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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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2
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Blossey R, Schiessel H. Histone mark recognition controls nucleosome translocation via a kinetic proofreading mechanism: Confronting theory and high-throughput experiments. Phys Rev E 2019; 99:060401. [PMID: 31330635 DOI: 10.1103/physreve.99.060401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Indexed: 12/13/2022]
Abstract
Chromatin remodelers are multidomain enzymatic motor complexes that displace nucleosomes along DNA and hence "remodel chromatin structure," i.e., they dynamically reorganize nucleosome positions in both gene activation and gene repression. Recently, experimental insights from structural biology methods and remodeling assays have substantially advanced the understanding of these key chromatin components. Here we confront the kinetic proofreading scenario of chromatin remodeling, which proposes a mechanical link between histone residue modifications and the ATP-dependent action of remodelers, with recent experiments. We show that recent high-throughput data on nucleosome libraries assayed with remodelers from the Imitation Switch family are in accord with our earlier predictions of the kinetic proofreading scenario. We make suggestions for experimentally verifiable predictions of the kinetic proofreading scenarios for remodelers from other families.
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Affiliation(s)
- Ralf Blossey
- Université de Lille, CNRS, UMR8576 Unité de Glycobiologie Structurale et Fonctionnelle (UGSF), F-59000 Lille, France
| | - Helmut Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
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3
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Wilson MD, Renault L, Maskell DP, Ghoneim M, Pye VE, Nans A, Rueda DS, Cherepanov P, Costa A. Retroviral integration into nucleosomes through DNA looping and sliding along the histone octamer. Nat Commun 2019; 10:4189. [PMID: 31519882 PMCID: PMC6744463 DOI: 10.1038/s41467-019-12007-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 08/08/2019] [Indexed: 01/02/2023] Open
Abstract
Retroviral integrase can efficiently utilise nucleosomes for insertion of the reverse-transcribed viral DNA. In face of the structural constraints imposed by the nucleosomal structure, integrase gains access to the scissile phosphodiester bonds by lifting DNA off the histone octamer at the site of integration. To clarify the mechanism of DNA looping by integrase, we determined a 3.9 Å resolution structure of the prototype foamy virus intasome engaged with a nucleosome core particle. The structural data along with complementary single-molecule Förster resonance energy transfer measurements reveal twisting and sliding of the nucleosomal DNA arm proximal to the integration site. Sliding the nucleosomal DNA by approximately two base pairs along the histone octamer accommodates the necessary DNA lifting from the histone H2A-H2B subunits to allow engagement with the intasome. Thus, retroviral integration into nucleosomes involves the looping-and-sliding mechanism for nucleosomal DNA repositioning, bearing unexpected similarities to chromatin remodelers. Retroviral integrases catalyze the insertion of viral DNA into the host cell DNA and can use nucleosomes as substrates for integration. Here the authors present the 3.9 Å cryo-EM structure of prototype foamy virus integrase after strand transfer into nucleosomal DNA, which together with single-molecule FRET measurements provides evidence for a DNA looping and sliding mechanism of integrases.
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Affiliation(s)
- Marcus D Wilson
- Macromolecular Machines Laboratory, The Francis Crick Institute, NW1 1AT, London, UK.,Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK
| | - Ludovic Renault
- Macromolecular Machines Laboratory, The Francis Crick Institute, NW1 1AT, London, UK.,NeCEN, University of Leiden, 2333CC, Leiden, Netherlands
| | - Daniel P Maskell
- Chromatin structure and mobile DNA Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.,Faculty of Biological Sciences, Leeds, LS2 9JT, UK
| | - Mohamed Ghoneim
- Single Molecule Imaging Group, MRC London Institute for Medical Science, London, W12 0NN, UK.,Molecular Virology, Department of Medicine, Imperial College London, London, W12 0NN, UK
| | - Valerie E Pye
- Chromatin structure and mobile DNA Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
| | - Andrea Nans
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, NW1 1AT, UK
| | - David S Rueda
- Single Molecule Imaging Group, MRC London Institute for Medical Science, London, W12 0NN, UK. .,Molecular Virology, Department of Medicine, Imperial College London, London, W12 0NN, UK.
| | - Peter Cherepanov
- Chromatin structure and mobile DNA Laboratory, The Francis Crick Institute, London, NW1 1AT, UK. .,Department of Medicine, Imperial College London, St-Mary's Campus, Norfolk Place, London, W2 1PG, UK.
| | - Alessandro Costa
- Macromolecular Machines Laboratory, The Francis Crick Institute, NW1 1AT, London, UK.
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4
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Willhoft O, Ghoneim M, Lin CL, Chua EYD, Wilkinson M, Chaban Y, Ayala R, McCormack EA, Ocloo L, Rueda DS, Wigley DB. Structure and dynamics of the yeast SWR1-nucleosome complex. Science 2018; 362:362/6411/eaat7716. [PMID: 30309918 DOI: 10.1126/science.aat7716] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 08/08/2018] [Indexed: 12/31/2022]
Abstract
The yeast SWR1 complex exchanges histone H2A in nucleosomes with Htz1 (H2A.Z in humans). The cryo-electron microscopy structure of the SWR1 complex bound to a nucleosome at 3.6-angstrom resolution reveals details of the intricate interactions between components of the SWR1 complex and its nucleosome substrate. Interactions between the Swr1 motor domains and the DNA wrap at superhelical location 2 distort the DNA, causing a bulge with concomitant translocation of the DNA by one base pair, coupled to conformational changes of the histone core. Furthermore, partial unwrapping of the DNA from the histone core takes place upon binding of nucleosomes to SWR1 complex. The unwrapping, as monitored by single-molecule data, is stabilized and has its dynamics altered by adenosine triphosphate binding but does not require hydrolysis.
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Affiliation(s)
- Oliver Willhoft
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Mohamed Ghoneim
- Single Molecule Imaging Group, MRC London Institute of Medical Sciences, London W12 0NN, UK.,Molecular Virology, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Chia-Liang Lin
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Eugene Y D Chua
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Martin Wilkinson
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Yuriy Chaban
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Rafael Ayala
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Elizabeth A McCormack
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Lorraine Ocloo
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - David S Rueda
- Single Molecule Imaging Group, MRC London Institute of Medical Sciences, London W12 0NN, UK. .,Molecular Virology, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Dale B Wigley
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK.
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5
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Blossey R, Schiessel H. The Latest Twists in Chromatin Remodeling. Biophys J 2018; 114:2255-2261. [PMID: 29310890 DOI: 10.1016/j.bpj.2017.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/09/2017] [Accepted: 12/12/2017] [Indexed: 02/03/2023] Open
Abstract
In its most restrictive interpretation, the notion of chromatin remodeling refers to the action of chromatin-remodeling enzymes on nucleosomes with the aim of displacing and removing them from the chromatin fiber (the effective polymer formed by a DNA molecule and proteins). This local modification of the fiber structure can have consequences for the initiation and repression of the transcription process, and when the remodeling process spreads along the fiber, it also results in long-range effects essential for fiber condensation. There are three regulatory levels of relevance that can be distinguished for this process: the intrinsic sequence preference of the histone octamer, which rules the positioning of the nucleosome along the DNA, notably in relation to the genetic information coded in DNA; the recognition or selection of nucleosomal substrates by remodeling complexes; and, finally, the motor action on the nucleosome exerted by the chromatin remodeler. Recent work has been able to provide crucial insights at each of these three levels that add new twists to this exciting and unfinished story, which we highlight in this perspective.
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Affiliation(s)
- Ralf Blossey
- University of Lille 1, Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR8576, Lille, France.
| | - Helmut Schiessel
- Institute Lorentz for Theoretical Physics, Leiden University, Leiden, the Netherlands
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Schilbach S, Hantsche M, Tegunov D, Dienemann C, Wigge C, Urlaub H, Cramer P. Structures of transcription pre-initiation complex with TFIIH and Mediator. Nature 2017; 551:204-209. [PMID: 29088706 PMCID: PMC6078178 DOI: 10.1038/nature24282] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 09/14/2017] [Indexed: 12/18/2022]
Abstract
For the initiation of transcription, RNA polymerase II (Pol II) assembles with general transcription factors on promoter DNA to form the pre-initiation complex (PIC). Here we report cryo-electron microscopy structures of the Saccharomyces cerevisiae PIC and PIC-core Mediator complex at nominal resolutions of 4.7 Å and 5.8 Å, respectively. The structures reveal transcription factor IIH (TFIIH), and suggest how the core and kinase TFIIH modules function in the opening of promoter DNA and the phosphorylation of Pol II, respectively. The TFIIH core subunit Ssl2 (a homologue of human XPB) is positioned on downstream DNA by the 'E-bridge' helix in TFIIE, consistent with TFIIE-stimulated DNA opening. The TFIIH kinase module subunit Tfb3 (MAT1 in human) anchors the kinase Kin28 (CDK7), which is mobile in the PIC but preferentially located between the Mediator hook and shoulder in the PIC-core Mediator complex. Open spaces between the Mediator head and middle modules may allow access of the kinase to its substrate, the C-terminal domain of Pol II.
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Affiliation(s)
- S Schilbach
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - M Hantsche
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - D Tegunov
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - C Dienemann
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - C Wigge
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - H Urlaub
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
- University Medical Center Göttingen, Institute of Clinical Chemistry, Bioanalytics Group, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - P Cramer
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
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Nucleosome-Chd1 structure and implications for chromatin remodelling. Nature 2017; 550:539-542. [PMID: 29019976 PMCID: PMC5697743 DOI: 10.1038/nature24046] [Citation(s) in RCA: 162] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/30/2017] [Indexed: 12/16/2022]
Abstract
Chromatin remodelling factors change nucleosome positioning and
facilitate DNA transcription, replication, and repair1. The conserved remodelling factor Chd12 can shift nucleosomes and induce a regular
nucleosome spacing3–5. Chd1 is required for RNA polymerase II
passage through nucleosomes6 and for
cellular pluripotency7. Chd1 contains the
DNA-binding domains SANT and SLIDE, a bilobal motor domain that hydrolyses
adenosine triphosphate (ATP), and a regulatory double chromodomain. Here we
report the cryo-electron microscopy (cryo-EM) structure of Chd1 from the yeast
S. cerevisiae bound to a nucleosome at a resolution of 4.8
Å. Chd1 detaches two turns of DNA from the histone octamer and binds
between the two DNA gyres in a state poised for catalysis. The SANT and SLIDE
domains contact detached DNA around superhelical location (SHL) -7 of the first
DNA gyre. The ATPase motor binds the second DNA gyre at SHL +2 and is anchored
to the N-terminal tail of histone H4 as in a recent nucleosome-Snf2 ATPase
structure8. Comparison with published
results9 reveals that the double
chromodomain swings towards nucleosomal DNA at SHL +1, resulting in ATPase
closure. The ATPase can then promote translocation of DNA towards the nucleosome
dyad, thereby loosening the first DNA gyre and remodelling the nucleosome.
Translocation may involve ratcheting of the two lobes of the ATPase, which is
trapped in a pre- or post-translocated state in the absence8 or presence, respectively, of transition state-mimicking
compounds.
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