol II) are processes that require the participation of many auxiliary factors. In a yeast genetic screen, we identified a previously uncharacterized gene, YMR185w (renamed RTP1), which encodes a protein required for the nuclear import of RNA pol II. Using protein affinity purification coupled to mass spectrometry, we identified interactions between Rtp1p and members of the R2TP complex. Rtp1p also interacts, to a different extent, with several RNA pol II subunits. The pattern of interactions is compatible with a role for Rtp1p as an assembly factor that participates in the formation of the Rpb2/Rpb3 subassembly complex and its binding to the Rpb1p-containing subcomplex. Besides, Rtp1p has a molecular architecture characteristic of karyopherins, composed of HEAT repeats, and is able to interact with phenylalanine-glycine-containing nucleoporins. Our results define Rtp1p as a new component of the RNA pol II biogenesis machinery that plays roles in subunit assembly and likely in transport through the nuclear pore complex.
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46
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Mirón-García MC, Garrido-Godino AI, García-Molinero V, Hernández-Torres F, Rodríguez-Navarro S, Navarro F. The prefoldin bud27 mediates the assembly of the eukaryotic RNA polymerases in an rpb5-dependent manner. PLoS Genet 2013; 9:e1003297. [PMID: 23459708 PMCID: PMC3573130 DOI: 10.1371/journal.pgen.1003297] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 12/18/2012] [Indexed: 01/22/2023] Open
Abstract
The unconventional prefoldin URI/RMP, in humans, and its orthologue in yeast, Bud27, have been proposed to participate in the biogenesis of the RNA polymerases. However, this role of Bud27 has not been confirmed and is poorly elucidated. Our data help clarify the mechanisms governing biogenesis of the three eukaryotic RNA pols. We show evidence that Bud27 is the first example of a protein that participates in the biogenesis of the three eukaryotic RNA polymerases and the first example of a protein modulating their assembly instead of their nuclear transport. In addition we demonstrate that the role of Bud27 in RNA pols biogenesis depends on Rpb5. In fact, lack of BUD27 affects growth and leads to a substantial accumulation of the three RNA polymerases in the cytoplasm, defects offset by the overexpression of RPB5. Supporting this, our data demonstrate that the lack of Bud27 affects the correct assembly of Rpb5 and Rpb6 to the three RNA polymerases, suggesting that this process occurs in the cytoplasm and is a required step prior to nuclear import. Also, our data support the view that Rpb5 and Rpb6 assemble somewhat later than the rest of the complexes. Furthermore, Bud27 Rpb5-binding but not PFD-binding domain is necessary for RNA polymerases biogenesis. In agreement, we also demonstrate genetic interactions between BUD27, RPB5, and RPB6. Bud27 shuttles between the nucleus and the cytoplasm in an Xpo1-independent manner, and also independently of microtubule polarization and possibly independently of its association with the RNA pols. Our data also suggest that the role of Bud27 in RNA pols biogenesis is independent of the chaperone prefoldin (PFD) complex and of Iwr1. Finally, the role of URI seems to be conserved in humans, suggesting conserved mechanisms in RNA pols biogenesis. The mechanisms governing the assembly and the transport of the three eukaryotic RNA polymerases to the nucleus are in discussion. Interesting papers have demonstrated the participation of some proteins in the assembly of the nuclear RNA polymerases and in their transport to the nucleus, but the mechanisms involved are poorly understood. Our data help clarify the mechanisms governing biogenesis of the three eukaryotic RNA pols and demonstrate that the prefoldin Bud27 of Saccharomyces cerevisiae mediates the correct assembly of the three complexes prior to their translocation to the nucleus, in a process which is dependent on Rpb5. In addition, our data support the view that, during the assembly of the RNA pols, Rpb5 and Rpb6 assemble rather late compared to the rest of the complexes. Furthermore, this role of Bud27 seems to be specific, as it is not extended to other prefoldin members. Finally, the role of Bud27 seems to be conserved in humans, suggesting conserved mechanisms in RNA pols biogenesis.
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Affiliation(s)
- María Carmen Mirón-García
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Ana Isabel Garrido-Godino
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Varinia García-Molinero
- Centro de Investigación Príncipe Felipe (CIPF), Gene Expression Coupled with RNA Transport Laboratory, Valencia, Spain
| | - Francisco Hernández-Torres
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Susana Rodríguez-Navarro
- Centro de Investigación Príncipe Felipe (CIPF), Gene Expression Coupled with RNA Transport Laboratory, Valencia, Spain
| | - Francisco Navarro
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
- * E-mail:
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47
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Mastroeni D, Chouliaras L, Grover A, Liang WS, Hauns K, Rogers J, Coleman PD. Reduced RAN expression and disrupted transport between cytoplasm and nucleus; a key event in Alzheimer's disease pathophysiology. PLoS One 2013; 8:e53349. [PMID: 23308199 PMCID: PMC3540085 DOI: 10.1371/journal.pone.0053349] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 11/27/2012] [Indexed: 12/29/2022] Open
Abstract
Transcription of DNA is essential for cell maintenance and survival; inappropriate localization of proteins that are involved in transcription would be catastrophic. In Alzheimer's disease brains, and in vitro studies, we have found qualitative and quantitative deficits in transport into the nucleus of DNA methyltransferase 1 (DNMT1) and RNA polymerase II (RNA pol II), accompanied by their abnormal sequestration in the cytoplasm. RAN (RAs-related Nuclear protein) knockdown, by siRNA and oligomeric Aβ42 treatment in neurons, replicate human data which indicate that transport disruption in AD may be mechanistically linked to reduced expression of RAN, a pivotal molecule in nucleocytoplasmic transport. In vitro studies also indicate a significant role for oligomeric Aβ42 in the observed phenomena. We propose a model in which reduced transcription regulators in the nucleus and their increased presence in the cytoplasm may lead to many of the cellular manifestations of Alzheimer's disease.
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Affiliation(s)
- Diego Mastroeni
- L. J. Roberts Alzheimer’s Disease Center, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
- School for Mental Health and Neuroscience (MHeNS), Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European Graduate School of Neuroscience (EURON), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Leonidas Chouliaras
- School for Mental Health and Neuroscience (MHeNS), Department of Psychiatry and Neuropsychology, Faculty of Health, Medicine and Life Sciences, European Graduate School of Neuroscience (EURON), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Andrew Grover
- L. J. Roberts Alzheimer’s Disease Center, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Winnie S. Liang
- Collaborative Sequencing Center, Translational Genomics Research Institute, Phoenix, Arizona, United States of America
| | - Kevin Hauns
- L. J. Roberts Alzheimer’s Disease Center, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Joseph Rogers
- L. J. Roberts Alzheimer’s Disease Center, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
| | - Paul D. Coleman
- L. J. Roberts Alzheimer’s Disease Center, Banner Sun Health Research Institute, Sun City, Arizona, United States of America
- * E-mail:
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48
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Biogenesis of RNA polymerases II and III requires the conserved GPN small GTPases in Saccharomyces cerevisiae. Genetics 2012; 193:853-64. [PMID: 23267056 PMCID: PMC3584002 DOI: 10.1534/genetics.112.148726] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The GPN proteins are a poorly characterized and deeply evolutionarily conserved family of three paralogous small GTPases, Gpn1, 2, and 3. The founding member, GPN1/NPA3/XAB1, is proposed to function in nuclear import of RNA polymerase II along with a recently described protein called Iwr1. Here we show that the previously uncharacterized protein Gpn2 binds both Gpn3 and Npa3/Gpn1 and that temperature-sensitive alleles of Saccharomyces cerevisiae GPN2 and GPN3 exhibit genetic interactions with RNA polymerase II mutants, hypersensitivity to transcription inhibition, and defects in RNA polymerase II nuclear localization. Importantly, we identify previously unrecognized RNA polymerase III localization defects in GPN2, GPN3, and IWR1 mutant backgrounds but find no localization defects of unrelated nuclear proteins or of RNA polymerase I. Previously, it was unclear whether the GPN proteins and Iwr1 had overlapping function in RNA polymerase II assembly or import. In this study, we show that the nuclear import defect of iwr1Δ, but not the GPN2 or GPN3 mutant defects, is partially suppressed by fusion of a nuclear localization signal to the RNA polymerase II subunit Rpb3. These data, combined with strong genetic interactions between GPN2 and IWR1, suggest that the GPN proteins function upstream of Iwr1 in RNA polymerase II and III biogenesis. We propose that the three GPN proteins execute a common, and likely essential, function in RNA polymerase assembly and transport.
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Lavallée-Adam M, Rousseau J, Domecq C, Bouchard A, Forget D, Faubert D, Blanchette M, Coulombe B. Discovery of cell compartment specific protein-protein interactions using affinity purification combined with tandem mass spectrometry. J Proteome Res 2012; 12:272-81. [PMID: 23157168 DOI: 10.1021/pr300778b] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Affinity purification combined with tandem mass spectrometry (AP-MS/MS) is a well-established method used to discover interaction partners for a given protein of interest. Because most AP-MS/MS approaches are performed using the soluble fraction of whole cell extracts (WCE), information about the cellular compartments where the interactions occur is lost. More importantly, classical AP-MS/MS often fails to identify interactions that take place in the nonsoluble fraction of the cell, for example, on the chromatin or membranes; consequently, protein complexes that are less soluble are underrepresented. In this paper, we introduce a method called multiple cell compartment AP-MS/MS (MCC-AP-MS/MS), which identifies the interactions of a protein independently in three fractions of the cell: the cytoplasm, the nucleoplasm, and the chromatin. We show that this fractionation improves the sensitivity of the method when compared to the classical affinity purification procedure using soluble WCE while keeping a very high specificity. Using three proteins known to localize in various cell compartments as baits, the CDK9 subunit of transcription elongation factor P-TEFb, the RNA polymerase II (RNAP II)-associated protein 4 (RPAP4), and the largest subunit of RNAP II, POLR2A, we show that MCC-AP-MS/MS reproducibly yields fraction-specific interactions. Finally, we demonstrate that this improvement in sensitivity leads to the discovery of novel interactions of RNAP II carboxyl-terminal domain (CTD) interacting domain (CID) proteins with POLR2A.
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Affiliation(s)
- Mathieu Lavallée-Adam
- McGill Centre for Bioinformatics and School of Computer Science, McGill University, Montréal, Québec H3A 2B4, Canada
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Abstract
The dms4 (defective in meristem silencing 4) mutant of Arabidopsis thaliana is unique in having defects in both RNA-directed DNA methylation (RdDM) and plant development. DMS4 is an evolutionarily conserved, putative transcription factor of the Iwr1 (interacts with RNA polymerase II) type. DMS4 interacts with Pol II and also with RNA polymerases IV and V, which function in RdDM. Interactions with multiple polymerases may account for the diverse phenotypic effects of dms4 mutations. To dissect further the roles of DMS4 in RdDM and development, we performed a genetic suppressor screen using the dms4-1 allele, which contains in the sixth intron a splice site acceptor mutation that alters splicing and destroys the open reading frame. Following mutagenesis of dms4-1 seeds using ethyl methanesulfonate (EMS), we retrieved four dominant intragenic suppressor mutations that restored DMS4 function and wild-type phenotypes. Three of the four intragenic suppressor mutations created new splice site acceptors, which resulted in reestablishment of the wild-type open reading frame. Remarkably, the intragenic suppressor mutations were recovered at frequencies ranging from 35 to 150 times higher than expected for standard EMS mutagenesis in Arabidopsis. Whole-genome sequencing did not reveal an elevated mutation frequency genome-wide, indicating that the apparent hypermutation was confined to four specific sites in the dms4 gene. The localized high mutation frequency correlated with restoration of DMS4 function implies an efficient mechanism for targeted mutagenesis or selection of more fit revertant cells in the shoot apical meristem, thereby rapidly restoring a wild-type phenotype that is transmitted to future generations.
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