1
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Chen X, Liu W, Wang Q, Wang X, Ren Y, Qu X, Li W, Xu Y. Structural visualization of transcription initiation in action. Science 2023; 382:eadi5120. [PMID: 38127763 DOI: 10.1126/science.adi5120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 11/11/2023] [Indexed: 12/23/2023]
Abstract
Transcription initiation is a complex process, and its mechanism is incompletely understood. We determined the structures of de novo transcribing complexes TC2 to TC17 with RNA polymerase II halted on G-less promoters when nascent RNAs reach 2 to 17 nucleotides in length, respectively. Connecting these structures generated a movie and a working model. As initially synthesized RNA grows, general transcription factors (GTFs) remain bound to the promoter and the transcription bubble expands. Nucleoside triphosphate (NTP)-driven RNA-DNA translocation and template-strand accumulation in a nearly sealed channel may promote the transition from initially transcribing complexes (ITCs) (TC2 to TC9) to early elongation complexes (EECs) (TC10 to TC17). Our study shows dynamic processes of transcription initiation and reveals why ITCs require GTFs and bubble expansion for initial RNA synthesis, whereas EECs need GTF dissociation from the promoter and bubble collapse for promoter escape.
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Affiliation(s)
- Xizi Chen
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Weida Liu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Qianmin Wang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Xinxin Wang
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Yulei Ren
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Xuechun Qu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Wanjun Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, New Cornerstone Science Laboratory, State Key Laboratory of Genetic Engineering, Department of Biochemistry and Biophysics, School of Life Sciences, Shanghai Key Laboratory of Radiation Oncology, and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai 200032, China
- The International Co-laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, China, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China
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2
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Lin G, Barnes CO, Weiss S, Dutagaci B, Qiu C, Feig M, Song J, Lyubimov A, Cohen AE, Kaplan CD, Calero G. Structural basis of transcription: RNA Polymerase II substrate binding and metal coordination at 3.0 Å using a free-electron laser. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.22.559052. [PMID: 37790421 PMCID: PMC10543002 DOI: 10.1101/2023.09.22.559052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Catalysis and translocation of multi-subunit DNA-directed RNA polymerases underlie all cellular mRNA synthesis. RNA polymerase II (Pol II) synthesizes eukaryotic pre-mRNAs from a DNA template strand buried in its active site. Structural details of catalysis at near atomic resolution and precise arrangement of key active site components have been elusive. Here we present the free electron laser (FEL) structure of a matched ATP-bound Pol II, revealing the full active site interaction network at the highest resolution to date, including the trigger loop (TL) in the closed conformation, bonafide occupancy of both site A and B Mg2+, and a putative third (site C) Mg2+ analogous to that described for some DNA polymerases but not observed previously for cellular RNA polymerases. Molecular dynamics (MD) simulations of the structure indicate that the third Mg2+ is coordinated and stabilized at its observed position. TL residues provide half of the substrate binding pocket while multiple TL/bridge helix (BH) interactions induce conformational changes that could propel translocation upon substrate hydrolysis. Consistent with TL/BH communication, a FEL structure and MD simulations of the hyperactive Rpb1 T834P bridge helix mutant reveals rearrangement of some active site interactions supporting potential plasticity in active site function and long-distance effects on both the width of the central channel and TL conformation, likely underlying its increased elongation rate at the expense of fidelity.
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Affiliation(s)
- Guowu Lin
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA 15261 USA
| | - Christopher O Barnes
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Simon Weiss
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA 15261 USA
| | - Bercem Dutagaci
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing MI 48824 USA
| | - Chenxi Qiu
- Department of Genetics, Harvard Medical School, Boston MA 02115 USA
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing MI 48824 USA
| | - Jihnu Song
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Artem Lyubimov
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Aina E Cohen
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh PA 15260 USA
| | - Guillermo Calero
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA 15261 USA
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3
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Kirsch SH, Haeckl FPJ, Müller R. Beyond the approved: target sites and inhibitors of bacterial RNA polymerase from bacteria and fungi. Nat Prod Rep 2022; 39:1226-1263. [PMID: 35507039 DOI: 10.1039/d1np00067e] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Covering: 2016 to 2022RNA polymerase (RNAP) is the central enzyme in bacterial gene expression representing an attractive and validated target for antibiotics. Two well-known and clinically approved classes of natural product RNAP inhibitors are the rifamycins and the fidaxomycins. Rifampicin (Rif), a semi-synthetic derivative of rifamycin, plays a crucial role as a first line antibiotic in the treatment of tuberculosis and a broad range of bacterial infections. However, more and more pathogens such as Mycobacterium tuberculosis develop resistance, not only against Rif and other RNAP inhibitors. To overcome this problem, novel RNAP inhibitors exhibiting different target sites are urgently needed. This review includes recent developments published between 2016 and today. Particular focus is placed on novel findings concerning already known bacterial RNAP inhibitors, the characterization and development of new compounds isolated from bacteria and fungi, and providing brief insights into promising new synthetic compounds.
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Affiliation(s)
- Susanne H Kirsch
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University Campus, 66123 Saarbrücken, Germany. .,German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany
| | - F P Jake Haeckl
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University Campus, 66123 Saarbrücken, Germany. .,German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany
| | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University Campus, 66123 Saarbrücken, Germany. .,German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany.,Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
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4
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Gajos M, Jasnovidova O, van Bömmel A, Freier S, Vingron M, Mayer A. Conserved DNA sequence features underlie pervasive RNA polymerase pausing. Nucleic Acids Res 2021; 49:4402-4420. [PMID: 33788942 PMCID: PMC8096220 DOI: 10.1093/nar/gkab208] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/05/2021] [Accepted: 03/15/2021] [Indexed: 12/17/2022] Open
Abstract
Pausing of transcribing RNA polymerase is regulated and creates opportunities to control gene expression. Research in metazoans has so far mainly focused on RNA polymerase II (Pol II) promoter-proximal pausing leaving the pervasive nature of pausing and its regulatory potential in mammalian cells unclear. Here, we developed a pause detecting algorithm (PDA) for nucleotide-resolution occupancy data and a new native elongating transcript sequencing approach, termed nested NET-seq, that strongly reduces artifactual peaks commonly misinterpreted as pausing sites. Leveraging PDA and nested NET-seq reveal widespread genome-wide Pol II pausing at single-nucleotide resolution in human cells. Notably, the majority of Pol II pauses occur outside of promoter-proximal gene regions primarily along the gene-body of transcribed genes. Sequence analysis combined with machine learning modeling reveals DNA sequence properties underlying widespread transcriptional pausing including a new pause motif. Interestingly, key sequence determinants of RNA polymerase pausing are conserved between human cells and bacteria. These studies indicate pervasive sequence-induced transcriptional pausing in human cells and the knowledge of exact pause locations implies potential functional roles in gene expression.
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Affiliation(s)
- Martyna Gajos
- Otto-Warburg-Laboratory, Max Planck Institute for Molecular Genetics, Berlin 14195, Germany.,Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin 14195, Germany
| | - Olga Jasnovidova
- Otto-Warburg-Laboratory, Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Alena van Bömmel
- Department of Mathematics and Computer Science, Freie Universität Berlin, Berlin 14195, Germany.,Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Susanne Freier
- Otto-Warburg-Laboratory, Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Martin Vingron
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Andreas Mayer
- Otto-Warburg-Laboratory, Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
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5
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Abstract
Gene transcription by RNA polymerase II (Pol II) is the first step in the expression of the eukaryotic genome and a focal point for cellular regulation during development, differentiation, and responses to the environment. Two decades after the determination of the structure of Pol II, the mechanisms of transcription have been elucidated with studies of Pol II complexes with nucleic acids and associated proteins. Here we provide an overview of the nearly 200 available Pol II complex structures and summarize how these structures have elucidated promoter-dependent transcription initiation, promoter-proximal pausing and release of Pol II into active elongation, and the mechanisms that Pol II uses to navigate obstacles such as nucleosomes and DNA lesions. We predict that future studies will focus on how Pol II transcription is interconnected with chromatin transitions, RNA processing, and DNA repair.
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Affiliation(s)
- Sara Osman
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany;,
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany;,
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6
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KIreeva M, Trang C, Matevosyan G, Turek-Herman J, Chasov V, Lubkowska L, Kashlev M. RNA-DNA and DNA-DNA base-pairing at the upstream edge of the transcription bubble regulate translocation of RNA polymerase and transcription rate. Nucleic Acids Res 2019; 46:5764-5775. [PMID: 29771376 PMCID: PMC6009650 DOI: 10.1093/nar/gky393] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 04/30/2018] [Indexed: 12/19/2022] Open
Abstract
Translocation of RNA polymerase (RNAP) along DNA may be rate-limiting for transcription elongation. The Brownian ratchet model posits that RNAP rapidly translocates back and forth until the post-translocated state is stabilized by NTP binding. An alternative model suggests that RNAP translocation is slow and poorly reversible. To distinguish between these two models, we take advantage of an observation that pyrophosphorolysis rates directly correlate with the abundance of the pre-translocated fraction. Pyrophosphorolysis by RNAP stabilized in the pre-translocated state by bacteriophage HK022 protein Nun was used as a reference point to determine the pre-translocated fraction in the absence of Nun. The stalled RNAP preferentially occupies the post-translocated state. The forward translocation rate depends, among other factors, on melting of the RNA–DNA base pair at the upstream edge of the transcription bubble. DNA–DNA base pairing immediately upstream from the RNA–DNA hybrid stabilizes the post-translocated state. This mechanism is conserved between E. coli RNAP and S. cerevisiae RNA polymerase II and is partially dependent on the lid domain of the catalytic subunit. Thus, the RNA–DNA hybrid and DNA reannealing at the upstream edge of the transcription bubble emerge as targets for regulation of the transcription elongation rate.
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Affiliation(s)
- Maria KIreeva
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Cyndi Trang
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Gayane Matevosyan
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Joshua Turek-Herman
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Vitaly Chasov
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Lucyna Lubkowska
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Mikhail Kashlev
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
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7
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Abstract
In all living organisms, the flow of genetic information is a two-step process: first DNA is transcribed into RNA, which is subsequently used as template for protein synthesis during translation. In bacteria, archaea and eukaryotes, transcription is carried out by multi-subunit RNA polymerases (RNAPs) sharing a conserved architecture of the RNAP core. RNAPs catalyse the highly accurate polymerisation of RNA from NTP building blocks, utilising DNA as template, being assisted by transcription factors during the initiation, elongation and termination phase of transcription. The complexity of this highly dynamic process is reflected in the intricate network of protein-protein and protein-nucleic acid interactions in transcription complexes and the substantial conformational changes of the RNAP as it progresses through the transcription cycle.In this chapter, we will first briefly describe the early work that led to the discovery of multisubunit RNAPs. We will then discuss the three-dimensional organisation of RNAPs from the bacterial, archaeal and eukaryotic domains of life, highlighting the conserved nature, but also the domain-specific features of the transcriptional apparatus. Another section will focus on transcription factors and their role in regulating the RNA polymerase throughout the different phases of the transcription cycle. This includes a discussion of the molecular mechanisms and dynamic events that govern transcription initiation, elongation and termination.
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8
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Belogurov GA, Artsimovitch I. The Mechanisms of Substrate Selection, Catalysis, and Translocation by the Elongating RNA Polymerase. J Mol Biol 2019; 431:3975-4006. [PMID: 31153902 DOI: 10.1016/j.jmb.2019.05.042] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 05/24/2019] [Accepted: 05/24/2019] [Indexed: 11/15/2022]
Abstract
Multi-subunit DNA-dependent RNA polymerases synthesize all classes of cellular RNAs, ranging from short regulatory transcripts to gigantic messenger RNAs. RNA polymerase has to make each RNA product in just one try, even if it takes millions of successive nucleotide addition steps. During each step, RNA polymerase selects a correct substrate, adds it to a growing chain, and moves one nucleotide forward before repeating the cycle. However, RNA synthesis is anything but monotonous: RNA polymerase frequently pauses upon encountering mechanical, chemical and torsional barriers, sometimes stepping back and cleaving off nucleotides from the growing RNA chain. A picture in which these intermittent dynamics enable processive, accurate, and controllable RNA synthesis is emerging from complementary structural, biochemical, computational, and single-molecule studies. Here, we summarize our current understanding of the mechanism and regulation of the on-pathway transcription elongation. We review the details of substrate selection, catalysis, proofreading, and translocation, focusing on rate-limiting steps, structural elements that modulate them, and accessory proteins that appear to control RNA polymerase translocation.
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Affiliation(s)
| | - Irina Artsimovitch
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
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9
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The Role of Pyrophosphorolysis in the Initiation-to-Elongation Transition by E. coli RNA Polymerase. J Mol Biol 2019; 431:2528-2542. [PMID: 31029704 DOI: 10.1016/j.jmb.2019.04.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/13/2019] [Accepted: 04/15/2019] [Indexed: 02/02/2023]
Abstract
RNA polymerase can cleave a phosphodiester bond at the 3' end of a nascent RNA in the presence of pyrophosphate producing NTP. Pyrophosphorolysis has been characterized during elongation steps of transcription where its rate is significantly slower than the forward rate of NMP addition. In contrast, we report here that pyrophosphorolysis can occur in a millisecond time scale during the transition of Escherichia coli RNA polymerase from initiation to elongation at the psbA2 promoter. This rapid pyrophosphorolysis occurs during productive RNA synthesis as opposed to abortive RNA synthesis. Dissociation of σ70 or RNA extension beyond nine nucleotides dramatically reduces the rate of pyrophosphorolysis. We argue that the rapid pyrophosphorolysis allows iterative cycles of cleavage and re-synthesis of the 3' phosphodiester bond by the productive complexes in the early stage of transcription. This iterative process may provide an opportunity for the σ70 to dissociate from the RNA exit channel of the enzyme, enabling RNA to extend through the channel.
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10
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Nedialkov YA, Opron K, Caudill HL, Assaf F, Anderson AJ, Cukier RI, Wei G, Burton ZF. Hinge action versus grip in translocation by RNA polymerase. Transcription 2017; 9:1-16. [PMID: 28853995 PMCID: PMC5791816 DOI: 10.1080/21541264.2017.1330179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Based on molecular dynamics simulations and functional studies, a conformational mechanism is posited for forward translocation by RNA polymerase (RNAP). In a simulation of a ternary elongation complex, the clamp and downstream cleft were observed to close. Hinges within the bridge helix and trigger loop supported generation of translocation force against the RNA-DNA hybrid resulting in opening of the furthest upstream i-8 RNA-DNA bp, establishing conditions for RNAP sliding. The β flap tip helix and the most N-terminal β' Zn finger engage the RNA, indicating a path of RNA threading out of the exit channel. Because the β flap tip connects to the RNAP active site through the β subunit double-Ψ-β-barrel and the associated sandwich barrel hybrid motif (also called the flap domain), the RNAP active site is coupled to the RNA exit channel and to the translocation of RNA-DNA. Using an exonuclease III assay to monitor translocation of RNAP elongation complexes, we show that K+ and Mg2+ and also an RNA 3'-OH or a 3'-H2 affect RNAP sliding. Because RNAP grip to template suggests a sticky translocation mechanism, and because grip is enhanced by increasing K+ and Mg2+concentration, biochemical assays are consistent with a conformational change that drives forward translocation as observed in simulations. Mutational analysis of the bridge helix indicates that 778-GARKGL-783 (Escherichia coli numbering) is a homeostatic hinge that undergoes multiple bends to compensate for complex conformational dynamics during phosphodiester bond formation and translocation.
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Affiliation(s)
- Yuri A Nedialkov
- a Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA.,b Department of Microbiology , The Ohio State University , Columbus , OH , USA
| | - Kristopher Opron
- a Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA.,c Department of Mathematics , Michigan State University , E. Lansing , MI , USA.,d Bioinformatics Core , North Campus Research Complex (NCRC) , Ann Arbor , MI , USA
| | - Hailey L Caudill
- a Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA
| | - Fadi Assaf
- a Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA
| | - Amanda J Anderson
- a Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA
| | - Robert I Cukier
- e Department of Chemistry , Michigan State University , E. Lansing , MI , USA
| | - Guowei Wei
- c Department of Mathematics , Michigan State University , E. Lansing , MI , USA
| | - Zachary F Burton
- a Department of Biochemistry and Molecular Biology , Michigan State University , E. Lansing , MI , USA
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11
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Lee J, Borukhov S. Bacterial RNA Polymerase-DNA Interaction-The Driving Force of Gene Expression and the Target for Drug Action. Front Mol Biosci 2016; 3:73. [PMID: 27882317 PMCID: PMC5101437 DOI: 10.3389/fmolb.2016.00073] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/24/2016] [Indexed: 11/17/2022] Open
Abstract
DNA-dependent multisubunit RNA polymerase (RNAP) is the key enzyme of gene expression and a target of regulation in all kingdoms of life. It is a complex multifunctional molecular machine which, unlike other DNA-binding proteins, engages in extensive and dynamic interactions (both specific and nonspecific) with DNA, and maintains them over a distance. These interactions are controlled by DNA sequences, DNA topology, and a host of regulatory factors. Here, we summarize key recent structural and biochemical studies that elucidate the fine details of RNAP-DNA interactions during initiation. The findings of these studies help unravel the molecular mechanisms of promoter recognition and open complex formation, initiation of transcript synthesis and promoter escape. We also discuss most current advances in the studies of drugs that specifically target RNAP-DNA interactions during transcription initiation and elongation.
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Affiliation(s)
- Jookyung Lee
- Department of Cell Biology, Rowan University School of Osteopathic Medicine Stratford, NJ, USA
| | - Sergei Borukhov
- Department of Cell Biology, Rowan University School of Osteopathic Medicine Stratford, NJ, USA
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12
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Hwang CS, Xu L, Wang W, Ulrich S, Zhang L, Chong J, Shin JH, Huang X, Kool ET, McKenna CE, Wang D. Functional interplay between NTP leaving group and base pair recognition during RNA polymerase II nucleotide incorporation revealed by methylene substitution. Nucleic Acids Res 2016; 44:3820-8. [PMID: 27060150 PMCID: PMC4857003 DOI: 10.1093/nar/gkw220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 03/18/2016] [Accepted: 03/21/2016] [Indexed: 02/07/2023] Open
Abstract
RNA polymerase II (pol II) utilizes a complex interaction network to select and incorporate correct nucleoside triphosphate (NTP) substrates with high efficiency and fidelity. Our previous 'synthetic nucleic acid substitution' strategy has been successfully applied in dissecting the function of nucleic acid moieties in pol II transcription. However, how the triphosphate moiety of substrate influences the rate of P-O bond cleavage and formation during nucleotide incorporation is still unclear. Here, by employing β,γ-bridging atom-'substituted' NTPs, we elucidate how the methylene substitution in the pyrophosphate leaving group affects cognate and non-cognate nucleotide incorporation. Intriguingly, the effect of the β,γ-methylene substitution on the non-cognate UTP/dT scaffold (∼3-fold decrease in kpol) is significantly different from that of the cognate ATP/dT scaffold (∼130-fold decrease in kpol). Removal of the wobble hydrogen bonds in U:dT recovers a strong response to methylene substitution of UTP. Our kinetic and modeling studies are consistent with a unique altered transition state for bond formation and cleavage for UTP/dT incorporation compared with ATP/dT incorporation. Collectively, our data reveals the functional interplay between NTP triphosphate moiety and base pair hydrogen bonding recognition during nucleotide incorporation.
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Affiliation(s)
- Candy S Hwang
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0744, USA
| | - Liang Xu
- Department of Cellular and Molecular Medicine, School of Medicine; Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California, San Diego, La Jolla, CA 92093-0625, USA
| | - Wei Wang
- Department of Cellular and Molecular Medicine, School of Medicine; Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California, San Diego, La Jolla, CA 92093-0625, USA
| | - Sébastien Ulrich
- Department of Chemistry, Stanford University, Stanford, CA 94305-5017, USA Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université Montpellier, ENSCM, Ecole Nationale Supérieure de Chimie de Montpellier, 8 Rue de l'Ecole Normale, 34296 Montpellier cedex 5, France
| | - Lu Zhang
- Department of Chemistry, Division of Biomedical Engineering, Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Jenny Chong
- Department of Cellular and Molecular Medicine, School of Medicine; Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California, San Diego, La Jolla, CA 92093-0625, USA
| | - Ji Hyun Shin
- Department of Cellular and Molecular Medicine, School of Medicine; Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California, San Diego, La Jolla, CA 92093-0625, USA
| | - Xuhui Huang
- Department of Chemistry, Division of Biomedical Engineering, Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Eric T Kool
- Department of Chemistry, Stanford University, Stanford, CA 94305-5017, USA
| | - Charles E McKenna
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0744, USA
| | - Dong Wang
- Department of Cellular and Molecular Medicine, School of Medicine; Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California, San Diego, La Jolla, CA 92093-0625, USA
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13
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Malinen AM, Turtola M, Belogurov GA. Monitoring translocation of multisubunit RNA polymerase along the DNA with fluorescent base analogues. Methods Mol Biol 2015; 1276:31-51. [PMID: 25665557 DOI: 10.1007/978-1-4939-2392-2_3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Here we describe a direct fluorescence method that reports real-time occupancies of the pre- and post-translocated state of multisubunit RNA polymerase. In a stopped-flow setup, this method is capable of resolving a single base-pair translocation motion of RNA polymerase in real time. In a conventional spectrofluorometer, this method can be employed for studies of the time-averaged distribution of RNA polymerase on the DNA template. This method utilizes commercially available base analogue fluorophores integrated into template DNA strand in place of natural bases. We describe two template DNA strand designs where translocation of RNA polymerase from a pre-translocation to a post-translocation state results in disruption of stacking interactions of fluorophore with neighboring bases, with a concomitant large increase in fluorescence intensity.
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Affiliation(s)
- Anssi M Malinen
- Department of Biochemistry, University of Turku, Vatselankatu2, Arcanum, 3rd Floor, Turku, 20014, Finland
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14
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Imashimizu M, Shimamoto N, Oshima T, Kashlev M. Transcription elongation. Heterogeneous tracking of RNA polymerase and its biological implications. Transcription 2015; 5:e28285. [PMID: 25764114 PMCID: PMC4214235 DOI: 10.4161/trns.28285] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Regulation of transcription elongation via pausing of RNA polymerase has multiple physiological roles. The pausing mechanism depends on the sequence heterogeneity of the DNA being transcribed, as well as on certain interactions of polymerase with specific DNA sequences. In order to describe the mechanism of regulation, we introduce the concept of heterogeneity into the previously proposed alternative models of elongation, power stroke and Brownian ratchet. We also discuss molecular origins and physiological significances of the heterogeneity.
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15
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Zhang L, Silva DA, Pardo-Avila F, Wang D, Huang X. Structural Model of RNA Polymerase II Elongation Complex with Complete Transcription Bubble Reveals NTP Entry Routes. PLoS Comput Biol 2015; 11:e1004354. [PMID: 26134169 PMCID: PMC4489626 DOI: 10.1371/journal.pcbi.1004354] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 05/22/2015] [Indexed: 12/27/2022] Open
Abstract
The RNA polymerase II (Pol II) is a eukaryotic enzyme that catalyzes the synthesis of the messenger RNA using a DNA template. Despite numerous biochemical and biophysical studies, it remains elusive whether the “secondary channel” is the only route for NTP to reach the active site of the enzyme or if the “main channel” could be an alternative. On this regard, crystallographic structures of Pol II have been extremely useful to understand the structural basis of transcription, however, the conformation of the unpaired non-template DNA part of the full transcription bubble (TB) is still unknown. Since diffusion routes of the nucleoside triphosphate (NTP) substrate through the main channel might overlap with the TB region, gaining structural information of the full TB is critical for a complete understanding of Pol II transcription process. In this study, we have built a structural model of Pol II with a complete transcription bubble based on multiple sources of existing structural data and used Molecular Dynamics (MD) simulations together with structural analysis to shed light on NTP entry pathways. Interestingly, we found that although both channels have enough space to allow NTP loading, the percentage of MD conformations containing enough space for NTP loading through the secondary channel is twice higher than that of the main channel. Further energetic study based on MD simulations with NTP loaded in the channels has revealed that the diffusion of the NTP through the main channel is greatly disfavored by electrostatic repulsion between the NTP and the highly negatively charged backbones of nucleotides in the non-template DNA strand. Taken together, our results suggest that the secondary channel is the major route for NTP entry during Pol II transcription. In eukaryotic cells, the RNA polymerase II (Pol II) is a central enzyme that reads the genetic information encoded in the DNA template to synthetize a messenger RNA. To perform its function, Pol II needs to have the substrate nucleoside triphosphate (NTP) diffuse into its deeply buried active site. Despite numerous efforts, the NTP entry routes remain elusive: NTP could diffuse only through the secondary channel, or also via the main channel. The structural information of the transcription bubble is essential to study this process, however, the unpaired non-template DNA of the transcription bubble is absent in the available X-ray crystal structures. In this regard, we have built a structural model of the Pol II elongation complex with reconstructed transcription bubble using existing experimental data. We then performed Molecular Dynamics (MD) simulations and applied structural analysis to study the routes of NTP diffusion. We found that sterically the probability of NTP loading through the secondary channel is more than twice that of the main channel. Further analysis of the non-bonded energetic contributions to NTP diffusion suggests that NTP diffusion through the main channel is greatly disfavored by the electrostatic repulsion between the substrate and negatively charged backbones of nucleotides in the non-template strand of the transcription bubble. Altogether, our findings suggest that the secondary channel is the more favorable NTP diffusion route for Pol II transcription elongation.
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Affiliation(s)
- Lu Zhang
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, Center for System Biology and Human Health, School of Science and IAS, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Daniel-Adriano Silva
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, Center for System Biology and Human Health, School of Science and IAS, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Fátima Pardo-Avila
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, Center for System Biology and Human Health, School of Science and IAS, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
| | - Dong Wang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, United States of America
| | - Xuhui Huang
- Department of Chemistry and State Key Laboratory of Molecular Neuroscience, Center for System Biology and Human Health, School of Science and IAS, The Hong Kong University of Science and Technology, Kowloon, Hong Kong
- * E-mail:
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16
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Abstract
Bacteria lack subcellular compartments and harbor a single RNA polymerase that synthesizes both structural and protein-coding RNAs, which are cotranscriptionally processed by distinct pathways. Nascent rRNAs fold into elaborate secondary structures and associate with ribosomal proteins, whereas nascent mRNAs are translated by ribosomes. During elongation, nucleic acid signals and regulatory proteins modulate concurrent RNA-processing events, instruct RNA polymerase where to pause and terminate transcription, or act as roadblocks to the moving enzyme. Communications among complexes that carry out transcription, translation, repair, and other cellular processes ensure timely execution of the gene expression program and survival under conditions of stress. This network is maintained by auxiliary proteins that act as bridges between RNA polymerase, ribosome, and repair enzymes, blurring boundaries between separate information-processing steps and making assignments of unique regulatory functions meaningless. Understanding the regulation of transcript elongation thus requires genome-wide approaches, which confirm known and reveal new regulatory connections.
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Affiliation(s)
| | - Irina Artsimovitch
- Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210;
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17
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Antonopoulos IH, Murayama Y, Warner BA, Sekine SI, Yokoyama S, Carey PR. Time-resolved Raman and polyacrylamide gel electrophoresis observations of nucleotide incorporation and misincorporation in RNA within a bacterial RNA polymerase crystal. Biochemistry 2015; 54:652-65. [PMID: 25584498 DOI: 10.1021/bi501166r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The bacterial RNA polymerase (RNAP) elongation complex (EC) is highly stable and is able to extend an RNA chain for thousands of nucleotides. Understanding the processive mechanism of nucleotide addition requires detailed structural and temporal data for the EC reaction. Here, a time-resolved Raman spectroscopic analysis is combined with polyacrylamide gel electrophoresis (PAGE) to monitor nucleotide addition in single crystals of the Thermus thermophilus EC (TthEC) RNAP. When the cognate base GTP, labeled with (13)C and (15)N (*GTP), is soaked into crystals of the TthEC, changes in the Raman spectra show evidence of nucleotide incorporation and product formation. The major change is the reduction of *GTP's triphosphate intensity. Nucleotide incorporation is confirmed by PAGE assays. Both Raman and PAGE methods have a time resolution of minutes. There is also Raman spectroscopic evidence of a second population of *GTP in the crystal that does not become covalently linked to the nascent RNA chain. When this population is removed by "soaking out" (placing the crystal in a solution that contains no NTP), there are no perturbations to the Raman difference spectra, indicating that conformational changes are not detected in the EC. In contrast, the misincorporation of the noncognate base, (13)C- and (15)N-labeled UTP (*UTP), gives rise to large spectroscopic changes. As in the GTP experiment, reduction of the triphosphate relative intensity in the Raman soak-in data shows that the incorporation reaction occurs during the first few minutes of our instrumental dead time. This is also confirmed by PAGE analysis. Whereas PAGE data show *GTP converts 100% of the nascent RNA 14mer to 15mer, the noncognate *UTP converts only ∼50%. During *UTP soak-in, there is a slow, reversible formation of an α-helical amide I band in the Raman difference spectra peaking at 40 min. Similar to *GTP soak-in, *UTP soak-in shows Raman spectoscopic evidence of a second noncovalently bound *UTP population in the crystal. Moreover, the second population has a marked effect on the complex's conformational states because removing it by "soaking-out" unreacted *UTP causes large changes in protein and nucleic acid Raman marker bands in the time range of 10-100 min. The conformational changes observed for noncognate *UTP may indicate that the enzyme is preparing for proofreading to excise the misincorporated base. This idea is supported by the PAGE results for *UTP soak-out that show endonuclease activity is occurring.
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Affiliation(s)
- Ioanna H Antonopoulos
- Department of Biochemistry, Case Western Reserve University School of Medicine , Cleveland, Ohio 44106, United States
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18
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Yu J, Da LT, Huang X. Constructing kinetic models to elucidate structural dynamics of a complete RNA polymerase II elongation cycle. Phys Biol 2014; 12:016004. [DOI: 10.1088/1478-3975/12/1/016004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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19
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Windgassen TA, Mooney RA, Nayak D, Palangat M, Zhang J, Landick R. Trigger-helix folding pathway and SI3 mediate catalysis and hairpin-stabilized pausing by Escherichia coli RNA polymerase. Nucleic Acids Res 2014; 42:12707-21. [PMID: 25336618 PMCID: PMC4227799 DOI: 10.1093/nar/gku997] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The conformational dynamics of the polymorphous trigger loop (TL) in RNA polymerase (RNAP) underlie multiple steps in the nucleotide addition cycle and diverse regulatory mechanisms. These mechanisms include nascent RNA hairpin-stabilized pausing, which inhibits TL folding into the trigger helices (TH) required for rapid nucleotide addition. The nascent RNA pause hairpin forms in the RNA exit channel and promotes opening of the RNAP clamp domain, which in turn stabilizes a partially folded, paused TL conformation that disfavors TH formation. We report that inhibiting TH unfolding with a disulfide crosslink slowed multiround nucleotide addition only modestly but eliminated hairpin-stabilized pausing. Conversely, a substitution that disrupts the TH folding pathway and uncouples establishment of key TH–NTP contacts from complete TH formation and clamp movement allowed rapid catalysis and eliminated hairpin-stabilized pausing. We also report that the active-site distal arm of the TH aids TL folding, but that a 188-aa insertion in the Escherichia coli TL (sequence insertion 3; SI3) disfavors TH formation and stimulates pausing. The effect of SI3 depends on the jaw domain, but not on downstream duplex DNA. Our results support the view that both SI3 and the pause hairpin modulate TL folding in a constrained pathway of intermediate states.
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Affiliation(s)
- Tricia A Windgassen
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Rachel Anne Mooney
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Dhananjaya Nayak
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Murali Palangat
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jinwei Zhang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
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20
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Imashimizu M, Kashlev M. Unveiling translocation intermediates of RNA polymerase. Proc Natl Acad Sci U S A 2014; 111:7507-8. [PMID: 24828529 PMCID: PMC4040548 DOI: 10.1073/pnas.1406413111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Masahiko Imashimizu
- Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702
| | - Mikhail Kashlev
- Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702
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21
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Coliphage HK022 Nun protein inhibits RNA polymerase translocation. Proc Natl Acad Sci U S A 2014; 111:E2368-75. [PMID: 24853501 DOI: 10.1073/pnas.1319740111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Nun protein of coliphage HK022 arrests RNA polymerase (RNAP) in vivo and in vitro at pause sites distal to phage λ N-Utilization (nut) site RNA sequences. We tested the activity of Nun on ternary elongation complexes (TECs) assembled with templates lacking the λ nut sequence. We report that Nun stabilizes both translocation states of RNAP by restricting lateral movement of TEC along the DNA register. When Nun stabilized TEC in a pretranslocated register, immediately after NMP incorporation, it prevented binding of the next NTP and stimulated pyrophosphorolysis of the nascent transcript. In contrast, stabilization of TEC by Nun in a posttranslocated register allowed NTP binding and nucleotidyl transfer but inhibited pyrophosphorolysis and the next round of forward translocation. Nun binding to and action on the TEC requires a 9-bp RNA-DNA hybrid. We observed a Nun-dependent toe print upstream to the TEC. In addition, mutations in the RNAP β' subunit near the upstream end of the transcription bubble suppress Nun binding and arrest. These results suggest that Nun interacts with RNAP near the 5' edge of the RNA-DNA hybrid. By stabilizing translocation states through restriction of TEC lateral mobility, Nun represents a novel class of transcription arrest factors.
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22
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Dangkulwanich M, Ishibashi T, Bintu L, Bustamante C. Molecular mechanisms of transcription through single-molecule experiments. Chem Rev 2014; 114:3203-23. [PMID: 24502198 PMCID: PMC3983126 DOI: 10.1021/cr400730x] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Indexed: 01/02/2023]
Affiliation(s)
- Manchuta Dangkulwanich
- Jason L. Choy Laboratory of Single-Molecule
Biophysics, Department of Chemistry, California Institute
for Quantitative Biosciences, Department of Physics, and Department of Molecular and Cell
Biology, Howard Hughes Medical Institute,
and Kavli Energy NanoSciences Institute, University of California,
Berkeley, Berkeley, California 94720, United States
| | - Toyotaka Ishibashi
- Jason L. Choy Laboratory of Single-Molecule
Biophysics, Department of Chemistry, California Institute
for Quantitative Biosciences, Department of Physics, and Department of Molecular and Cell
Biology, Howard Hughes Medical Institute,
and Kavli Energy NanoSciences Institute, University of California,
Berkeley, Berkeley, California 94720, United States
- Division
of Life Science, Hong Kong University of
Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR
| | - Lacramioara Bintu
- Jason L. Choy Laboratory of Single-Molecule
Biophysics, Department of Chemistry, California Institute
for Quantitative Biosciences, Department of Physics, and Department of Molecular and Cell
Biology, Howard Hughes Medical Institute,
and Kavli Energy NanoSciences Institute, University of California,
Berkeley, Berkeley, California 94720, United States
- Department
of Bioengineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - Carlos Bustamante
- Jason L. Choy Laboratory of Single-Molecule
Biophysics, Department of Chemistry, California Institute
for Quantitative Biosciences, Department of Physics, and Department of Molecular and Cell
Biology, Howard Hughes Medical Institute,
and Kavli Energy NanoSciences Institute, University of California,
Berkeley, Berkeley, California 94720, United States
- Physical
Biosciences Division, Lawrence Berkeley
National Laboratory, Berkeley, California 94720, United States
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23
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Affiliation(s)
- David D Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
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24
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Kolb KE, Hein PP, Landick R. Antisense oligonucleotide-stimulated transcriptional pausing reveals RNA exit channel specificity of RNA polymerase and mechanistic contributions of NusA and RfaH. J Biol Chem 2013; 289:1151-63. [PMID: 24275665 DOI: 10.1074/jbc.m113.521393] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcript elongation by bacterial RNA polymerase (RNAP) is thought to be regulated at pause sites by open versus closed positions of the RNAP clamp domain, pause-suppressing regulators like NusG and RfaH that stabilize the closed-clampRNAP conformation, and pause-enhancing regulators like NusA and exit channel nascent RNA structures that stabilize the open clamp RNAP conformation. However, the mutual effects of these protein and RNA regulators on RNAP conformation are incompletely understood. For example, it is unknown whether NusA directly interacts with exit channel duplexes and whether formation of exit channel duplexes and RfaH binding compete by favoring the open and closed RNAP conformations. We report new insights into these mechanisms using antisense oligonucleotide mimics of a pause RNA hairpin from the leader region of the his biosynthetic operon of enteric bacteria like Escherichia coli. By systematically varying the structure and length of the oligonucleotide mimic, we determined that full pause stabilization requires an RNA-RNA duplex of at least 8 bp or a DNA-RNA duplex of at least 11 bp; RNA-RNA duplexes were more effective than DNA-RNA. NusA stimulation of pausing was optimal with 10-bp RNA-RNA duplexes and was aided by single-stranded RNA upstream of the duplex but was significantly reduced with DNA-RNA duplexes. Our results favor direct NusA stabilization of exit channel duplexes, which consequently affect RNAP clamp conformation. Effects of RfaH, which suppresses oligo-stabilization of pausing, were competitive with antisense oligonucleotide concentration, suggesting that RfaH and exit channel duplexes compete via opposing effects on RNAP clamp conformation.
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25
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Wang B, Feig M, Cukier RI, Burton ZF. Computational simulation strategies for analysis of multisubunit RNA polymerases. Chem Rev 2013; 113:8546-66. [PMID: 23987500 PMCID: PMC3829680 DOI: 10.1021/cr400046x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Indexed: 12/13/2022]
Affiliation(s)
- Beibei Wang
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824-1319, United States
| | - Michael Feig
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824-1319, United States
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Robert I. Cukier
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Zachary F. Burton
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824-1319, United States
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26
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Dangkulwanich M, Ishibashi T, Liu S, Kireeva ML, Lubkowska L, Kashlev M, Bustamante CJ. Complete dissection of transcription elongation reveals slow translocation of RNA polymerase II in a linear ratchet mechanism. eLife 2013; 2:e00971. [PMID: 24066225 PMCID: PMC3778554 DOI: 10.7554/elife.00971] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/13/2013] [Indexed: 12/31/2022] Open
Abstract
During transcription elongation, RNA polymerase has been assumed to attain equilibrium between pre- and post-translocated states rapidly relative to the subsequent catalysis. Under this assumption, recent single-molecule studies proposed a branched Brownian ratchet mechanism that necessitates a putative secondary nucleotide binding site on the enzyme. By challenging individual yeast RNA polymerase II with a nucleosomal barrier, we separately measured the forward and reverse translocation rates. Surprisingly, we found that the forward translocation rate is comparable to the catalysis rate. This finding reveals a linear, non-branched ratchet mechanism for the nucleotide addition cycle in which translocation is one of the rate-limiting steps. We further determined all the major on- and off-pathway kinetic parameters in the elongation cycle. The resulting translocation energy landscape shows that the off-pathway states are favored thermodynamically but not kinetically over the on-pathway states, conferring the enzyme its propensity to pause and furnishing the physical basis for transcriptional regulation. DOI:http://dx.doi.org/10.7554/eLife.00971.001.
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Affiliation(s)
- Manchuta Dangkulwanich
- Jason L Choy Laboratory of Single-Molecule Biophysics , University of California, Berkeley , Berkeley , United States ; Department of Chemistry , University of California, Berkeley , Berkeley , United States
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27
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Affiliation(s)
- Robert O J Weinzierl
- Department of Life Sciences, Division of Biomolecular Sciences, Imperial College London , Sir Alexander Fleming Building, Exhibition Road, London SW7 2AZ, United Kingdom
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28
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Nedialkov YA, Opron K, Assaf F, Artsimovitch I, Kireeva ML, Kashlev M, Cukier RI, Nudler E, Burton ZF. The RNA polymerase bridge helix YFI motif in catalysis, fidelity and translocation. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1829:187-98. [PMID: 23202476 PMCID: PMC3619131 DOI: 10.1016/j.bbagrm.2012.11.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 11/14/2012] [Accepted: 11/17/2012] [Indexed: 01/22/2023]
Abstract
The bridge α-helix in the β' subunit of RNA polymerase (RNAP) borders the active site and may have roles in catalysis and translocation. In Escherichia coli RNAP, a bulky hydrophobic segment near the N-terminal end of the bridge helix is identified (β' 772-YFI-774; the YFI motif). YFI is located at a distance from the active center and adjacent to a glycine hinge (β' 778-GARKG-782) involved in dynamic bending of the bridge helix. Remarkably, amino acid substitutions in YFI significantly alter intrinsic termination, pausing, fidelity and translocation of RNAP. F773V RNAP largely ignores the λ tR2 terminator at 200μM NTPs and is strongly reduced in λ tR2 recognition at 1μM NTPs. F773V alters RNAP pausing and backtracking and favors misincorporation. By contrast, the adjacent Y772A substitution increases fidelity and exhibits other transcriptional defects generally opposite to those of F773V. All atom molecular dynamics simulation revealed two separate functional connections emanating from YFI explaining the distinct effects of substitutions: Y772 communicates with the active site through the link domain in the β subunit, whereas F773 communicates through the fork domain in the β subunit. I774 interacts with the F-loop, which also contacts the glycine hinge of the bridge helix. These results identified negative and positive circuits coupled at YFI and employed for regulation of catalysis, elongation, termination and translocation.
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Affiliation(s)
- Yuri A. Nedialkov
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI 48824-1319, USA
- Department of Biochemistry, New York University Medical Center, New York, NY 10016, USA
| | - Kristopher Opron
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI 48824-1319, USA
| | - Fadi Assaf
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI 48824-1319, USA
| | - Irina Artsimovitch
- Department of Microbiology, The Ohio State University, Columbus, Ohio USA
| | - Maria L. Kireeva
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Mikhail Kashlev
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Robert I. Cukier
- Department of Chemistry, Michigan State University, E. Lansing, MI 48824-1319, USA
| | - Evgeny Nudler
- Department of Biochemistry, New York University Medical Center, New York, NY 10016, USA
| | - Zachary F. Burton
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI 48824-1319, USA
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29
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Intrinsic translocation barrier as an initial step in pausing by RNA polymerase II. J Mol Biol 2012; 425:697-712. [PMID: 23238253 DOI: 10.1016/j.jmb.2012.12.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 11/30/2012] [Accepted: 12/01/2012] [Indexed: 11/21/2022]
Abstract
Pausing of RNA polymerase II (RNAP II) by backtracking on DNA is a major regulatory mechanism in control of eukaryotic transcription. Backtracking occurs by extrusion of the 3' end of the RNA from the active center after bond formation and before translocation of RNAP II on DNA. In several documented cases, backtracking requires a special signal such as A/T-rich sequences forming an unstable RNA-DNA hybrid in the elongation complex. However, other sequence-dependent backtracking signals and conformations of RNAP II leading to backtracking remain unknown. Here, we demonstrate with S. cerevisiae RNAP II that a cleavage-deficient elongation factor TFIIS (TFIIS(AA)) enhances backtracked pauses during regular transcription. This is due to increased efficiency of formation of an intermediate that leads to backtracking. This intermediate may involve misalignment at the 3' end of the nascent RNA in the active center of the yeast RNAP II, and TFIIS(AA) promotes formation of this intermediate at the DNA sequences, presenting a high-energy barrier to translocation. We proposed a three-step mechanism for RNAP II pausing in which a prolonged dwell time in the pre-translocated state increases the likelihood of the 3' RNA end misalignment facilitating a backtrack pausing. These results demonstrate an important role of the intrinsic blocks to forward translocation in pausing by RNAP II.
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30
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Palangat M, Larson MH, Hu X, Gnatt A, Block SM, Landick R. Efficient reconstitution of transcription elongation complexes for single-molecule studies of eukaryotic RNA polymerase II. Transcription 2012; 3:146-53. [PMID: 22771949 DOI: 10.4161/trns.20269] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Single-molecule studies of RNA polymerase II (RNAP II) require high yields of transcription elongation complexes (TECs) with long DNA tethers upstream and downstream of the TEC. Here we report on a robust system to reconstitute both yeast and mammalian RNAP II with an efficiency of ~80% into TECs that elongate with an efficiency of ~90%, followed by rapid, high-efficiency tripartite ligation of long DNA fragments upstream and downstream of the reconstituted TECs. Single mammalian and yeast TECs reconstituted with this method have been successfully used in an optical-trapping transcription assay capable of applying forces that either assist or hinder transcript elongation.
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Affiliation(s)
- Murali Palangat
- Laboratory of Receptor Biology and Gene Expression, NCI, Bethesda, MD, USA.
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31
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Martinez-Rucobo FW, Cramer P. Structural basis of transcription elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:9-19. [PMID: 22982352 DOI: 10.1016/j.bbagrm.2012.09.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/06/2012] [Accepted: 09/07/2012] [Indexed: 01/13/2023]
Abstract
For transcription elongation, all cellular RNA polymerases form a stable elongation complex (EC) with the DNA template and the RNA transcript. Since the millennium, a wealth of structural information and complementary functional studies provided a detailed three-dimensional picture of the EC and many of its functional states. Here we summarize these studies that elucidated EC structure and maintenance, nucleotide selection and addition, translocation, elongation inhibition, pausing and proofreading, backtracking, arrest and reactivation, processivity, DNA lesion-induced stalling, lesion bypass, and transcriptional mutagenesis. In the future, additional structural and functional studies of elongation factors that control the EC and their possible allosteric modes of action should result in a more complete understanding of the dynamic molecular mechanisms underlying transcription elongation. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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32
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Zhou J, Schweikhard V, Block SM. Single-molecule studies of RNAPII elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:29-38. [PMID: 22982192 DOI: 10.1016/j.bbagrm.2012.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/27/2012] [Accepted: 08/29/2012] [Indexed: 01/22/2023]
Abstract
Elongation, the transcriptional phase in which RNA polymerase (RNAP) moves processively along a DNA template, occurs via a fundamental enzymatic mechanism that is thought to be universally conserved among multi-subunit polymerases in all kingdoms of life. Beyond this basic mechanism, a multitude of processes are integrated into transcript elongation, among them fidelity control, gene regulatory interactions involving elongation factors, RNA splicing or processing factors, and regulatory mechanisms associated with chromatin structure. Many kinetic and molecular details of the mechanism of the nucleotide addition cycle and its regulation, however, remain elusive and generate continued interest and even controversy. Recently, single-molecule approaches have emerged as powerful tools for the study of transcription in eukaryotic organisms. Here, we review recent progress and discuss some of the unresolved questions and ongoing debates, while anticipating future developments in the field. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.
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Affiliation(s)
- Jing Zhou
- Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
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Nedialkov YA, Nudler E, Burton ZF. RNA polymerase stalls in a post-translocated register and can hyper-translocate. Transcription 2012; 3:260-9. [PMID: 23132506 PMCID: PMC3632624 DOI: 10.4161/trns.22307] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Exonuclease (Exo) III was used to probe translocation states of RNA polymerase (RNAP) ternary elongation complexes (TECs). Escherichia coli RNAP stalls primarily in a post-translocation register that makes relatively slow excursions to a hyper-translocated state or to a pre-translocated state. Tagetitoxin (TGT) strongly inhibits hyper-translocation and inhibits backtracking, so, as indicated by Exo III mapping, TGT appears to stabilize both the pre- and probably a partially post-translocation state of RNAP. Because the pre-translocated to post-translocated transition is slow at many template positions, these studies appear inconsistent with a model in which RNAP makes frequent and rapid (i.e., millisecond phase) oscillations between pre- and post-translocation states. Nine nucleotides (9-nt) and 10-nt TECs, and TECs with longer nascent RNAs, have distinct translocation properties consistent with a 9–10 nt RNA/DNA hybrid. RNAP mutant proteins in the bridge helix and trigger loop are identified that inhibit or stimulate forward and backward translocation.
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Affiliation(s)
- Yuri A Nedialkov
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
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Miropolskaya N, Nikiforov V, Klimasauskas S, Artsimovitch I, Kulbachinskiy A. Modulation of RNA polymerase activity through the trigger loop folding. Transcription 2012; 1:89-94. [PMID: 21326898 DOI: 10.4161/trns.1.2.12544] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 05/28/2010] [Accepted: 06/01/2010] [Indexed: 11/19/2022] Open
Abstract
Folding of the trigger loop of RNA polymerase promotes nucleotide addition through creating a closed, catalytically competent conformation of the active center. Here, we discuss the impact of adjacent RNA polymerase elements, including the F loop and the jaw domain, as well as external regulatory factors on the trigger loop folding and catalysis.
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Kireeva ML, Opron K, Seibold SA, Domecq C, Cukier RI, Coulombe B, Kashlev M, Burton ZF. Molecular dynamics and mutational analysis of the catalytic and translocation cycle of RNA polymerase. BMC BIOPHYSICS 2012; 5:11. [PMID: 22676913 PMCID: PMC3533926 DOI: 10.1186/2046-1682-5-11] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 06/07/2012] [Indexed: 11/10/2022]
Abstract
UNLABELLED BACKGROUND During elongation, multi-subunit RNA polymerases (RNAPs) cycle between phosphodiester bond formation and nucleic acid translocation. In the conformation associated with catalysis, the mobile "trigger loop" of the catalytic subunit closes on the nucleoside triphosphate (NTP) substrate. Closing of the trigger loop is expected to exclude water from the active site, and dehydration may contribute to catalysis and fidelity. In the absence of a NTP substrate in the active site, the trigger loop opens, which may enable translocation. Another notable structural element of the RNAP catalytic center is the "bridge helix" that separates the active site from downstream DNA. The bridge helix may participate in translocation by bending against the RNA/DNA hybrid to induce RNAP forward movement and to vacate the active site for the next NTP loading. The transition between catalytic and translocation conformations of RNAP is not evident from static crystallographic snapshots in which macromolecular motions may be restrained by crystal packing. RESULTS All atom molecular dynamics simulations of Thermus thermophilus (Tt) RNAP reveal flexible hinges, located within the two helices at the base of the trigger loop, and two glycine hinges clustered near the N-terminal end of the bridge helix. As simulation progresses, these hinges adopt distinct conformations in the closed and open trigger loop structures. A number of residues (described as "switch" residues) trade atomic contacts (ion pairs or hydrogen bonds) in response to changes in hinge orientation. In vivo phenotypes and in vitro activities rendered by mutations in the hinge and switch residues in Saccharomyces cerevisiae (Sc) RNAP II support the importance of conformational changes predicted from simulations in catalysis and translocation. During simulation, the elongation complex with an open trigger loop spontaneously translocates forward relative to the elongation complex with a closed trigger loop. CONCLUSIONS Switching between catalytic and translocating RNAP forms involves closing and opening of the trigger loop and long-range conformational changes in the atomic contacts of amino acid side chains, some located at a considerable distance from the trigger loop and active site. Trigger loop closing appears to support chemistry and the fidelity of RNA synthesis. Trigger loop opening and limited bridge helix bending appears to promote forward nucleic acid translocation.
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Affiliation(s)
- Maria L Kireeva
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Kristopher Opron
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI, 48824-1319, USA
| | - Steve A Seibold
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI, 48824-1319, USA
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
- Department of Chemistry, University of Saint Mary, Leavenworth, KS, 66048, USA
| | - Céline Domecq
- Gene Transcription and Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), 110, Avenue des Pins Ouest, Montréal, Québec, H2W 1R7, CANADA
| | - Robert I Cukier
- Department of Chemistry, Michigan State University, E. Lansing, MI, 48824, USA
| | - Benoit Coulombe
- Gene Transcription and Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), 110, Avenue des Pins Ouest, Montréal, Québec, H2W 1R7, CANADA
- Department of Biochemistry, Université de Montréal, Montréal, Québec, H3C 3J7, CANADA
| | - Mikhail Kashlev
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Zachary F Burton
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI, 48824-1319, USA
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Malinen AM, Turtola M, Parthiban M, Vainonen L, Johnson MS, Belogurov GA. Active site opening and closure control translocation of multisubunit RNA polymerase. Nucleic Acids Res 2012; 40:7442-51. [PMID: 22570421 PMCID: PMC3424550 DOI: 10.1093/nar/gks383] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multisubunit RNA polymerase (RNAP) is the central information-processing enzyme in all cellular life forms, yet its mechanism of translocation along the DNA molecule remains conjectural. Here, we report direct monitoring of bacterial RNAP translocation following the addition of a single nucleotide. Time-resolved measurements demonstrated that translocation is delayed relative to nucleotide incorporation and occurs shortly after or concurrently with pyrophosphate release. An investigation of translocation equilibrium suggested that the strength of interactions between RNA 3′ nucleotide and nucleophilic and substrate sites determines the translocation state of transcription elongation complexes, whereas active site opening and closure modulate the affinity of the substrate site, thereby favoring the post- and pre-translocated states, respectively. The RNAP translocation mechanism is exploited by the antibiotic tagetitoxin, which mimics pyrophosphate and induces backward translocation by closing the active site.
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Affiliation(s)
- Anssi M Malinen
- Department of Biochemistry and Food Chemistry, University of Turku, 20014, Turku, Finland
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Walmacq C, Cheung AC, Kireeva ML, Lubkowska L, Ye C, Gotte D, Strathern JN, Carell T, Cramer P, Kashlev M. Mechanism of translesion transcription by RNA polymerase II and its role in cellular resistance to DNA damage. Mol Cell 2012; 46:18-29. [PMID: 22405652 PMCID: PMC3329276 DOI: 10.1016/j.molcel.2012.02.006] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 11/28/2011] [Accepted: 02/10/2012] [Indexed: 11/19/2022]
Abstract
UV-induced cyclobutane pyrimidine dimers (CPDs) in the template DNA strand stall transcription elongation by RNA polymerase II (Pol II). If the nucleotide excision repair machinery does not promptly remove the CPDs, stalled Pol II creates a roadblock for DNA replication and subsequent rounds of transcription. Here we present evidence that Pol II has an intrinsic capacity for translesion synthesis (TLS) that enables bypass of the CPD with or without repair. Translesion synthesis depends on the trigger loop and bridge helix, the two flexible regions of the Pol II subunit Rpb1 that participate in substrate binding, catalysis, and translocation. Substitutions in Rpb1 that promote lesion bypass in vitro increase UV resistance in vivo, and substitutions that inhibit lesion bypass decrease cell survival after UV irradiation. Thus, translesion transcription becomes essential for cell survival upon accumulation of the unrepaired CPD lesions in genomic DNA.
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Affiliation(s)
- Celine Walmacq
- NCI Center for Cancer Research, Frederick, MD, 21702, USA
| | - Alan C.M. Cheung
- Gene Center and Department of Biochemistry, Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | | | | | - Chengcheng Ye
- NCI Center for Cancer Research, Frederick, MD, 21702, USA
| | - Deanna Gotte
- NCI Center for Cancer Research, Frederick, MD, 21702, USA
| | | | - Thomas Carell
- Department of Chemistry, Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Butenandt-Strasse 5-13, 81377 Munich, Germany
| | - Patrick Cramer
- Gene Center and Department of Biochemistry, Center for Integrated Protein Science CIPSM, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
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The Bridge Helix of RNA polymerase acts as a central nanomechanical switchboard for coordinating catalysis and substrate movement. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2012; 2011:608385. [PMID: 22312317 PMCID: PMC3270539 DOI: 10.1155/2011/608385] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 10/25/2011] [Indexed: 11/17/2022]
Abstract
The availability of in vitro assembly systems to produce recombinant archaeal RNA polymerases (RNAPs) offers one of the most powerful experimental tools for investigating the still relatively poorly understood molecular mechanisms underlying RNAP function. Over the last few years, we pioneered new robot-based high-throughput mutagenesis approaches to study structure/function relationships within various domains surrounding the catalytic center. The Bridge Helix domain, which appears in numerous X-ray structures as a 35-amino-acid-long alpha helix, coordinates the concerted movement of several other domains during catalysis through kinking of two discrete molecular hinges. Mutations affecting these kinking mechanisms have a direct effect on the specific catalytic activity of RNAP and can in some instances more than double it. Molecular dynamics simulations have established themselves as exceptionally useful for providing additional insights and detailed models to explain the underlying structural motions.
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Hein PP, Palangat M, Landick R. RNA transcript 3'-proximal sequence affects translocation bias of RNA polymerase. Biochemistry 2011; 50:7002-14. [PMID: 21739957 DOI: 10.1021/bi200437q] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Translocation of RNA polymerase on DNA is thought to involve oscillations between pretranslocated and posttranslocated states that are rectified by nucleotide addition or pyrophosphorolysis. The pretranslocated register is also a precursor to transcriptional pause states that mediate regulation of transcript elongation. However, the determinants of bias between the pretranslocated and posttranslocated states are incompletely understood. To investigate translocation bias in multisubunit RNA polymerases, we measured rates of pyrophosphorolysis, which occurs in the pretranslocated register, in minimal elongation complexes containing T. thermophilus or E. coli RNA polymerase. Our results suggest that the identity of RNA:DNA nucleotides in the active site are strong determinants of susceptibility to pyrophosphorolysis, and thus translocation bias, with the 3' RNA nucleotide favoring the pretranslocated state in the order U > C > A > G. The preference of 3' U vs G for the pretranslocated register appeared to be universal among both bacterial and eukaryotic RNA polymerases and was confirmed by exonuclease III footprinting of defined elongation complexes. However, the relationship of pyrophosphate concentration to the rate of pyrophosphorolysis of 3' U-containing versus 3' G-containing elongation complexes did not match predictions of a simple mechanism in which 3'-RNA seqeunce affects only translocation bias and pyrophosphate (PPi) binds only to the pretranslocated state.
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Affiliation(s)
- Pyae P Hein
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
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40
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Templated nucleoside triphosphate binding to a noncatalytic site on RNA polymerase regulates transcription. Proc Natl Acad Sci U S A 2011; 108:6079-84. [PMID: 21447716 DOI: 10.1073/pnas.1011274108] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The regulation of RNA synthesis by RNA polymerase (RNAP) is essential for proper gene expression. Crystal structures of RNAP reveal two channels: the main channel that contains the downstream DNA and a secondary channel that leads directly to the catalytic site. Although nucleoside triphosphates (NTPs) have been seen only in the catalytic site and the secondary channel in these structures, several models of transcription elongation, based on biochemical studies, propose that template-dependent binding of NTPs in the main channel regulates RNA synthesis. These models, however, remain controversial. We used transient state kinetics and a mutant of RNAP to investigate the role of the main channel in regulating nucleotide incorporation. Our data indicate that a NTP specific for the i + 2 template position can bind to a noncatalytic site and increase the rate of RNA synthesis and that the NTP bound to this site can be shuttled directly into the catalytic site. We also identify fork loop 2, which lies across from the downstream DNA, as a functional component of this site. Taken together, our data support the existence of a noncatalytic template-specific NTP binding site in the main channel that is involved in the regulation of nucleotide incorporation. NTP binding to this site could promote high-fidelity processive synthesis under a variety of environmental conditions and allow DNA sequence-mediated regulatory signals to be communicated to the active site.
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Weinzierl ROJ. The nucleotide addition cycle of RNA polymerase is controlled by two molecular hinges in the Bridge Helix domain. BMC Biol 2010; 8:134. [PMID: 21034443 PMCID: PMC2988716 DOI: 10.1186/1741-7007-8-134] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 10/29/2010] [Indexed: 01/24/2023] Open
Abstract
Background Cellular RNA polymerases (RNAPs) are complex molecular machines that combine catalysis with concerted conformational changes in the active center. Previous work showed that kinking of a hinge region near the C-terminus of the Bridge Helix (BH-HC) plays a critical role in controlling the catalytic rate. Results Here, new evidence for the existence of an additional hinge region in the amino-terminal portion of the Bridge Helix domain (BH-HN) is presented. The nanomechanical properties of BH-HN emerge as a direct consequence of the highly conserved primary amino acid sequence. Mutations that are predicted to influence its flexibility cause corresponding changes in the rate of the nucleotide addition cycle (NAC). BH-HN displays functional properties that are distinct from BH-HC, suggesting that conformational changes in the Bridge Helix control the NAC via two independent mechanisms. Conclusions The properties of two distinct molecular hinges in the Bridge Helix of RNAP determine the functional contribution of this domain to key stages of the NAC by coordinating conformational changes in surrounding domains.
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Pupov DV, Kulbachinskiy AV. Structural dynamics of the active center of multisubunit RNA polymerases during RNA synthesis and proofreading. Mol Biol 2010. [DOI: 10.1134/s0026893310040023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Seibold SA, Singh BN, Zhang C, Kireeva M, Domecq C, Bouchard A, Nazione AM, Feig M, Cukier RI, Coulombe B, Kashlev M, Hampsey M, Burton ZF. Conformational coupling, bridge helix dynamics and active site dehydration in catalysis by RNA polymerase. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2010; 1799:575-87. [PMID: 20478425 DOI: 10.1016/j.bbagrm.2010.05.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 04/21/2010] [Accepted: 05/07/2010] [Indexed: 01/22/2023]
Abstract
Molecular dynamics simulation of Thermus thermophilus (Tt) RNA polymerase (RNAP) in a catalytic conformation demonstrates that the active site dNMP-NTP base pair must be substantially dehydrated to support full active site closing and optimum conditions for phosphodiester bond synthesis. In silico mutant beta R428A RNAP, which was designed based on substitutions at the homologous position (Rpb2 R512) of Saccharomyces cerevisiae (Sc) RNAP II, was used as a reference structure to compare to Tt RNAP in simulations. Long range conformational coupling linking a dynamic segment of the bridge alpha-helix, the extended fork loop, the active site, and the trigger loop-trigger helix is apparent and adversely affected in beta R428A RNAP. Furthermore, bridge helix bending is detected in the catalytic structure, indicating that bridge helix dynamics may regulate phosphodiester bond synthesis as well as translocation. An active site "latch" assembly that includes a key trigger helix residue Tt beta' H1242 and highly conserved active site residues beta E445 and R557 appears to help regulate active site hydration/dehydration. The potential relevance of these observations in understanding RNAP and DNAP induced fit and fidelity is discussed.
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Affiliation(s)
- Steve A Seibold
- Department of Biochemistry and Molecular Biology, Michigan State University, E. Lansing, MI 48824-1319, USA
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