1
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Herbine K, Nayak AR, Temiakov D. Structural basis for substrate binding and selection by human mitochondrial RNA polymerase. Nat Commun 2024; 15:7134. [PMID: 39164235 PMCID: PMC11335763 DOI: 10.1038/s41467-024-50817-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 07/22/2024] [Indexed: 08/22/2024] Open
Abstract
The mechanism by which RNAP selects cognate substrates and discriminates between deoxy and ribonucleotides is of fundamental importance to the fidelity of transcription. Here, we present cryo-EM structures of human mitochondrial transcription elongation complexes that reveal substrate ATP bound in Entry and Insertion Sites. In the Entry Site, the substrate binds along the O helix of the fingers domain of mtRNAP but does not interact with the templating DNA base. Interactions between RNAP and the triphosphate moiety of the NTP in the Entry Site ensure discrimination against nucleosides and their diphosphate and monophosphate derivatives but not against non-cognate rNTPs and dNTPs. Closing of the fingers domain over the catalytic site results in delivery of both the templating DNA base and the substrate into the Insertion Site and recruitment of the catalytic magnesium ions. The cryo-EM data also reveal a conformation adopted by mtRNAP to reject a non-cognate substrate from its active site. Our findings establish a structural basis for substrate binding and suggest a unified mechanism of NTP selection for single-subunit RNAPs.
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Affiliation(s)
- Karl Herbine
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Ashok R Nayak
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA
| | - Dmitry Temiakov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust St, Philadelphia, PA, 19107, USA.
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2
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Zhu Y, Vvedenskaya IO, Sze SH, Nickels BE, Kaplan CD. Quantitative analysis of transcription start site selection reveals control by DNA sequence, RNA polymerase II activity and NTP levels. Nat Struct Mol Biol 2024; 31:190-202. [PMID: 38177677 PMCID: PMC10928753 DOI: 10.1038/s41594-023-01171-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 11/03/2023] [Indexed: 01/06/2024]
Abstract
Transcription start site (TSS) selection is a key step in gene expression and occurs at many promoter positions over a wide range of efficiencies. Here we develop a massively parallel reporter assay to quantitatively dissect contributions of promoter sequence, nucleoside triphosphate substrate levels and RNA polymerase II (Pol II) activity to TSS selection by 'promoter scanning' in Saccharomyces cerevisiae (Pol II MAssively Systematic Transcript End Readout, 'Pol II MASTER'). Using Pol II MASTER, we measure the efficiency of Pol II initiation at 1,000,000 individual TSS sequences in a defined promoter context. Pol II MASTER confirms proposed critical qualities of S. cerevisiae TSS -8, -1 and +1 positions, quantitatively, in a controlled promoter context. Pol II MASTER extends quantitative analysis to surrounding sequences and determines that they tune initiation over a wide range of efficiencies. These results enabled the development of a predictive model for initiation efficiency based on sequence. We show that genetic perturbation of Pol II catalytic activity alters initiation efficiency mostly independently of TSS sequence, but selectively modulates preference for the initiating nucleotide. Intriguingly, we find that Pol II initiation efficiency is directly sensitive to guanosine-5'-triphosphate levels at the first five transcript positions and to cytosine-5'-triphosphate and uridine-5'-triphosphate levels at the second position genome wide. These results suggest individual nucleoside triphosphate levels can have transcript-specific effects on initiation, representing a cryptic layer of potential regulation at the level of Pol II biochemical properties. The results establish Pol II MASTER as a method for quantitative dissection of transcription initiation in eukaryotes.
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Affiliation(s)
- Yunye Zhu
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Irina O Vvedenskaya
- Department of Genetics and Waksman Institute, Rutgers University, Piscataway, NJ, USA
| | - Sing-Hoi Sze
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- Department of Computer Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Bryce E Nickels
- Department of Genetics and Waksman Institute, Rutgers University, Piscataway, NJ, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
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3
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Parise A, Ciardullo G, Prejanò M, Lande ADL, Marino T. On the Recognition of Natural Substrate CTP and Endogenous Inhibitor ddhCTP of SARS-CoV-2 RNA-Dependent RNA Polymerase: A Molecular Dynamics Study. J Chem Inf Model 2022; 62:4916-4927. [PMID: 36219674 DOI: 10.1021/acs.jcim.2c01002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The novel coronavirus SARS-CoV-2 is the causative agent of the COVID-19 outbreak that is affecting the entire planet. As the pandemic is still spreading worldwide, with multiple mutations of the virus, it is of interest and of help to employ computational methods for identifying potential inhibitors of the enzymes responsible for viral replication. Attractive antiviral nucleotide analogue RNA-dependent RNA polymerase (RdRp) chain terminator inhibitors are investigated with this purpose. This study, based on molecular dynamics (MD) simulations, addresses the important aspects of the incorporation of an endogenously synthesized nucleoside triphosphate, ddhCTP, in comparison with the natural nucleobase cytidine triphosphate (CTP) in RdRp. The ddhCTP species is the product of the viperin antiviral protein as part of the innate immune response. The absence of the ribose 3'-OH in ddhCTP could have important implications in its inhibitory mechanism of RdRp. We built an in silico model of the RNA strand embedded in RdRp using experimental methods, starting from the cryo-electron microscopy structure and exploiting the information obtained by spectrometry on the RNA sequence. We determined that the model was stable during the MD simulation time. The obtained results provide deeper insights into the incorporation of nucleoside triphosphates, whose molecular mechanism by the RdRp active site still remains elusive.
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Affiliation(s)
- Angela Parise
- Dipartimento di Chimica e Tecnologie Chimiche, Università Della Calabria, Via Pietro Bucci, 87036 Arcavacata di Rende, CS, Italy.,Université Paris-Saclay, CNRS, Institut de Chimie Physique UMR8000, Orsay 91405, France
| | - Giada Ciardullo
- Dipartimento di Chimica e Tecnologie Chimiche, Università Della Calabria, Via Pietro Bucci, 87036 Arcavacata di Rende, CS, Italy
| | - Mario Prejanò
- Dipartimento di Chimica e Tecnologie Chimiche, Università Della Calabria, Via Pietro Bucci, 87036 Arcavacata di Rende, CS, Italy
| | - Aurélien de la Lande
- Université Paris-Saclay, CNRS, Institut de Chimie Physique UMR8000, Orsay 91405, France
| | - Tiziana Marino
- Dipartimento di Chimica e Tecnologie Chimiche, Università Della Calabria, Via Pietro Bucci, 87036 Arcavacata di Rende, CS, Italy
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4
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Jones SP, Goossen C, Lewis SD, Delaney AM, Gleghorn ML. Not making the cut: Techniques to prevent RNA cleavage in structural studies of RNase-RNA complexes. J Struct Biol X 2022; 6:100066. [PMID: 35340590 PMCID: PMC8943300 DOI: 10.1016/j.yjsbx.2022.100066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 03/04/2022] [Indexed: 11/16/2022] Open
Abstract
RNases are varied in the RNA structures and sequences they target for cleavage and are an important type of enzyme in cells. Despite the numerous examples of RNases known, and of those with determined three-dimensional structures, relatively few examples exist with the RNase bound to intact cognate RNA substrate prior to cleavage. To better understand RNase structure and sequence specificity for RNA targets, in vitro methods used to assemble these enzyme complexes trapped in a pre-cleaved state have been developed for a number of different RNases. We have surveyed the Protein Data Bank for such structures and in this review detail methodologies that have successfully been used and relate them to the corresponding structures. We also offer ideas and suggestions for future method development. Many strategies within this review can be used in combination with X-ray crystallography, as well as cryo-EM, and other structure-solving techniques. Our hope is that this review will be used as a guide to resolve future yet-to-be-determined RNase-substrate complex structures.
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Affiliation(s)
- Seth P. Jones
- School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623-5603, United States
| | - Christian Goossen
- School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623-5603, United States
- Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Lothrop St, Pittsburgh, PA 15261, United States
| | - Sean D. Lewis
- School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623-5603, United States
- Mayo Clinic, 200 1st St SW, Rochester, MN 5590, United States
| | - Annie M. Delaney
- School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623-5603, United States
| | - Michael L. Gleghorn
- School of Chemistry and Materials Science, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623-5603, United States
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5
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Shin Y, Murakami KS. Watching the bacterial RNA polymerase transcription reaction by time-dependent soak-trigger-freeze X-ray crystallography. Enzymes 2021; 49:305-314. [PMID: 34696836 DOI: 10.1016/bs.enz.2021.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
RNA polymerase (RNAP) is the central enzyme of gene expression, which transcribes DNA to RNA. All cellular organisms synthesize RNA with highly conserved multi-subunit DNA-dependent RNAPs, except mitochondrial RNA transcription, which is carried out by a single-subunit RNAP. Over 60 years of extensive research has elucidated the structures and functions of cellular RNAPs. In this review, we introduce a brief structural feature of bacterial RNAP, the most well characterized model enzyme, and a novel experimental approach known as "Time-dependent soak-trigger-freeze X-ray crystallography" which can be used to observe the RNA synthesis reaction at atomic resolution in real time. This principle methodology can be used for elucidating fundamental mechanisms of cellular RNAP transcription.
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Affiliation(s)
- Yeonoh Shin
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, United States
| | - Katsuhiko S Murakami
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, United States.
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6
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Skalenko KS, Li L, Zhang Y, Vvedenskaya IO, Winkelman JT, Cope AL, Taylor DM, Shah P, Ebright RH, Kinney JB, Zhang Y, Nickels BE. Promoter-sequence determinants and structural basis of primer-dependent transcription initiation in Escherichia coli. Proc Natl Acad Sci U S A 2021; 118:e2106388118. [PMID: 34187896 PMCID: PMC8271711 DOI: 10.1073/pnas.2106388118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chemical modifications of RNA 5'-ends enable "epitranscriptomic" regulation, influencing multiple aspects of RNA fate. In transcription initiation, a large inventory of substrates compete with nucleoside triphosphates for use as initiating entities, providing an ab initio mechanism for altering the RNA 5'-end. In Escherichia coli cells, RNAs with a 5'-end hydroxyl are generated by use of dinucleotide RNAs as primers for transcription initiation, "primer-dependent initiation." Here, we use massively systematic transcript end readout (MASTER) to detect and quantify RNA 5'-ends generated by primer-dependent initiation for ∼410 (∼1,000,000) promoter sequences in E. coli The results show primer-dependent initiation in E. coli involves any of the 16 possible dinucleotide primers and depends on promoter sequences in, upstream, and downstream of the primer binding site. The results yield a consensus sequence for primer-dependent initiation, YTSS-2NTSS-1NTSSWTSS+1, where TSS is the transcription start site, NTSS-1NTSS is the primer binding site, Y is pyrimidine, and W is A or T. Biochemical and structure-determination studies show that the base pair (nontemplate-strand base:template-strand base) immediately upstream of the primer binding site (Y:RTSS-2, where R is purine) exerts its effect through the base on the DNA template strand (RTSS-2) through interchain base stacking with the RNA primer. Results from analysis of a large set of natural, chromosomally encoded Ecoli promoters support the conclusions from MASTER. Our findings provide a mechanistic and structural description of how TSS-region sequence hard-codes not only the TSS position but also the potential for epitranscriptomic regulation through primer-dependent transcription initiation.
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Affiliation(s)
- Kyle S Skalenko
- Department of Genetics, Rutgers University, Piscataway, NJ 08854
- Waksman Institute, Rutgers University, Piscataway, NJ 08854
| | - Lingting Li
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yuanchao Zhang
- Department of Biomedical and Health Informatics, The Children's Hospital of Philadelphia, Philadelphia, PA 19041
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Irina O Vvedenskaya
- Department of Genetics, Rutgers University, Piscataway, NJ 08854
- Waksman Institute, Rutgers University, Piscataway, NJ 08854
| | - Jared T Winkelman
- Department of Genetics, Rutgers University, Piscataway, NJ 08854
- Waksman Institute, Rutgers University, Piscataway, NJ 08854
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854
| | - Alexander L Cope
- Department of Genetics, Rutgers University, Piscataway, NJ 08854
| | - Deanne M Taylor
- Department of Biomedical and Health Informatics, The Children's Hospital of Philadelphia, Philadelphia, PA 19041
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Premal Shah
- Department of Genetics, Rutgers University, Piscataway, NJ 08854
| | - Richard H Ebright
- Waksman Institute, Rutgers University, Piscataway, NJ 08854
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854
| | - Justin B Kinney
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Bryce E Nickels
- Department of Genetics, Rutgers University, Piscataway, NJ 08854;
- Waksman Institute, Rutgers University, Piscataway, NJ 08854
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7
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Allosteric Activation of SARS-CoV-2 RNA-Dependent RNA Polymerase by Remdesivir Triphosphate and Other Phosphorylated Nucleotides. mBio 2021; 12:e0142321. [PMID: 34154407 PMCID: PMC8262916 DOI: 10.1128/mbio.01423-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The catalytic subunit of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA-dependent RNA polymerase (RdRp) Nsp12 has a unique nidovirus RdRp-associated nucleotidyltransferase (NiRAN) domain that transfers nucleoside monophosphates to the Nsp9 protein and the nascent RNA. The NiRAN and RdRp modules form a dynamic interface distant from their catalytic sites, and both activities are essential for viral replication. We report that codon-optimized (for the pause-free translation in bacterial cells) Nsp12 exists in an inactive state in which NiRAN-RdRp interactions are broken, whereas translation by slow ribosomes and incubation with accessory Nsp7/8 subunits or nucleoside triphosphates (NTPs) partially rescue RdRp activity. Our data show that adenosine and remdesivir triphosphates promote the synthesis of A-less RNAs, as does ppGpp, while amino acid substitutions at the NiRAN-RdRp interface augment activation, suggesting that ligand binding to the NiRAN catalytic site modulates RdRp activity. The existence of allosterically linked nucleotidyl transferase sites that utilize the same substrates has important implications for understanding the mechanism of SARS-CoV-2 replication and the design of its inhibitors.
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8
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Wang B, Svetlov V, Wolf YI, Koonin EV, Nudler E, Artsimovitch I. Allosteric activation of SARS-CoV-2 RdRp by remdesivir triphosphate and other phosphorylated nucleotides. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.01.24.428004. [PMID: 33948598 PMCID: PMC8095223 DOI: 10.1101/2021.01.24.428004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The catalytic subunit of SARS-CoV-2 RNA-dependent RNA polymerase (RdRp), Nsp12, has a unique NiRAN domain that transfers nucleoside monophosphates to the Nsp9 protein. The NiRAN and RdRp modules form a dynamic interface distant from their catalytic sites and both activities are essential for viral replication. We report that codon-optimized (for the pause-free translation) Nsp12 exists in inactive state in which NiRAN/RdRp interactions are broken, whereas translation by slow ribosomes and incubation with accessory Nsp7/8 subunits or NTPs partially rescue RdRp activity. Our data show that adenosine and remdesivir triphosphates promote synthesis of A-less RNAs, as does ppGpp, while amino acid substitutions at the NiRAN/RdRp interface augment activation, suggesting that ligand binding to the NiRAN catalytic site modulates RdRp activity. The existence of allosterically-linked nucleotidyl transferase sites that utilize the same substrates has important implications for understanding the mechanism of SARS-CoV-2 replication and design of its inhibitors. HIGHLIGHTS Codon-optimization of Nsp12 triggers misfolding and activity lossSlow translation, accessory Nsp7 and Nsp8 subunits, and NTPs rescue Nsp12Non-substrate nucleotides activate RNA chain synthesis, likely via NiRAN domainCrosstalk between two Nsp12 active sites that bind the same ligands.
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Affiliation(s)
- Bing Wang
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
- The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Vladimir Svetlov
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
- Howard Hughes Medical Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Irina Artsimovitch
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
- The Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
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9
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Yang H, Eremeeva E, Abramov M, Herdewijn P. The Network of Replication, Transcription, and Reverse Transcription of a Synthetic Genetic Cassette. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202011887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hui Yang
- Medicinal Chemistry Rega Institute for Medical Research KU Leuven Herestraat 49, Box-1041 3000 Leuven Belgium
| | - Elena Eremeeva
- Medicinal Chemistry Rega Institute for Medical Research KU Leuven Herestraat 49, Box-1041 3000 Leuven Belgium
| | - Mikhail Abramov
- Medicinal Chemistry Rega Institute for Medical Research KU Leuven Herestraat 49, Box-1041 3000 Leuven Belgium
| | - Piet Herdewijn
- Medicinal Chemistry Rega Institute for Medical Research KU Leuven Herestraat 49, Box-1041 3000 Leuven Belgium
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10
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Mäkinen JJ, Shin Y, Vieras E, Virta P, Metsä-Ketelä M, Murakami KS, Belogurov GA. The mechanism of the nucleo-sugar selection by multi-subunit RNA polymerases. Nat Commun 2021; 12:796. [PMID: 33542236 PMCID: PMC7862312 DOI: 10.1038/s41467-021-21005-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 01/06/2021] [Indexed: 01/18/2023] Open
Abstract
RNA polymerases (RNAPs) synthesize RNA from NTPs, whereas DNA polymerases synthesize DNA from 2'dNTPs. DNA polymerases select against NTPs by using steric gates to exclude the 2'OH, but RNAPs have to employ alternative selection strategies. In single-subunit RNAPs, a conserved Tyr residue discriminates against 2'dNTPs, whereas selectivity mechanisms of multi-subunit RNAPs remain hitherto unknown. Here, we show that a conserved Arg residue uses a two-pronged strategy to select against 2'dNTPs in multi-subunit RNAPs. The conserved Arg interacts with the 2'OH group to promote NTP binding, but selectively inhibits incorporation of 2'dNTPs by interacting with their 3'OH group to favor the catalytically-inert 2'-endo conformation of the deoxyribose moiety. This deformative action is an elegant example of an active selection against a substrate that is a substructure of the correct substrate. Our findings provide important insights into the evolutionary origins of biopolymers and the design of selective inhibitors of viral RNAPs.
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Affiliation(s)
- Janne J Mäkinen
- Department of Biochemistry, University of Turku, Turku, Finland
| | - Yeonoh Shin
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Eeva Vieras
- Department of Biochemistry, University of Turku, Turku, Finland
| | - Pasi Virta
- Department of Chemistry, University of Turku, Turku, Finland
| | | | - Katsuhiko S Murakami
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
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11
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Yang H, Eremeeva E, Abramov M, Herdewijn P. The Network of Replication, Transcription, and Reverse Transcription of a Synthetic Genetic Cassette. Angew Chem Int Ed Engl 2020; 60:4175-4182. [PMID: 33142013 DOI: 10.1002/anie.202011887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/27/2020] [Indexed: 11/07/2022]
Abstract
Synthetic nucleic acids, with four non-canonical nucleobases, can function as genetic materials. A comprehensive analysis of PCR amplification, transcription, reverse transcription, and cloning was done to screen for alternative genetic monomers. A small library of six modified nucleobases was selected: the modified 2'-deoxyribonucleoside (dZTPs) and ribonucleoside (rZTPs) triphosphates of 7-deaza-adenine, 5-chlorouracil, 7-deaza-guanine or inosine together with 5-fluorocytosine or 5-bromocytosine. The fragments composed of one to four modified nucleotides (denoted as DZA) have been successfully recognized and transcribed to natural or modified RNA (denoted as RZA) by T7 RNA polymerase. The fully modified RZA fragment could be reverse transcribed and then amplified in the presence of various dZTPs. Noticeably, modified fragments could function as genetic templates in vivo by encoding the 678 base pair gene of a fluorescent protein in bacteria. These results demonstrate the existence of a fully simulated genetic circuit that uses synthetic materials.
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Affiliation(s)
- Hui Yang
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, Box-1041, 3000, Leuven, Belgium
| | - Elena Eremeeva
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, Box-1041, 3000, Leuven, Belgium
| | - Mikhail Abramov
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, Box-1041, 3000, Leuven, Belgium
| | - Piet Herdewijn
- Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, Box-1041, 3000, Leuven, Belgium
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12
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Brandi A, Giangrossi M, Fabbretti A, Falconi M. The hns Gene of Escherichia coli Is Transcriptionally Down-Regulated by (p)ppGpp. Microorganisms 2020; 8:microorganisms8101558. [PMID: 33050410 PMCID: PMC7601328 DOI: 10.3390/microorganisms8101558] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 11/16/2022] Open
Abstract
Second messenger nucleotides, such as guanosine penta- or tetra-phosphate, commonly referred to as (p)ppGpp, are powerful signaling molecules, used by all bacteria to fine-tune cellular metabolism in response to nutrient availability. Indeed, under nutritional starvation, accumulation of (p)ppGpp reduces cell growth, inhibits stable RNAs synthesis, and selectively up- or down- regulates the expression of a large number of genes. Here, we show that the E. coli hns promoter responds to intracellular level of (p)ppGpp. hns encodes the DNA binding protein H-NS, one of the major components of bacterial nucleoid. Currently, H-NS is viewed as a global regulator of transcription in an environment-dependent mode. Combining results from relA (ppGpp synthetase) and spoT (ppGpp synthetase/hydrolase) null mutants with those from an inducible plasmid encoded RelA system, we have found that hns expression is inversely correlated with the intracellular concentration of (p)ppGpp, particularly in exponential phase of growth. Furthermore, we have reproduced in an in vitro system the observed in vivo (p)ppGpp-mediated transcriptional repression of hns promoter. Electrophoretic mobility shift assays clearly demonstrated that this unusual nucleotide negatively affects the stability of RNA polymerase-hns promoter complex. Hence, these findings demonstrate that the hns promoter is subjected to an RNA polymerase-mediated down-regulation by increased intracellular levels of (p)ppGpp.
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13
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Schaich MA, Sanford SL, Welfer GA, Johnson SA, Khoang TH, Opresko PL, Freudenthal BD. Mechanisms of nucleotide selection by telomerase. eLife 2020; 9:55438. [PMID: 32501800 PMCID: PMC7274783 DOI: 10.7554/elife.55438] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 05/18/2020] [Indexed: 01/31/2023] Open
Abstract
Telomerase extends telomere sequences at chromosomal ends to protect genomic DNA. During this process it must select the correct nucleotide from a pool of nucleotides with various sugars and base pairing properties, which is critically important for the proper capping of telomeric sequences by shelterin. Unfortunately, how telomerase selects correct nucleotides is unknown. Here, we determined structures of Tribolium castaneum telomerase reverse transcriptase (TERT) throughout its catalytic cycle and mapped the active site residues responsible for nucleoside selection, metal coordination, triphosphate binding, and RNA template stabilization. We found that TERT inserts a mismatch or ribonucleotide ~1 in 10,000 and ~1 in 14,000 insertion events, respectively. At biological ribonucleotide concentrations, these rates translate to ~40 ribonucleotides inserted per 10 kilobases. Human telomerase assays determined a conserved tyrosine steric gate regulates ribonucleotide insertion into telomeres. Cumulatively, our work provides insight into how telomerase selects the proper nucleotide to maintain telomere integrity.
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Affiliation(s)
- Matthew A Schaich
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, United States
| | - Samantha L Sanford
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, and UPMC Hillman Cancer Center, Pittsburgh, United States
| | - Griffin A Welfer
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, United States
| | - Samuel A Johnson
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, and UPMC Hillman Cancer Center, Pittsburgh, United States
| | - Thu H Khoang
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, United States
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, and UPMC Hillman Cancer Center, Pittsburgh, United States
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, United States.,Department of Cancer Biology, University of Kansas Medical Center, Kansas City, United States
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14
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Qiu C, Jin H, Vvedenskaya I, Llenas JA, Zhao T, Malik I, Visbisky AM, Schwartz SL, Cui P, Čabart P, Han KH, Lai WKM, Metz RP, Johnson CD, Sze SH, Pugh BF, Nickels BE, Kaplan CD. Universal promoter scanning by Pol II during transcription initiation in Saccharomyces cerevisiae. Genome Biol 2020; 21:132. [PMID: 32487207 PMCID: PMC7265651 DOI: 10.1186/s13059-020-02040-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 05/08/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The majority of eukaryotic promoters utilize multiple transcription start sites (TSSs). How multiple TSSs are specified at individual promoters across eukaryotes is not understood for most species. In Saccharomyces cerevisiae, a pre-initiation complex (PIC) comprised of Pol II and conserved general transcription factors (GTFs) assembles and opens DNA upstream of TSSs. Evidence from model promoters indicates that the PIC scans from upstream to downstream to identify TSSs. Prior results suggest that TSS distributions at promoters where scanning occurs shift in a polar fashion upon alteration in Pol II catalytic activity or GTF function. RESULTS To determine the extent of promoter scanning across promoter classes in S. cerevisiae, we perturb Pol II catalytic activity and GTF function and analyze their effects on TSS usage genome-wide. We find that alterations to Pol II, TFIIB, or TFIIF function widely alter the initiation landscape consistent with promoter scanning operating at all yeast promoters, regardless of promoter class. Promoter architecture, however, can determine the extent of promoter sensitivity to altered Pol II activity in ways that are predicted by a scanning model. CONCLUSIONS Our observations coupled with previous data validate key predictions of the scanning model for Pol II initiation in yeast, which we term the shooting gallery. In this model, Pol II catalytic activity and the rate and processivity of Pol II scanning together with promoter sequence determine the distribution of TSSs and their usage.
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Affiliation(s)
- Chenxi Qiu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA
- Present Address: Department of Medicine, Division of Translational Therapeutics, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Huiyan Jin
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA
| | - Irina Vvedenskaya
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ, 08854, USA
- Department of Genetics, Rutgers University, Piscataway, NJ, 08854, USA
| | - Jordi Abante Llenas
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, 77843-3128, USA
- Present Address: Whitaker Biomedical Engineering Institute, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Tingting Zhao
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Indranil Malik
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA
- Present Address: Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Alex M Visbisky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Scott L Schwartz
- Genomics and Bioinformatics Service, Texas A&M AgriLife, College Station, TX, 77845, USA
| | - Ping Cui
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA
| | - Pavel Čabart
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA
- Present Address: First Faculty of Medicine, Charles University, BIOCEV, 252 42, Vestec, Czech Republic
| | - Kang Hoo Han
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA, 16802, USA
| | - William K M Lai
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA, 16802, USA
- Present Address: Department of Molecular Biology and Genetics, 458 Biotechnology, Cornell University, New York, 14853, USA
| | - Richard P Metz
- Genomics and Bioinformatics Service, Texas A&M AgriLife, College Station, TX, 77845, USA
| | - Charles D Johnson
- Genomics and Bioinformatics Service, Texas A&M AgriLife, College Station, TX, 77845, USA
| | - Sing-Hoi Sze
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA
- Department of Computer Science and Engineering, Texas A&M University, College Station, TX, 77843-3127, USA
| | - B Franklin Pugh
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA, 16802, USA
- Present Address: Department of Molecular Biology and Genetics, 458 Biotechnology, Cornell University, New York, 14853, USA
| | - Bryce E Nickels
- Waksman Institute of Microbiology, Rutgers University, Piscataway, NJ, 08854, USA
- Department of Genetics, Rutgers University, Piscataway, NJ, 08854, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
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15
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Wang J, Alvin Chew BL, Lai Y, Dong H, Xu L, Balamkundu S, Cai WM, Cui L, Liu CF, Fu XY, Lin Z, Shi PY, Lu TK, Luo D, Jaffrey SR, Dedon PC. Quantifying the RNA cap epitranscriptome reveals novel caps in cellular and viral RNA. Nucleic Acids Res 2019; 47:e130. [PMID: 31504804 PMCID: PMC6847653 DOI: 10.1093/nar/gkz751] [Citation(s) in RCA: 105] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 07/16/2019] [Accepted: 08/23/2019] [Indexed: 12/13/2022] Open
Abstract
Chemical modification of transcripts with 5' caps occurs in all organisms. Here, we report a systems-level mass spectrometry-based technique, CapQuant, for quantitative analysis of an organism's cap epitranscriptome. The method was piloted with 21 canonical caps-m7GpppN, m7GpppNm, GpppN, GpppNm, and m2,2,7GpppG-and 5 'metabolite' caps-NAD, FAD, UDP-Glc, UDP-GlcNAc, and dpCoA. Applying CapQuant to RNA from purified dengue virus, Escherichia coli, yeast, mouse tissues, and human cells, we discovered new cap structures in humans and mice (FAD, UDP-Glc, UDP-GlcNAc, and m7Gpppm6A), cell- and tissue-specific variations in cap methylation, and high proportions of caps lacking 2'-O-methylation (m7Gpppm6A in mammals, m7GpppA in dengue virus). While substantial Dimroth-induced loss of m1A and m1Am arose with specific RNA processing conditions, human lymphoblast cells showed no detectable m1A or m1Am in caps. CapQuant accurately captured the preference for purine nucleotides at eukaryotic transcription start sites and the correlation between metabolite levels and metabolite caps.
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Affiliation(s)
- Jin Wang
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, Inner Mongolia University, Hohhot, People's Republic of China
- School of Life Sciences, Inner Mongolia University, Hohhot, People's Republic of China
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
| | - Bing Liang Alvin Chew
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
- NTU Institute of Health Technologies, Interdisciplinary Graduate Programme, Nanyang Technological University, Singapore
| | - Yong Lai
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
| | - Hongping Dong
- Shanghai Blueray Biopharma, Shanghai, People's Republic of China
| | - Luang Xu
- Cancer Science Institute of Singapore, Singapore
| | - Seetharamsingh Balamkundu
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Weiling Maggie Cai
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
- Department of Microbiology, National University of Singapore, Singapore
| | - Liang Cui
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
| | - Chuan Fa Liu
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Xin-Yuan Fu
- Cancer Science Institute of Singapore, Singapore
| | - Zhenguo Lin
- Department of Biology, Saint Louis University, St. Louis, MO, USA
| | - Pei-Yong Shi
- Departments of Biochemistry & Molecular Biology and Pharmacology & Toxicology, and Sealy Center for Structural Biology & Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Timothy K Lu
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
- Synthetic Biology Center, Departments of Biological Engineering and Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Dahai Luo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY, USA
| | - Peter C Dedon
- Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Singapore
- Dept. of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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16
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Lu Z, Lin Z. Pervasive and dynamic transcription initiation in Saccharomyces cerevisiae. Genome Res 2019; 29:1198-1210. [PMID: 31076411 PMCID: PMC6633255 DOI: 10.1101/gr.245456.118] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 05/07/2019] [Indexed: 12/15/2022]
Abstract
Transcription initiation is finely regulated to ensure proper expression and function of genes. The regulated transcription initiation in response to various environmental stimuli in a classic model organism Saccharomyces cerevisiae has not been systematically investigated. In this study, we generated quantitative maps of transcription start sites (TSSs) at a single-nucleotide resolution for S. cerevisiae grown in nine different conditions using no-amplification nontagging Cap analysis of gene expression (nAnT-iCAGE) sequencing. We mapped ∼1 million well-supported TSSs, suggesting highly pervasive transcription initiation in the compact genome of the budding yeast. The comprehensive TSS maps allowed us to identify core promoters for ∼96% verified protein-coding genes. We corrected misannotation of translation start codon for 122 genes and suggested an alternative start codon for 57 genes. We found that 56% of yeast genes are controlled by multiple core promoters, and alternative core promoter usage by a gene is widespread in response to changing environments. Most core promoter shifts are coupled with altered gene expression, indicating that alternative core promoter usage might play an important role in controlling gene transcriptional activities. Based on their activities in responding to environmental cues, we divided core promoters into constitutive class (55%) and inducible class (45%). The two classes of core promoters display distinctive patterns in transcriptional abundance, chromatin structure, promoter shape, and sequence context. In summary, our study improved the annotation of the yeast genome and demonstrated a much more pervasive and dynamic nature of transcription initiation in yeast than previously recognized.
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Affiliation(s)
- Zhaolian Lu
- Department of Biology, Saint Louis University, St. Louis, Missouri 63104, USA
| | - Zhenguo Lin
- Department of Biology, Saint Louis University, St. Louis, Missouri 63104, USA
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17
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Genome-wide effects on Escherichia coli transcription from ppGpp binding to its two sites on RNA polymerase. Proc Natl Acad Sci U S A 2019; 116:8310-8319. [PMID: 30971496 DOI: 10.1073/pnas.1819682116] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The second messenger nucleotide ppGpp dramatically alters gene expression in bacteria to adjust cellular metabolism to nutrient availability. ppGpp binds to two sites on RNA polymerase (RNAP) in Escherichia coli, but it has also been reported to bind to many other proteins. To determine the role of the RNAP binding sites in the genome-wide effects of ppGpp on transcription, we used RNA-seq to analyze transcripts produced in response to elevated ppGpp levels in strains with/without the ppGpp binding sites on RNAP. We examined RNAs rapidly after ppGpp production without an accompanying nutrient starvation. This procedure enriched for direct effects of ppGpp on RNAP rather than for indirect effects on transcription resulting from starvation-induced changes in metabolism or on secondary events from the initial effects on RNAP. The transcriptional responses of all 757 genes identified after 5 minutes of ppGpp induction depended on ppGpp binding to RNAP. Most (>75%) were not reported in earlier studies. The regulated transcripts encode products involved not only in translation but also in many other cellular processes. In vitro transcription analysis of more than 100 promoters from the in vivo dataset identified a large collection of directly regulated promoters, unambiguously demonstrated that most effects of ppGpp on transcription in vivo were direct, and allowed comparison of DNA sequences from inhibited, activated, and unaffected promoter classes. Our analysis greatly expands our understanding of the breadth of the stringent response and suggests promoter sequence features that contribute to the specific effects of ppGpp.
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18
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Schaich MA, Smith MR, Cloud AS, Holloran SM, Freudenthal BD. Structures of a DNA Polymerase Inserting Therapeutic Nucleotide Analogues. Chem Res Toxicol 2017; 30:1993-2001. [PMID: 28862449 PMCID: PMC6494084 DOI: 10.1021/acs.chemrestox.7b00173] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Members of the nucleoside analogue class of cancer therapeutics compete with canonical nucleotides to disrupt numerous cellular processes, including nucleotide homeostasis, DNA and RNA synthesis, and nucleotide metabolism. Nucleoside analogues are triphosphorylated and subsequently inserted into genomic DNA, contributing to the efficacy of therapeutic nucleosides in multiple ways. In some cases, the altered base acts as a mutagen, altering the DNA sequence to promote cellular death; in others, insertion of the altered nucleotide triggers DNA repair pathways, which produce lethal levels of cytotoxic intermediates such as single and double stranded DNA breaks. As a prerequisite to many of these biological outcomes, the modified nucleotide must be accommodated in the DNA polymerase active site during nucleotide insertion. Currently, the molecular contacts that mediate DNA polymerase insertion of modified nucleotides remain unknown for multiple therapeutic compounds, despite decades of clinical use. To determine how modified bases are inserted into duplex DNA, we used mammalian DNA polymerase β (pol β) to visualize the structural conformations of four therapeutically relevant modified nucleotides, 6-thio-2'-deoxyguanosine-5'-triphosphate (6-TdGTP), 5-fluoro-2'-deoxyuridine-5'-triphosphate (5-FdUTP), 5-formyl-deoxycytosine-5'-triphosphate (5-FodCTP), and 5-formyl-deoxyuridine-5'-triphosphate (5-FodUTP). Together, the structures reveal a pattern in which the modified nucleotides utilize Watson-Crick base pairing interactions similar to that of unmodified nucleotides. The nucleotide modifications were consistently positioned in the major groove of duplex DNA, accommodated by an open cavity in pol β. These results provide novel information for the rational design of new therapeutic nucleoside analogues and a greater understanding of how modified nucleotides are tolerated by polymerases.
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Affiliation(s)
| | | | | | | | - Bret D. Freudenthal
- Corresponding Author 4015 Wahl Hall West, Laboratory of Genome Maintenance and Structural Biology, Department of Biochemistry and Molecular Biology, and Department of Cancer Biology, University of Kansas Medical Center Kansas City, Kansas 66160. Phone: 913-588-5560,
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19
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Fouqueau T, Blombach F, Werner F. Evolutionary Origins of Two-Barrel RNA Polymerases and Site-Specific Transcription Initiation. Annu Rev Microbiol 2017; 71:331-348. [PMID: 28657884 DOI: 10.1146/annurev-micro-091014-104145] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Evolution-related multisubunit RNA polymerases (RNAPs) carry out RNA synthesis in all domains life. Although their catalytic cores and fundamental mechanisms of transcription elongation are conserved, the initiation stage of the transcription cycle differs substantially in bacteria, archaea, and eukaryotes in terms of the requirements for accessory factors and details of the molecular mechanisms. This review focuses on recent insights into the evolution of the transcription apparatus with regard to (a) the surprisingly pervasive double-Ψ β-barrel active-site configuration among different nucleic acid polymerase families, (b) the origin and phylogenetic distribution of TBP, TFB, and TFE transcription factors, and
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Affiliation(s)
- Thomas Fouqueau
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom; ,
| | - Fabian Blombach
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom; ,
| | - Finn Werner
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom; ,
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20
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Antonopoulos IH, Warner BA, Carey PR. Concerted Protein and Nucleic Acid Conformational Changes Observed Prior to Nucleotide Incorporation in a Bacterial RNA Polymerase: Raman Crystallographic Evidence. Biochemistry 2015. [PMID: 26222797 DOI: 10.1021/acs.biochem.5b00484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transcription elongation requires the continuous incorporation of ribonucleotide triphosphates into a growing transcript. RNA polymerases (RNAPs) are able to processively synthesize a growing RNA chain via translocation of the RNAP enzyme along its nucleic acid template strand after each nucleotide addition cycle. In this work, a time-resolved Raman spectroscopic analysis of nucleotide addition in single crystals of the Thermus thermophilus elongation complex (TthEC) is reported. When [(13)C,(15)N]GTP (*GTP) is soaked into crystals of the TthEC, large reversible changes in the Raman spectrum that are assigned to protein and nucleic acid conformational events during a single-nucleotide incorporation are observed. The *GTP population in the TthEC crystal reaches a stable population at 37 min, while substantial and reversible protein conformational changes (mainly ascribed to changes in α-helical Raman features) maximize at approximately 50 min. At the same time, changes in nucleic acid bases and phosphodiester backbone Raman marker bands occur. Catalysis begins at approximately 65-70 min, soon after the maximal protein and DNA changes, and is monitored via the decline in a triphosphate vibrational Raman mode from *GTP. The Raman data indicate that approximately 40% of the total triphosphate population, present as *GTP, reacts in the crystal. This may suggest that a second population of noncovalently bound *GTP resides in a site distinct from the catalytic site. The data reported here are an extension of our recent work on the elongation complex (EC) of a bacterial RNAP, Thermus thermophilus (Tth), where Raman spectroscopy and polyacrylamide gel electrophoresis were employed to monitor incorporation and misincorporation in single TthEC crystals [Antonopoulos, I. H., et al. (2015) Biochemistry 54, 652-665]. Therefore, the initial study establishes the groundwork for this study. In contrast to our previous study, in which incorporation takes place very rapidly inside the crystals, the data on this single crystal exhibit a slower time regime, which allows the dissection of the structural dynamics associated with GMP incorporation within the TthEC crystal.
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Affiliation(s)
- Ioanna H Antonopoulos
- Department of Biochemistry, Case Western Reserve University School of Medicine , Cleveland, Ohio 44106, United States
| | - Brittany A Warner
- Department of Biochemistry and Molecular Biology, The Center of RNA Molecular Biology, Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Paul R Carey
- Department of Biochemistry, Case Western Reserve University School of Medicine , Cleveland, Ohio 44106, United States
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21
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Lenneman BR, Rothman-Denes LB. Structural and biochemical investigation of bacteriophage N4-encoded RNA polymerases. Biomolecules 2015; 5:647-67. [PMID: 25924224 PMCID: PMC4496689 DOI: 10.3390/biom5020647] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/01/2015] [Accepted: 04/13/2015] [Indexed: 11/16/2022] Open
Abstract
Bacteriophage N4 regulates the temporal expression of its genome through the activity of three distinct RNA polymerases (RNAP). Expression of the early genes is carried out by a phage-encoded, virion-encapsidated RNAP (vRNAP) that is injected into the host at the onset of infection and transcribes the early genes. These encode the components of new transcriptional machinery (N4 RNAPII and cofactors) responsible for the synthesis of middle RNAs. Both N4 RNAPs belong to the T7-like "single-subunit" family of polymerases. Herein, we describe their mechanisms of promoter recognition, regulation, and roles in the phage life cycle.
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Affiliation(s)
- Bryan R Lenneman
- Committee on Genetics, Genomics, and Systems Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
| | - Lucia B Rothman-Denes
- Committee on Genetics, Genomics, and Systems Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
- Department of Molecular Genetics and Cell Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
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22
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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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23
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Relationships of RNA polymerase II genetic interactors to transcription start site usage defects and growth in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2014; 5:21-33. [PMID: 25380729 PMCID: PMC4291466 DOI: 10.1534/g3.114.015180] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Transcription initiation by RNA Polymerase II (Pol II) is an essential step in gene expression and regulation in all organisms. Initiation requires a great number of factors, and defects in this process can be apparent in the form of altered transcription start site (TSS) selection in Saccharomyces cerevisiae (Baker's yeast). It has been shown previously that TSS selection in S. cerevisiae is altered in Pol II catalytic mutants defective in a conserved active site feature known as the trigger loop. Pol II trigger loop mutants show growth phenotypes in vivo that correlate with biochemical defects in vitro and exhibit wide-ranging genetic interactions. We assessed how Pol II mutant growth phenotypes and TSS selection in vivo are modified by Pol II genetic interactors to estimate the relationship between altered TSS selection in vivo and organismal fitness of Pol II mutants. We examined whether the magnitude of TSS selection defects could be correlated with Pol II mutant-transcription factor double mutant phenotypes. We observed broad genetic interactions among Pol II trigger loop mutants and General Transcription Factor (GTF) alleles, with reduced-activity Pol II mutants especially sensitive to defects in TFIIB. However, Pol II mutant growth defects could be uncoupled from TSS selection defects in some Pol II allele-GTF allele double mutants, whereas a number of other Pol II genetic interactors did not influence ADH1 start site selection alone or in combination with Pol II mutants. Initiation defects are likely only partially responsible for Pol II allele growth phenotypes, with some Pol II genetic interactors able to exacerbate Pol II mutant growth defects while leaving initiation at a model TSS selection promoter unaffected.
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24
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Basu RS, Warner BA, Molodtsov V, Pupov D, Esyunina D, Fernández-Tornero C, Kulbachinskiy A, Murakami KS. Structural basis of transcription initiation by bacterial RNA polymerase holoenzyme. J Biol Chem 2014; 289:24549-59. [PMID: 24973216 DOI: 10.1074/jbc.m114.584037] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bacterial RNA polymerase (RNAP) holoenzyme containing σ factor initiates transcription at specific promoter sites by de novo RNA priming, the first step of RNA synthesis where RNAP accepts two initiating ribonucleoside triphosphates (iNTPs) and performs the first phosphodiester bond formation. We present the structure of de novo transcription initiation complex that reveals unique contacts of the iNTPs bound at the transcription start site with the template DNA and also with RNAP and demonstrate the importance of these contacts for transcription initiation. To get further insight into the mechanism of RNA priming, we determined the structure of initially transcribing complex of RNAP holoenzyme with 6-mer RNA, obtained by in crystallo transcription approach. The structure highlights RNAP-RNA contacts that stabilize the short RNA transcript in the active site and demonstrates that the RNA 5'-end displaces σ region 3.2 from its position near the active site, which likely plays a key role in σ ejection during the initiation-to-elongation transition. Given the structural conservation of the RNAP active site, the mechanism of de novo RNA priming appears to be conserved in all cellular RNAPs.
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Affiliation(s)
- Ritwika S Basu
- From the Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Brittany A Warner
- From the Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Vadim Molodtsov
- From the Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Danil Pupov
- the Laboratory of Molecular Genetics of Microorganisms, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Daria Esyunina
- the Laboratory of Molecular Genetics of Microorganisms, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Carlos Fernández-Tornero
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain, and
| | - Andrey Kulbachinskiy
- the Laboratory of Molecular Genetics of Microorganisms, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
| | - Katsuhiko S Murakami
- From the Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802,
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Gouge J, Rosario S, Romain F, Beguin P, Delarue M. Structures of intermediates along the catalytic cycle of terminal deoxynucleotidyltransferase: dynamical aspects of the two-metal ion mechanism. J Mol Biol 2013; 425:4334-52. [PMID: 23856622 DOI: 10.1016/j.jmb.2013.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/28/2013] [Accepted: 07/03/2013] [Indexed: 11/19/2022]
Abstract
Terminal deoxynucleotidyltransferase (Tdt) is a non-templated eukaryotic DNA polymerase of the polX family that is responsible for the random addition of nucleotides at the V(D)J junctions of immunoglobulins and T-cell receptors. Here we describe a series of high-resolution X-ray structures that mimic the pre-catalytic state, the post-catalytic state and a competent state that can be transformed into the two other ones in crystallo via the addition of dAMPcPP and Zn(2+), respectively. We examined the effect of Mn(2+), Co(2+) and Zn(2+) because they all have a marked influence on the kinetics of the reaction. We demonstrate a dynamic role of divalent transition metal ions bound to site A: (i) Zn(2+) (or Co(2+)) in Metal A site changes coordination from octahedral to tetrahedral after the chemical step, which explains the known higher affinity of Tdt for the primer strand when these ions are present, and (ii) metal A has to leave to allow the translocation of the primer strand and to clear the active site, a typical feature for a ratchet-like mechanism. Except for Zn(2+), the sugar puckering of the primer strand 3' terminus changes from C2'-endo to C3'-endo during catalysis. In addition, our data are compatible with a scheme where metal A is the last component that binds to the active site to complete its productive assembly, as already inferred in human pol beta. The new structures have potential implications for modeling pol mu, a closely related polX implicated in the repair of DNA double-strand breaks, in a complex with a DNA synapsis.
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Affiliation(s)
- Jérôme Gouge
- Unité de Dynamique Structurale des Macromolécules, Institut Pasteur, UMR 3528 du CNRS, 25 rue du Dr Roux, 75015 Paris, France
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Basu RS, Murakami KS. Watching the bacteriophage N4 RNA polymerase transcription by time-dependent soak-trigger-freeze X-ray crystallography. J Biol Chem 2012; 288:3305-11. [PMID: 23235152 DOI: 10.1074/jbc.m112.387712] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The challenge for structural biology is to understand atomic-level macromolecular motions during enzymatic reaction. X-ray crystallography can reveal high resolution structures; however, one perceived limitation is that it reveals only static views. Here we use time-dependent soak-trigger-freeze X-ray crystallography, namely, soaking nucleotide and divalent metal into the bacteriophage RNA polymerase (RNAP)-promoter DNA complex crystals to trigger the nucleotidyl transfer reaction and freezing crystals at different time points, to capture real-time intermediates in the pathway of transcription. In each crystal structure, different intensities and shapes of electron density maps corresponding to the nucleotide and metal were revealed at the RNAP active site which allow watching the nucleotide and metal bindings and the phosphodiester bond formation in a time perspective. Our study provides the temporal order of substrate assembly and metal co-factor binding at the active site of enzyme which completes our understanding of the two-metal-ion mechanism and fidelity mechanism in single-subunit RNAPs. The nucleotide-binding metal (Me(B)) is coordinated at the active site prior to the catalytic metal (Me(A)). Me(A) coordination is only temporal, established just before and dissociated immediately after phosphodiester bond formation. We captured these elusive intermediates exploiting the slow enzymatic reaction in crystallo. These results demonstrate that the simple time-dependent soak-trigger-freeze X-ray crystallography offers a direct means for monitoring enzymatic reactions.
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Affiliation(s)
- Ritwika S Basu
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Kaplan CD. Basic mechanisms of RNA polymerase II activity and alteration of gene expression in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:39-54. [PMID: 23022618 DOI: 10.1016/j.bbagrm.2012.09.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/18/2012] [Accepted: 09/20/2012] [Indexed: 01/12/2023]
Abstract
Transcription by RNA polymerase II (Pol II), and all RNA polymerases for that matter, may be understood as comprising two cycles. The first cycle relates to the basic mechanism of the transcription process wherein Pol II must select the appropriate nucleoside triphosphate (NTP) substrate complementary to the DNA template, catalyze phosphodiester bond formation, and translocate to the next position on the DNA template. Performing this cycle in an iterative fashion allows the synthesis of RNA chains that can be over one million nucleotides in length in some larger eukaryotes. Overlaid upon this enzymatic cycle, transcription may be divided into another cycle of three phases: initiation, elongation, and termination. Each of these phases has a large number of associated transcription factors that function to promote or regulate the gene expression process. Complicating matters, each phase of the latter transcription cycle are coincident with cotranscriptional RNA processing events. Additionally, transcription takes place within a highly dynamic and regulated chromatin environment. This chromatin environment is radically impacted by active transcription and associated chromatin modifications and remodeling, while also functioning as a major platform for Pol II regulation. This review will focus on our basic knowledge of the Pol II transcription mechanism, and how altered Pol II activity impacts gene expression in vivo in the model eukaryote Saccharomyces cerevisiae. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.
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Affiliation(s)
- Craig D Kaplan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128, USA.
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Sgrignani J, Magistrato A. The structural role of Mg2+ ions in a class I RNA polymerase ribozyme: a molecular simulation study. J Phys Chem B 2012; 116:2259-68. [PMID: 22268599 DOI: 10.1021/jp206475d] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
According to the RNA world hypothesis, self-replicating ribozymes, storing the genetic information and being able to perform catalysis, were the constituents of the first living organisms. In particular, RNA polymerase ribozymes, similar to current proteinaceous enzymatic polymerases, may have been able to promote the synthesis of RNA strands in a primitive world. Polymerase catalysis is usually assisted by Mg(2+) ions, but it is not always trivial to find out experimentally the number of Mg(2+) ions placed in the active site as well as the identity and the number of their coordination ligands. Here, we addressed this issue in an artificial class I ligase ribozyme. On the basis of a recently solved crystal structure, we constructed computational models of reactant and product states of this ribozyme, considering monometallic and bimetallic species. Our models were relaxed by force field based molecular dynamics (MD) simulations and mixed quantum-classical (QM/MM) MD. The structural and dynamical properties of these models were consistent with experimental data and were validated by a comparison with the catalytic sites of proteinaceous DNA and RNA polymerases. Consistently with enzymatic polymerases, our results suggest that class I RNA ligases most probably contain two magnesium ions in the active site and they may, therefore, catalyze the junction of two RNA strands via "a two Mg(2+) ions" mechanism.
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Affiliation(s)
- Jacopo Sgrignani
- CNR-IOM-Democritos National Simulation Center C/o International Studies for Advanced Studies (SISSA/ISAS), Via Bonomea 265, 34165, Trieste, Italy
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29
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Cheung ACM, Sainsbury S, Cramer P. Structural basis of initial RNA polymerase II transcription. EMBO J 2011; 30:4755-63. [PMID: 22056778 PMCID: PMC3243610 DOI: 10.1038/emboj.2011.396] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 10/10/2011] [Indexed: 01/22/2023] Open
Abstract
Several RNA polymerase II–nucleic acid crystal structures reveal the transition of the initiating polymerase from the open complex (OC) state to the initially transcribing complex (ITC) containing several RNA nucleotides. During transcription initiation by RNA polymerase (Pol) II, a transient open promoter complex (OC) is converted to an initially transcribing complex (ITC) containing short RNAs, and to a stable elongation complex (EC). We report structures of a Pol II–DNA complex mimicking part of the OC, and of complexes representing minimal ITCs with 2, 4, 5, 6, and 7 nucleotide (nt) RNAs, with and without a non-hydrolyzable nucleoside triphosphate (NTP) in the insertion site +1. The partial OC structure reveals that Pol II positions the melted template strand opposite the active site. The ITC-mimicking structures show that two invariant lysine residues anchor the 3′-proximal phosphate of short RNAs. Short DNA–RNA hybrids adopt a tilted conformation that excludes the +1 template nt from the active site. NTP binding induces complete DNA translocation and the standard hybrid conformation. Conserved NTP contacts indicate a universal mechanism of NTP selection. The essential residue Q1078 in the closed trigger loop binds the NTP 2′-OH group, explaining how the trigger loop couples catalysis to NTP selection, suppressing dNTP binding and DNA synthesis.
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Affiliation(s)
- Alan C M Cheung
- Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munich, Germany
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Chen Y, Basu R, Gleghorn ML, Murakami KS, Carey PR. Time-resolved events on the reaction pathway of transcript initiation by a single-subunit RNA polymerase: Raman crystallographic evidence. J Am Chem Soc 2011; 133:12544-55. [PMID: 21744806 DOI: 10.1021/ja201557w] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nucleotidyl transfer reaction leading to formation of the first phosphodiester bond has been followed in real time by Raman microscopy, as it proceeds in single crystals of the N4 phage virion RNA polymerase (RNAP). The reaction is initiated by soaking nucleoside triphosphate (NTP) substrates and divalent cations into the RNAP and promoter DNA complex crystal, where the phosphodiester bond formation is completed in about 40 min. This slow reaction allowed us to monitor the changes of the RNAP and DNA conformations as well as bindings of substrate and metal through Raman spectra taken every 5 min. Recently published snapshot X-ray crystal structures along the same reaction pathway assisted the spectroscopic assignments of changes in the enzyme and DNA, while isotopically labeled NTP substrates allowed differentiation of the Raman spectra of bases in substrates and DNA. We observed that substrates are bound at 2-7 min after soaking is commenced, the O-helix completes its conformational change, and binding of both divalent metals required for catalysis in the active site changes the conformation of the ribose triphosphate at position +1. These are followed by a slower decrease of NTP triphosphate groups due to phosphodiester bond formation that reaches completion at about 15 min and even slower complete release of the divalent metals at about 40 min. We have also shown that the O-helix movement can be driven by substrate binding only. The kinetics of the in crystallo nucleotidyl transfer reaction revealed in this study suggest that soaking the substrate and metal into the RNAP-DNA complex crystal for a few minutes generates novel and uncharacterized intermediates for future X-ray and spectroscopic analysis.
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Affiliation(s)
- Yuanyuan Chen
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, United States
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