1
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Ren Q, Guo X, Yang D, Zhao C, Zhang X, Xia X. A wide survey of heavy metals-induced in-vitro DNA replication stress characterized by rate-limited replication. Curr Res Toxicol 2024; 6:100152. [PMID: 38327637 PMCID: PMC10848000 DOI: 10.1016/j.crtox.2024.100152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/12/2024] [Accepted: 01/25/2024] [Indexed: 02/09/2024] Open
Abstract
Heavy metals (HMs) are environmental pollutants that pose a threat to human health and have been accepted to cause various diseases, including cancer and developmental disorders. DNA replication stress has been identified to be associated with such diseases. However, the effect of HMs exclusively on DNA replication stress is still not well understood. In this study, DNA replication stress induced by thirteen HMs was assessed using a simplified in-vitro DNA replication model. Two parameters, Cte/Ctc reflecting the cycle threshold value alteration and Ke/Kc reflecting the linear phase slope change, were calculated based on the DNA replication amplification curve to evaluate the rate of exponential and linear phases. These parameters were used to detect the replication rate reflecting in-vitro DNA replication stress induced by tested HMs. According to the effective concentrations and rate-limiting degree, HMs were ranked as follows: Hg, Ce > Pb > Zn > Cr > Cd > Co > Fe > Mn, Cu, Bi, Sr, Ni. Additionally, EDTA could relieve the DNA replication stress induced by some HMs. In conclusion, this study highlights the potential danger of HMs themselves on DNA replication and provides new insight into the possible links between HMs and DNA replication-related diseases.
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Affiliation(s)
- Qidong Ren
- Key Laboratory of Novel Food Resources Processing, Ministry of Agriculture and Rural Affairs/Key Laboratory of Agro-Products Processing Technology of Shandong Province/Institute of Agro-Food Science and Technology, Shandong Academy of Agricultural Sciences, 23788 Gongye North Road, Jinan 250100, China
- State Key Laboratory of Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xuejun Guo
- State Key Laboratory of Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Dong Yang
- Gene Engineering and Biotechnology Beijing Key Laboratory, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Chuanfang Zhao
- State Key Laboratory of Environmental Chemistry and Eco-Toxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xiangyuan Zhang
- State Key Laboratory of Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xinghui Xia
- State Key Laboratory of Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
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2
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Bocanegra R, Ortíz-Rodríguez M, Zumeta L, Plaza-G A I, Faro E, Ibarra B. DNA replication machineries: Structural insights from crystallography and electron microscopy. Enzymes 2023; 54:249-271. [PMID: 37945174 DOI: 10.1016/bs.enz.2023.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Since the discovery of DNA as the genetic material, scientists have been investigating how the information contained in this biological polymer is transmitted from generation to generation. X-ray crystallography, and more recently, cryo-electron microscopy techniques have been instrumental in providing essential information about the structure, functions and interactions of the DNA and the protein machinery (replisome) responsible for its replication. In this chapter, we highlight several works that describe the structure and structure-function relationships of the core components of the prokaryotic and eukaryotic replisomes. We also discuss the most recent studies on the structural organization of full replisomes.
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Affiliation(s)
| | | | - Lyra Zumeta
- IMDEA Nanociencia, Campus Cantoblanco, Madrid, Spain
| | | | - Elías Faro
- IMDEA Nanociencia, Campus Cantoblanco, Madrid, Spain
| | - Borja Ibarra
- IMDEA Nanociencia, Campus Cantoblanco, Madrid, Spain.
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3
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Sengupta A, Das K, Jha N, Akhter Y, Kumar A. Molecular evolution steered structural adaptations in the DNA polymerase III α subunit of halophilic bacterium Salinibacter ruber. Extremophiles 2023; 27:20. [PMID: 37481762 DOI: 10.1007/s00792-023-01306-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 07/14/2023] [Indexed: 07/25/2023]
Abstract
A significant portion of the earth has a salty environment, and the literature on bacterial survival mechanisms in salty environments is limited. During molecular evolution, halophiles increase acidic amino acid residues on their protein surfaces which leads to a negatively charged surface potential that helps them to maintain the protein integrity and protect them from denaturation by competing with salt ions. Through protein family analysis, we have investigated the molecular-level adaptive features of DNA polymerase III's catalytic subunit (alpha) and its structure-function relationship. This study throws light on the novel understanding of halophilic bacterial replication and the molecular basis of salt adaptation. Comparisons of the amino acid contents and electronegativity of halophilic and mesophilic bacterial proteins revealed adaptations that allow halophilic bacteria to thrive in high salt concentrations. A significantly lower isoelectric point of halophilic bacterial proteins indicates the acidic nature. Also, an abundance of disordered regions in halophiles suggests the requirement of the salt ions that play a crucial role in their stable protein folding. Despite having similar topology, mesophilic and halophilic proteins, a set of very prominent molecular modifications was observed in the alpha subunit of halophiles.
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Affiliation(s)
- Aveepsa Sengupta
- Department of Microbiology, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, India
| | - Kunwali Das
- Department of Microbiology, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, India
| | - Nidhi Jha
- Department of Microbiology, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, India
| | - Yusuf Akhter
- Department of Biotechnology, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow, Uttar Pradesh, 226025, India.
| | - Ashutosh Kumar
- Department of Microbiology, Tripura University (A Central University), Suryamaninagar, Agartala, Tripura, India.
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4
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Nelson-Rigg R, Fagan SP, Jaremko WJ, Pata JD. Pre-Steady-State Kinetic Characterization of an Antibiotic-Resistant Mutant of Staphylococcus aureus DNA Polymerase PolC. Antimicrob Agents Chemother 2023; 67:e0157122. [PMID: 37222615 PMCID: PMC10269047 DOI: 10.1128/aac.01571-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 04/17/2023] [Indexed: 05/25/2023] Open
Abstract
The emergence and spread of antibiotic resistance in bacterial pathogens are serious and ongoing threats to public health. Since chromosome replication is essential to cell growth and pathogenesis, the essential DNA polymerases in bacteria have long been targets of antimicrobial development, although none have yet advanced to the market. Here, we use transient-state kinetic methods to characterize the inhibition of the PolC replicative DNA polymerase from Staphylococcus aureus by 2-methoxyethyl-6-(3'-ethyl-4'-methylanilino)uracil (ME-EMAU), a member of the 6-anilinouracil compounds that specifically target PolC enzymes, which are found in low-GC content Gram-positive bacteria. We find that ME-EMAU binds to S. aureus PolC with a dissociation constant of 14 nM, more than 200-fold tighter than the previously reported inhibition constant, which was determined using steady-state kinetic methods. This tight binding is driven by a very slow off rate of 0.006 s-1. We also characterized the kinetics of nucleotide incorporation by PolC containing a mutation of phenylalanine 1261 to leucine (F1261L). The F1261L mutation decreases ME-EMAU binding affinity by at least 3,500-fold but also decreases the maximal rate of nucleotide incorporation by 11.5-fold. This suggests that bacteria acquiring this mutation would be likely to replicate slowly and be unable to out-compete wild-type strains in the absence of inhibitors, reducing the likelihood of the resistant bacteria propagating and spreading resistance.
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Affiliation(s)
- Rachel Nelson-Rigg
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - Sean P. Fagan
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
| | - William J. Jaremko
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Janice D. Pata
- Wadsworth Center, New York State Department of Health, Albany, New York, USA
- Department of Biomedical Sciences, University at Albany, Albany, New York, USA
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5
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Structural and Molecular Kinetic Features of Activities of DNA Polymerases. Int J Mol Sci 2022; 23:ijms23126373. [PMID: 35742812 PMCID: PMC9224347 DOI: 10.3390/ijms23126373] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/01/2022] [Accepted: 06/06/2022] [Indexed: 02/01/2023] Open
Abstract
DNA polymerases catalyze DNA synthesis during the replication, repair, and recombination of DNA. Based on phylogenetic analysis and primary protein sequences, DNA polymerases have been categorized into seven families: A, B, C, D, X, Y, and RT. This review presents generalized data on the catalytic mechanism of action of DNA polymerases. The structural features of different DNA polymerase families are described in detail. The discussion highlights the kinetics and conformational dynamics of DNA polymerases from all known polymerase families during DNA synthesis.
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6
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Fagan SP, Mukherjee P, Jaremko WJ, Nelson-Rigg R, Wilson RC, Dangerfield TL, Johnson KA, Lahiri I, Pata JD. Pyrophosphate release acts as a kinetic checkpoint during high-fidelity DNA replication by the Staphylococcus aureus replicative polymerase PolC. Nucleic Acids Res 2021; 49:8324-8338. [PMID: 34302475 PMCID: PMC8373059 DOI: 10.1093/nar/gkab613] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/29/2021] [Accepted: 07/21/2021] [Indexed: 12/22/2022] Open
Abstract
Bacterial replication is a fast and accurate process, with the bulk of genome duplication being catalyzed by the α subunit of DNA polymerase III within the bacterial replisome. Structural and biochemical studies have elucidated the overall properties of these polymerases, including how they interact with other components of the replisome, but have only begun to define the enzymatic mechanism of nucleotide incorporation. Using transient-state methods, we have determined the kinetic mechanism of accurate replication by PolC, the replicative polymerase from the Gram-positive pathogen Staphylococcus aureus. Remarkably, PolC can recognize the presence of the next correct nucleotide prior to completing the addition of the current nucleotide. By modulating the rate of pyrophosphate byproduct release, PolC can tune the speed of DNA synthesis in response to the concentration of the next incoming nucleotide. The kinetic mechanism described here would allow PolC to perform high fidelity replication in response to diverse cellular environments.
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Affiliation(s)
- Sean P Fagan
- Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Sciences, University at Albany, Albany, NY, USA
| | - Purba Mukherjee
- Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Sciences, University at Albany, Albany, NY, USA
| | - William J Jaremko
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Rachel Nelson-Rigg
- Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Sciences, University at Albany, Albany, NY, USA
| | - Ryan C Wilson
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Tyler L Dangerfield
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Kenneth A Johnson
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Indrajit Lahiri
- Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Sciences, University at Albany, Albany, NY, USA.,Department of Biological Sciences, Indian Institute of Science Education and Research, Mohali, Punjab, India
| | - Janice D Pata
- Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Biomedical Sciences, University at Albany, Albany, NY, USA
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7
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Simon MA, Ongpipattanakul C, Nair SK, van der Donk WA. Biosynthesis of fosfomycin in pseudomonads reveals an unexpected enzymatic activity in the metallohydrolase superfamily. Proc Natl Acad Sci U S A 2021; 118:e2019863118. [PMID: 34074759 PMCID: PMC8201877 DOI: 10.1073/pnas.2019863118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The epoxide-containing phosphonate natural product fosfomycin is a broad-spectrum antibiotic used in the treatment of cystitis. Fosfomycin is produced by both the plant pathogen Pseudomonas syringae and soil-dwelling streptomycetes. While the streptomycete pathway has recently been fully elucidated, the pseudomonad pathway is still mostly elusive. Through a systematic evaluation of heterologous expression of putative biosynthetic enzymes, we identified the central enzyme responsible for completing the biosynthetic pathway in pseudomonads. The missing transformation involves the oxidative decarboxylation of the intermediate 2-phosphonomethylmalate to a new intermediate, 3-oxo-4-phosphonobutanoate, by PsfC. Crystallographic studies reveal that PsfC unexpectedly belongs to a new class of diiron metalloenzymes that are part of the polymerase and histidinol phosphatase superfamily.
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Affiliation(s)
- Max A Simon
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Chayanid Ongpipattanakul
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Satish K Nair
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Wilfred A van der Donk
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- HHMI, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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8
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Zatopek KM, Alpaslan E, Evans T, Sauguet L, Gardner A. Novel ribonucleotide discrimination in the RNA polymerase-like two-barrel catalytic core of Family D DNA polymerases. Nucleic Acids Res 2020; 48:12204-12218. [PMID: 33137176 PMCID: PMC7708050 DOI: 10.1093/nar/gkaa986] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/08/2020] [Accepted: 10/12/2020] [Indexed: 02/06/2023] Open
Abstract
Family D DNA polymerase (PolD) is the essential replicative DNA polymerase for duplication of most archaeal genomes. PolD contains a unique two-barrel catalytic core absent from all other DNA polymerase families but found in RNA polymerases (RNAPs). While PolD has an ancestral RNA polymerase catalytic core, its active site has evolved the ability to discriminate against ribonucleotides. Until now, the mechanism evolved by PolD to prevent ribonucleotide incorporation was unknown. In all other DNA polymerase families, an active site steric gate residue prevents ribonucleotide incorporation. In this work, we identify two consensus active site acidic (a) and basic (b) motifs shared across the entire two-barrel nucleotide polymerase superfamily, and a nucleotide selectivity (s) motif specific to PolD versus RNAPs. A novel steric gate histidine residue (H931 in Thermococcus sp. 9°N PolD) in the PolD s-motif both prevents ribonucleotide incorporation and promotes efficient dNTP incorporation. Further, a PolD H931A steric gate mutant abolishes ribonucleotide discrimination and readily incorporates a variety of 2' modified nucleotides. Taken together, we construct the first putative nucleotide bound PolD active site model and provide structural and functional evidence for the emergence of DNA replication through the evolution of an ancestral RNAP two-barrel catalytic core.
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Affiliation(s)
| | - Ece Alpaslan
- New England Biolabs, 240 County Road Ipswich, MA 01938, USA
| | - Thomas C Evans
- New England Biolabs, 240 County Road Ipswich, MA 01938, USA
| | - Ludovic Sauguet
- Institut Pasteur, Unité de Dynamique Structurale des Macromolécules, 75015 Paris, France
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9
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Novel Antibiotics Targeting Bacterial Replicative DNA Polymerases. Antibiotics (Basel) 2020; 9:antibiotics9110776. [PMID: 33158178 PMCID: PMC7694242 DOI: 10.3390/antibiotics9110776] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/31/2020] [Accepted: 11/02/2020] [Indexed: 12/15/2022] Open
Abstract
Multidrug resistance is a worldwide problem that is an increasing threat to global health. Therefore, the development of new antibiotics that inhibit novel targets is of great urgency. Some of the most successful antibiotics inhibit RNA transcription, RNA translation, and DNA replication. Transcription and translation are inhibited by directly targeting the RNA polymerase or ribosome, respectively. DNA replication, in contrast, is inhibited indirectly through targeting of DNA gyrases, and there are currently no antibiotics that inhibit DNA replication by directly targeting the replisome. This contrasts with antiviral therapies where the viral replicases are extensively targeted. In the last two decades there has been a steady increase in the number of compounds that target the bacterial replisome. In particular a variety of inhibitors of the bacterial replicative polymerases PolC and DnaE have been described, with one of the DNA polymerase inhibitors entering clinical trials for the first time. In this review we will discuss past and current work on inhibition of DNA replication, and the potential of bacterial DNA polymerase inhibitors in particular as attractive targets for a new generation of antibiotics.
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10
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Koonin EV, Krupovic M, Ishino S, Ishino Y. The replication machinery of LUCA: common origin of DNA replication and transcription. BMC Biol 2020; 18:61. [PMID: 32517760 PMCID: PMC7281927 DOI: 10.1186/s12915-020-00800-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Origin of DNA replication is an enigma because the replicative DNA polymerases (DNAPs) are not homologous among the three domains of life, Bacteria, Archaea, and Eukarya. The homology between the archaeal replicative DNAP (PolD) and the large subunits of the universal RNA polymerase (RNAP) responsible for transcription suggests a parsimonious evolutionary scenario. Under this model, RNAPs and replicative DNAPs evolved from a common ancestor that functioned as an RNA-dependent RNA polymerase in the RNA-protein world that predated the advent of DNA replication. The replicative DNAP of the Last Universal Cellular Ancestor (LUCA) would be the ancestor of the archaeal PolD.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Mart Krupovic
- Archaeal Virology Unit, Institut Pasteur, 75015, Paris, France
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, 819-0395, Japan
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11
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Miyazono KI, Ishino S, Makita N, Ito T, Ishino Y, Tanokura M. Crystal structure of the novel lesion-specific endonuclease PfuEndoQ from Pyrococcus furiosus. Nucleic Acids Res 2019; 46:4807-4818. [PMID: 29660024 PMCID: PMC5961232 DOI: 10.1093/nar/gky261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/28/2018] [Indexed: 02/03/2023] Open
Abstract
Because base deaminations, which are promoted by high temperature, ionizing radiation, aerobic respiration and nitrosative stress, produce mutations during replication, deaminated bases must be repaired quickly to maintain genome integrity. Recently, we identified a novel lesion-specific endonuclease, PfuEndoQ, from Pyrococcus furiosus, and PfuEndoQ may be involved in the DNA repair pathway in Thermococcales of Archaea. PfuEndoQ recognizes a deaminated base and cleaves the phosphodiester bond 5' of the lesion site. To elucidate the structural basis of the substrate recognition and DNA cleavage mechanisms of PfuEndoQ, we determined the structure of PfuEndoQ using X-ray crystallography. The PfuEndoQ structure and the accompanying biochemical data suggest that PfuEndoQ recognizes a deaminated base using a highly conserved pocket adjacent to a Zn2+-binding site and hydrolyses a phosphodiester bond using two Zn2+ ions. The PfuEndoQ-DNA complex is stabilized by a Zn-binding domain and a C-terminal helical domain, and the complex may recruit downstream proteins in the DNA repair pathway.
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Affiliation(s)
- Ken-Ichi Miyazono
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Sonoko Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Naruto Makita
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Tomoko Ito
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yoshizumi Ishino
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, and Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
| | - Masaru Tanokura
- Laboratory of Basic Science on Healthy Longevity, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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12
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Sauguet L. The Extended "Two-Barrel" Polymerases Superfamily: Structure, Function and Evolution. J Mol Biol 2019; 431:4167-4183. [PMID: 31103775 DOI: 10.1016/j.jmb.2019.05.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 05/07/2019] [Accepted: 05/08/2019] [Indexed: 01/14/2023]
Abstract
DNA and RNA polymerases (DNAP and RNAP) play central roles in genome replication, maintenance and repair, as well as in the expression of genes through their transcription. Multisubunit RNAPs carry out transcription and are represented, without exception, in all cellular life forms as well as in nucleo-cytoplasmic DNA viruses. Since their discovery, multisubunit RNAPs have been the focus of intense structural and functional studies revealing that they all share a well-conserved active-site region called the two-barrel catalytic core. The two-barrel core hosts the polymerase active site, which is located at the interface between two double-psi β-barrel domains that contribute distinct amino acid residues to the active site in an asymmetrical fashion. Recently, sequencing and structural studies have added a surprising variety of DNA and RNA to the two-barrel superfamily, including the archaeal replicative DNAP (PolD), which extends the family to DNA-dependent DNAPs involved in replication. While all these polymerases share a minimal core that must have been present in their common ancestor, the two-barrel polymerase superfamily now encompasses a remarkable diversity of enzymes, including DNA-dependent RNAPs, RNA-dependent RNAPs, and DNA-dependent DNAPs, which participate in critical biological processes such as DNA transcription, DNA replication, and gene silencing. The present review will discuss both common features and differences among the extended two-barrel polymerase superfamily, focusing on the newly discovered members. Comparing their structures provides insights into the molecular mechanisms evolved by the contemporary two-barrel polymerases to accomplish their different biological functions.
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Affiliation(s)
- Ludovic Sauguet
- Institut Pasteur, Unité de Dynamique Structurale des Macromolécules, 75015 Paris, France.
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13
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Oakley AJ. A structural view of bacterial DNA replication. Protein Sci 2019; 28:990-1004. [PMID: 30945375 DOI: 10.1002/pro.3615] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 04/03/2019] [Indexed: 11/11/2022]
Abstract
DNA replication mechanisms are conserved across all organisms. The proteins required to initiate, coordinate, and complete the replication process are best characterized in model organisms such as Escherichia coli. These include nucleotide triphosphate-driven nanomachines such as the DNA-unwinding helicase DnaB and the clamp loader complex that loads DNA-clamps onto primer-template junctions. DNA-clamps are required for the processivity of the DNA polymerase III core, a heterotrimer of α, ε, and θ, required for leading- and lagging-strand synthesis. DnaB binds the DnaG primase that synthesizes RNA primers on both strands. Representative structures are available for most classes of DNA replication proteins, although there are gaps in our understanding of their interactions and the structural transitions that occur in nanomachines such as the helicase, clamp loader, and replicase core as they function. Reviewed here is the structural biology of these bacterial DNA replication proteins and prospects for future research.
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Affiliation(s)
- Aaron J Oakley
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia
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14
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Smith MR, Shock DD, Beard WA, Greenberg MM, Freudenthal BD, Wilson SH. A guardian residue hinders insertion of a Fapy•dGTP analog by modulating the open-closed DNA polymerase transition. Nucleic Acids Res 2019; 47:3197-3207. [PMID: 30649431 PMCID: PMC6451102 DOI: 10.1093/nar/gkz002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 12/17/2018] [Accepted: 01/03/2019] [Indexed: 01/07/2023] Open
Abstract
4,6-Diamino-5-formamidopyrimidine (Fapy•dG) is an abundant form of oxidative DNA damage that is mutagenic and contributes to the pathogenesis of human disease. When Fapy•dG is in its nucleotide triphosphate form, Fapy•dGTP, it is inefficiently cleansed from the nucleotide pool by the responsible enzyme in Escherichia coli MutT and its mammalian homolog MTH1. Therefore, under oxidative stress conditions, Fapy•dGTP could become a pro-mutagenic substrate for insertion into the genome by DNA polymerases. Here, we evaluated insertion kinetics and high-resolution ternary complex crystal structures of a configurationally stable Fapy•dGTP analog, β-C-Fapy•dGTP, with DNA polymerase β. The crystallographic snapshots and kinetic data indicate that binding of β-C-Fapy•dGTP impedes enzyme closure, thus hindering insertion. The structures reveal that an active site residue, Asp276, positions β-C-Fapy•dGTP so that it distorts the geometry of critical catalytic atoms. Removal of this guardian side chain permits enzyme closure and increases the efficiency of β-C-Fapy•dG insertion opposite dC. These results highlight the stringent requirements necessary to achieve a closed DNA polymerase active site poised for efficient nucleotide incorporation and illustrate how DNA polymerase β has evolved to hinder Fapy•dGTP insertion.
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Affiliation(s)
- Mallory R Smith
- Department of Biochemistry and Molecular Biology, and Department of Cancer Biology, University of Kansas Medical Center, 3901 Rainbow Blvd Mail Stop #3030, Kansas City, KS 66160, USA
| | - David D Shock
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA
| | - William A Beard
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, and Department of Cancer Biology, University of Kansas Medical Center, 3901 Rainbow Blvd Mail Stop #3030, Kansas City, KS 66160, USA,Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA,To whom correspondence should be addressed. Tel: +1 913 588 5560;
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA,Correspondence may also be addressed to Samuel H. Wilson. Tel: +1 984 287 3451;
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15
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Nasir N, Kisker C. Mechanistic insights into the enzymatic activity and inhibition of the replicative polymerase exonuclease domain from Mycobacterium tuberculosis. DNA Repair (Amst) 2019; 74:17-25. [PMID: 30641156 DOI: 10.1016/j.dnarep.2018.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/25/2018] [Accepted: 12/25/2018] [Indexed: 01/12/2023]
Abstract
DNA replication fidelity maintains low mutation rates in bacteria. The ε-subunit of a replisome generally acts as the main proofreader during replication, using its 3'-5' exonuclease activity to excise misincorporated bases thereby maintaining faithful replication. In Mycobacterium tuberculosis (Mtb), however, the polymerase and histidinol phosphatase (PHP) domain of the DNA polymerase DnaE1 is the primary proofreader. This domain thus maintains low mutation rates during replication and is an attractive target for drug development. Even though the structures of DnaE polymerases are available from various organisms, including Mtb, the mechanism of exonuclease activity remains elusive. In this study, we sought to unravel the mechanism and also to identify scaffolds that can specifically inhibit the exonuclease activity. To gain insight into the mode of action, we also characterized the PHP domain of the Mtb error-prone polymerase DnaE2 which shares a nearly identical active site with DnaE1-PHP. Kinetic and mutational studies allowed us to identify the critical residue involved in catalysis. Combined inhibition and computational studies also revealed a specific mode of inhibition of DnaE1-PHP by nucleoside diphosphates. Thus, this study lays the foundation for the rational design of novel inhibitors which target the Mtb replicative proofreader.
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Affiliation(s)
- Nazia Nasir
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany.
| | - Caroline Kisker
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, 97080 Würzburg, Germany
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16
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An updated structural classification of replicative DNA polymerases. Biochem Soc Trans 2019; 47:239-249. [PMID: 30647142 DOI: 10.1042/bst20180579] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/30/2018] [Accepted: 12/07/2018] [Indexed: 12/13/2022]
Abstract
Replicative DNA polymerases are nano-machines essential to life, which have evolved the ability to copy the genome with high fidelity and high processivity. In contrast with cellular transcriptases and ribosome machines, which evolved by accretion of complexity from a conserved catalytic core, no replicative DNA polymerase is universally conserved. Strikingly, four different families of DNA polymerases have evolved to perform DNA replication in the three domains of life. In Bacteria, the genome is replicated by DNA polymerases belonging to the A- and C-families. In Eukarya, genomic DNA is copied mainly by three distinct replicative DNA polymerases, Polα, Polδ, and Polε, which all belong to the B-family. Matters are more complicated in Archaea, which contain an unusual D-family DNA polymerase (PolD) in addition to PolB, a B-family replicative DNA polymerase that is homologous to the eukaryotic ones. PolD is a heterodimeric DNA polymerase present in all Archaea discovered so far, except Crenarchaea. While PolD is an essential replicative DNA polymerase, it is often underrepresented in the literature when the diversity of DNA polymerases is discussed. Recent structural studies have shown that the structures of both polymerase and proofreading active sites of PolD differ from other structurally characterized DNA polymerases, thereby extending the repertoire of folds known to perform DNA replication. This review aims to provide an updated structural classification of all replicative DNAPs and discuss their evolutionary relationships, both regarding the DNA polymerase and proofreading active sites.
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17
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Hernández-Morales R, Becerra A, Lazcano A. Alarmones as Vestiges of a Bygone RNA World. J Mol Evol 2019; 87:37-51. [PMID: 30604017 DOI: 10.1007/s00239-018-9883-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/15/2018] [Indexed: 12/11/2022]
Abstract
All known alarmones are ribonucleotides or ribonucleotide derivatives that are synthesized when cells are under stress conditions, triggering a stringent response that affects major processes such as replication, gene expression, and metabolism. The ample phylogenetic distribution of alarmones (e.g., cAMP, Ap(n)A, cGMP, AICAR, and ZTP) suggests that they are very ancient molecules that may have already been present in cellular systems prior to the evolutionary divergence of the Archaea, Bacteria, and Eukarya domains. Their chemical structure, wide biological distribution, and functional role in highly conserved cellular processes support the possibility that these modified nucleotides are molecular fossils of an epoch in the evolution of chemical signaling and metabolite sensing during which RNA molecules played a much more conspicuous role in biological catalysis and genetic information.
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Affiliation(s)
- Ricardo Hernández-Morales
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Cd. Universitaria, 04510, Mexico City, Mexico
| | - Arturo Becerra
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Cd. Universitaria, 04510, Mexico City, Mexico
| | - Antonio Lazcano
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Cd. Universitaria, 04510, Mexico City, Mexico. .,Miembro de El Colegio Nacional, Donceles 104, Centro Histórico, 06000, Mexico City, Mexico.
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18
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Xu ZQ, Dixon NE. Bacterial replisomes. Curr Opin Struct Biol 2018; 53:159-168. [PMID: 30292863 DOI: 10.1016/j.sbi.2018.09.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/07/2018] [Accepted: 09/17/2018] [Indexed: 01/18/2023]
Abstract
Bacterial replisomes are dynamic multiprotein DNA replication machines that are inherently difficult for structural studies. However, breakthroughs continue to come. The structures of Escherichia coli DNA polymerase III (core)-clamp-DNA subcomplexes solved by single-particle cryo-electron microscopy in both polymerization and proofreading modes and the discovery of the stochastic nature of the bacterial replisomes represent notable progress. The structures reveal an intricate interaction network in the polymerase-clamp subassembly, providing insights on how replisomes may work. Meantime, ensemble and single-molecule functional assays and fluorescence microscopy show that the bacterial replisomes can work in a decoupled and uncoordinated way, with polymerases quickly exchanging and both leading-strand and lagging-strand polymerases and the helicase working independently, contradictory to the elegant textbook view of a highly coordinated machine.
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Affiliation(s)
- Zhi-Qiang Xu
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Nicholas E Dixon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia.
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19
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Raper AT, Reed AJ, Suo Z. Kinetic Mechanism of DNA Polymerases: Contributions of Conformational Dynamics and a Third Divalent Metal Ion. Chem Rev 2018; 118:6000-6025. [DOI: 10.1021/acs.chemrev.7b00685] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Austin T. Raper
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Andrew J. Reed
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
| | - Zucai Suo
- Department of Chemistry and Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, United States
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20
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Kaguni JM. The Macromolecular Machines that Duplicate the Escherichia coli Chromosome as Targets for Drug Discovery. Antibiotics (Basel) 2018. [PMID: 29538288 PMCID: PMC5872134 DOI: 10.3390/antibiotics7010023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
DNA replication is an essential process. Although the fundamental strategies to duplicate chromosomes are similar in all free-living organisms, the enzymes of the three domains of life that perform similar functions in DNA replication differ in amino acid sequence and their three-dimensional structures. Moreover, the respective proteins generally utilize different enzymatic mechanisms. Hence, the replication proteins that are highly conserved among bacterial species are attractive targets to develop novel antibiotics as the compounds are unlikely to demonstrate off-target effects. For those proteins that differ among bacteria, compounds that are species-specific may be found. Escherichia coli has been developed as a model system to study DNA replication, serving as a benchmark for comparison. This review summarizes the functions of individual E. coli proteins, and the compounds that inhibit them.
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Affiliation(s)
- Jon M Kaguni
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA.
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21
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Parasuram R, Coulther TA, Hollander JM, Keston-Smith E, Ondrechen MJ, Beuning PJ. Prediction of Active Site and Distal Residues in E. coli DNA Polymerase III alpha Polymerase Activity. Biochemistry 2018; 57:1063-1072. [DOI: 10.1021/acs.biochem.7b01004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ramya Parasuram
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Timothy A. Coulther
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Judith M. Hollander
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Elise Keston-Smith
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Mary Jo Ondrechen
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Penny J. Beuning
- Department of Chemistry & Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
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22
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Ralec C, Henry E, Lemor M, Killelea T, Henneke G. Calcium-driven DNA synthesis by a high-fidelity DNA polymerase. Nucleic Acids Res 2017; 45:12425-12440. [PMID: 29040737 PMCID: PMC5716173 DOI: 10.1093/nar/gkx927] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 10/04/2017] [Indexed: 11/14/2022] Open
Abstract
Divalent metal ions, usually Mg2+, are required for both DNA synthesis and proofreading functions by DNA polymerases (DNA Pol). Although used as a non-reactive cofactor substitute for binding and crystallographic studies, Ca2+ supports DNA polymerization by only one DNA Pol, Dpo4. Here, we explore whether Ca2+-driven catalysis might apply to high-fidelity (HiFi) family B DNA Pols. The consequences of replacing Mg2+ by Ca2+ on base pairing at the polymerase active site as well as the editing of terminal nucleotides at the exonuclease active site of the archaeal Pyrococcus abyssi DNA Pol (PabPolB) are characterized and compared to other (families B, A, Y, X, D) DNA Pols. Based on primer extension assays, steady-state kinetics and ion-chased experiments, we demonstrate that Ca2+ (and other metal ions) activates DNA synthesis by PabPolB. While showing a slower rate of phosphodiester bond formation, nucleotide selectivity is improved over that of Mg2+. Further mechanistic studies show that the affinities for primer/template are higher in the presence of Ca2+ and reinforced by a correct incoming nucleotide. Conversely, no exonuclease degradation of the terminal nucleotides occurs with Ca2+. Evolutionary and mechanistic insights among DNA Pols are thus discussed.
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Affiliation(s)
- Céline Ralec
- Ifremer, Centre de Brest, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,CNRS, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,Université de Brest Occidentale, UBO, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Etienne Henry
- Ifremer, Centre de Brest, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,CNRS, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,Université de Brest Occidentale, UBO, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Mélanie Lemor
- Ifremer, Centre de Brest, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,CNRS, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,Université de Brest Occidentale, UBO, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Tom Killelea
- Ifremer, Centre de Brest, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,CNRS, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,Université de Brest Occidentale, UBO, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France
| | - Ghislaine Henneke
- Ifremer, Centre de Brest, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,CNRS, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France.,Université de Brest Occidentale, UBO, LM2E, UMR 6197, Technopole Brest-Iroise, 29280 Plouzané, France
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23
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Park J, Jergic S, Jeon Y, Cho WK, Lee R, Dixon NE, Lee JB. Dynamics of Proofreading by the E. coli Pol III Replicase. Cell Chem Biol 2017; 25:57-66.e4. [PMID: 29104063 DOI: 10.1016/j.chembiol.2017.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 08/09/2017] [Accepted: 09/27/2017] [Indexed: 02/05/2023]
Abstract
The αɛθ core of Escherichia coli DNA polymerase III (Pol III) associates with the β2 sliding clamp to processively synthesize DNA and remove misincorporated nucleotides. The α subunit is the polymerase while ɛ is the 3' to 5' proofreading exonuclease. In contrast to the polymerase activity of Pol III, dynamic features of proofreading are poorly understood. We used single-molecule assays to determine the excision rate and processivity of the β2-associated Pol III core, and observed that both properties are enhanced by mutational strengthening of the interaction between ɛ and β2. Thus, the ɛ-β2 contact is maintained in both the synthesis and proofreading modes. Remarkably, single-molecule real-time fluorescence imaging revealed the dynamics of transfer of primer-template DNA between the polymerase and proofreading sites, showing that it does not involve breaking of the physical interaction between ɛ and β2.
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Affiliation(s)
- Jonghyun Park
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea
| | - Slobodan Jergic
- Centre for Medical and Molecular Bioscience, University of Wollongong & Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Yongmoon Jeon
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea
| | - Won-Ki Cho
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea
| | - Ryanggeun Lee
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea
| | - Nicholas E Dixon
- Centre for Medical and Molecular Bioscience, University of Wollongong & Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
| | - Jong-Bong Lee
- Department of Physics, Pohang University of Science & Technology (POSTECH), Pohang 37673, Korea; School of Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang 37673, Korea.
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24
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High-fidelity DNA replication in Mycobacterium tuberculosis relies on a trinuclear zinc center. Nat Commun 2017; 8:855. [PMID: 29021523 PMCID: PMC5636811 DOI: 10.1038/s41467-017-00886-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/02/2017] [Indexed: 01/07/2023] Open
Abstract
High-fidelity DNA replication depends on a proofreading 3′–5′ exonuclease that is associated with the replicative DNA polymerase. The replicative DNA polymerase DnaE1 from the major pathogen Mycobacterium tuberculosis (Mtb) uses its intrinsic PHP-exonuclease that is distinct from the canonical DEDD exonucleases found in the Escherichia coli and eukaryotic replisomes. The mechanism of the PHP-exonuclease is not known. Here, we present the crystal structure of the Mtb DnaE1 polymerase. The PHP-exonuclease has a trinuclear zinc center, coordinated by nine conserved residues. Cryo-EM analysis reveals the entry path of the primer strand in the PHP-exonuclease active site. Furthermore, the PHP-exonuclease shows a striking similarity to E. coli endonuclease IV, which provides clues regarding the mechanism of action. Altogether, this work provides important insights into the PHP-exonuclease and reveals unique properties that make it an attractive target for novel anti-mycobacterial drugs. The polymerase and histidinol phosphatase (PHP) domain in the DNA polymerase DnaE1 is essential for mycobacterial high-fidelity DNA replication. Here, the authors determine the DnaE1 crystal structure, which reveals the PHP-exonuclease mechanism that can be exploited for antibiotic development.
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25
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Abstract
Faithful replication and maintenance of the genome are essential to the ability of any organism to survive and propagate. For an obligate pathogen such as Mycobacterium tuberculosis that has to complete successive cycles of transmission, infection, and disease in order to retain a foothold in the human population, this requires that genome replication and maintenance must be accomplished under the metabolic, immune, and antibiotic stresses encountered during passage through variable host environments. Comparative genomic analyses have established that chromosomal mutations enable M. tuberculosis to adapt to these stresses: the emergence of drug-resistant isolates provides direct evidence of this capacity, so too the well-documented genetic diversity among M. tuberculosis lineages across geographic loci, as well as the microvariation within individual patients that is increasingly observed as whole-genome sequencing methodologies are applied to clinical samples and tuberculosis (TB) disease models. However, the precise mutagenic mechanisms responsible for M. tuberculosis evolution and adaptation are poorly understood. Here, we summarize current knowledge of the machinery responsible for DNA replication in M. tuberculosis, and discuss the potential contribution of the expanded complement of mycobacterial DNA polymerases to mutagenesis. We also consider briefly the possible role of DNA replication-in particular, its regulation and coordination with cell division-in the ability of M. tuberculosis to withstand antibacterial stresses, including host immune effectors and antibiotics, through the generation at the population level of a tolerant state, or through the formation of a subpopulation of persister bacilli-both of which might be relevant to the emergence and fixation of genetic drug resistance.
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26
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Murison DA, Ollivierre JN, Huang Q, Budil DE, Beuning PJ. Altering the N-terminal arms of the polymerase manager protein UmuD modulates protein interactions. PLoS One 2017; 12:e0173388. [PMID: 28273172 PMCID: PMC5342242 DOI: 10.1371/journal.pone.0173388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 02/14/2017] [Indexed: 12/02/2022] Open
Abstract
Escherichia coli cells that are exposed to DNA damaging agents invoke the SOS response that involves expression of the umuD gene products, along with more than 50 other genes. Full-length UmuD is expressed as a 139-amino-acid protein, which eventually cleaves its N-terminal 24 amino acids to form UmuD'. The N-terminal arms of UmuD are dynamic and contain recognition sites for multiple partner proteins. Cleavage of UmuD to UmuD' dramatically affects the function of the protein and activates UmuC for translesion synthesis (TLS) by forming DNA Polymerase V. To probe the roles of the N-terminal arms in the cellular functions of the umuD gene products, we constructed additional N-terminal truncated versions of UmuD: UmuD 8 (UmuD Δ1-7) and UmuD 18 (UmuD Δ1-17). We found that the loss of just the N-terminal seven (7) amino acids of UmuD results in changes in conformation of the N-terminal arms, as determined by electron paramagnetic resonance spectroscopy with site-directed spin labeling. UmuD 8 is cleaved as efficiently as full-length UmuD in vitro and in vivo, but expression of a plasmid-borne non-cleavable variant of UmuD 8 causes hypersensitivity to UV irradiation, which we determined is the result of a copy-number effect. UmuD 18 does not cleave to form UmuD', but confers resistance to UV radiation. Moreover, removal of the N-terminal seven residues of UmuD maintained its interactions with the alpha polymerase subunit of DNA polymerase III as well as its ability to disrupt interactions between alpha and the beta processivity clamp, whereas deletion of the N-terminal 17 residues resulted in decreases in binding to alpha and in the ability to disrupt the alpha-beta interaction. We find that UmuD 8 mimics full-length UmuD in many respects, whereas UmuD 18 lacks a number of functions characteristic of UmuD.
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Affiliation(s)
- David A. Murison
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - Jaylene N. Ollivierre
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - Qiuying Huang
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - David E. Budil
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - Penny J. Beuning
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
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27
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Sauguet L, Raia P, Henneke G, Delarue M. Shared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography. Nat Commun 2016; 7:12227. [PMID: 27548043 PMCID: PMC4996933 DOI: 10.1038/ncomms12227] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/10/2016] [Indexed: 02/06/2023] Open
Abstract
Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all other known DNA polymerases (DNAPs). Rather, the PolD DP2 catalytic core has the same ‘double-psi β-barrel' architecture seen in the RNA polymerase (RNAP) superfamily, which includes multi-subunit transcriptases of all domains of life, homodimeric RNA-silencing pathway RNAPs and atypical viral RNAPs. This finding bridges together, in non-viral world, DNA transcription and DNA replication within the same protein superfamily. This study documents further the complex evolutionary history of the DNA replication apparatus in different domains of life and proposes a classification of all extant DNAPs. The structures of many DNA polymerases is known, but PolD was a missing piece. Here, the authors report the crystal structure of this protein and use it to connect the DNA replication machinery with the transcription machinery in the same protein family.
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Affiliation(s)
- Ludovic Sauguet
- Unit of Structural Dynamics of Macromolecules, Pasteur Institute and CNRS UMR 3528, 75015 Paris, France
| | - Pierre Raia
- Unit of Structural Dynamics of Macromolecules, Pasteur Institute and CNRS UMR 3528, 75015 Paris, France.,Pierre and Marie Curie University, Paris 6, 75006 Paris, France
| | - Ghislaine Henneke
- Ifremer, UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France.,UBO, UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France.,CNRS, UMR 6197, Laboratoire de Microbiologie des Environnements Extrêmes, 29280 Plouzané, France
| | - Marc Delarue
- Unit of Structural Dynamics of Macromolecules, Pasteur Institute and CNRS UMR 3528, 75015 Paris, France
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28
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Gao Y, Yang W. Capture of a third Mg²⁺ is essential for catalyzing DNA synthesis. Science 2016; 352:1334-7. [PMID: 27284197 DOI: 10.1126/science.aad9633] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 05/10/2016] [Indexed: 12/23/2022]
Abstract
It is generally assumed that an enzyme-substrate (ES) complex contains all components necessary for catalysis and that conversion to products occurs by rearrangement of atoms, protons, and electrons. However, we find that DNA synthesis does not occur in a fully assembled DNA polymerase-DNA-deoxynucleoside triphosphate complex with two canonical metal ions bound. Using time-resolved x-ray crystallography, we show that the phosphoryltransfer reaction takes place only after the ES complex captures a third divalent cation that is not coordinated by the enzyme. Binding of the third cation is incompatible with the basal ES complex and requires thermal activation of the ES for entry. It is likely that the third cation provides the ultimate boost over the energy barrier to catalysis of DNA synthesis.
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Affiliation(s)
- Yang Gao
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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29
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Abstract
DNA replication in Escherichia coli initiates at oriC, the origin of replication and proceeds bidirectionally, resulting in two replication forks that travel in opposite directions from the origin. Here, we focus on events at the replication fork. The replication machinery (or replisome), first assembled on both forks at oriC, contains the DnaB helicase for strand separation, and the DNA polymerase III holoenzyme (Pol III HE) for DNA synthesis. DnaB interacts transiently with the DnaG primase for RNA priming on both strands. The Pol III HE is made up of three subassemblies: (i) the αɛθ core polymerase complex that is present in two (or three) copies to simultaneously copy both DNA strands, (ii) the β2 sliding clamp that interacts with the core polymerase to ensure its processivity, and (iii) the seven-subunit clamp loader complex that loads β2 onto primer-template junctions and interacts with the α polymerase subunit of the core and the DnaB helicase to organize the two (or three) core polymerases. Here, we review the structures of the enzymatic components of replisomes, and the protein-protein and protein-DNA interactions that ensure they remain intact while undergoing substantial dynamic changes as they function to copy both the leading and lagging strands simultaneously during coordinated replication.
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Affiliation(s)
- J S Lewis
- Centre for Medical & Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - S Jergic
- Centre for Medical & Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - N E Dixon
- Centre for Medical & Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.
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30
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Gu S, Li W, Zhang H, Fleming J, Yang W, Wang S, Wei W, Zhou J, Zhu G, Deng J, Hou J, Zhou Y, Lin S, Zhang XE, Bi L. The β2 clamp in the Mycobacterium tuberculosis DNA polymerase III αβ2ε replicase promotes polymerization and reduces exonuclease activity. Sci Rep 2016; 6:18418. [PMID: 26822057 PMCID: PMC4731781 DOI: 10.1038/srep18418] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/17/2015] [Indexed: 12/20/2022] Open
Abstract
DNA polymerase III (DNA pol III) is a multi-subunit replication machine responsible for the accurate and rapid replication of bacterial genomes, however, how it functions in Mycobacterium tuberculosis (Mtb) requires further investigation. We have reconstituted the leading-strand replication process of the Mtb DNA pol III holoenzyme in vitro, and investigated the physical and functional relationships between its key components. We verify the presence of an αβ2ε polymerase-clamp-exonuclease replicase complex by biochemical methods and protein-protein interaction assays in vitro and in vivo and confirm that, in addition to the polymerase activity of its α subunit, Mtb DNA pol III has two potential proofreading subunits; the α and ε subunits. During DNA replication, the presence of the β2 clamp strongly promotes the polymerization of the αβ2ε replicase and reduces its exonuclease activity. Our work provides a foundation for further research on the mechanism by which the replication machinery switches between replication and proofreading and provides an experimental platform for the selection of antimicrobials targeting DNA replication in Mtb.
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Affiliation(s)
- Shoujin Gu
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjuan Li
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongtai Zhang
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Joy Fleming
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Weiqiang Yang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shihua Wang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wenjing Wei
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jie Zhou
- The Fourth People's Hospital, Foshan 528000, China
| | - Guofeng Zhu
- Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China
| | - Jiaoyu Deng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Jian Hou
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ying Zhou
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shiqiang Lin
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xian-En Zhang
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lijun Bi
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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31
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Abstract
The machines that decode and regulate genetic information require the translation, transcription and replication pathways essential to all living cells. Thus, it might be expected that all cells share the same basic machinery for these pathways that were inherited from the primordial ancestor cell from which they evolved. A clear example of this is found in the translation machinery that converts RNA sequence to protein. The translation process requires numerous structural and catalytic RNAs and proteins, the central factors of which are homologous in all three domains of life, bacteria, archaea and eukarya. Likewise, the central actor in transcription, RNA polymerase, shows homology among the catalytic subunits in bacteria, archaea and eukarya. In contrast, while some "gears" of the genome replication machinery are homologous in all domains of life, most components of the replication machine appear to be unrelated between bacteria and those of archaea and eukarya. This review will compare and contrast the central proteins of the "replisome" machines that duplicate DNA in bacteria, archaea and eukarya, with an eye to understanding the issues surrounding the evolution of the DNA replication apparatus.
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Affiliation(s)
- Nina Y Yao
- a DNA Replication Laboratory, The Rockefeller University , New York , NY , USA and
| | - Mike E O'Donnell
- a DNA Replication Laboratory, The Rockefeller University , New York , NY , USA and.,b Howard Hughes Medical Institute, The Rockefeller University , New York , NY , USA
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32
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Fernandez-Leiro R, Conrad J, Scheres SH, Lamers MH. cryo-EM structures of the E. coli replicative DNA polymerase reveal its dynamic interactions with the DNA sliding clamp, exonuclease and τ. eLife 2015; 4. [PMID: 26499492 PMCID: PMC4703070 DOI: 10.7554/elife.11134] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/23/2015] [Indexed: 11/13/2022] Open
Abstract
The replicative DNA polymerase PolIIIα from Escherichia coli is a uniquely fast and processive enzyme. For its activity it relies on the DNA sliding clamp β, the proofreading exonuclease ε and the C-terminal domain of the clamp loader subunit τ. Due to the dynamic nature of the four-protein complex it has long been refractory to structural characterization. Here we present the 8 Å resolution cryo-electron microscopy structures of DNA-bound and DNA-free states of the PolIII-clamp-exonuclease-τc complex. The structures show how the polymerase is tethered to the DNA through multiple contacts with the clamp and exonuclease. A novel contact between the polymerase and clamp is made in the DNA bound state, facilitated by a large movement of the polymerase tail domain and τc. These structures provide crucial insights into the organization of the catalytic core of the replisome and form an important step towards determining the structure of the complete holoenzyme.
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Affiliation(s)
| | - Julian Conrad
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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33
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Painter RE, Adam GC, Arocho M, DiNunzio E, Donald RGK, Dorso K, Genilloud O, Gill C, Goetz M, Hairston NN, Murgolo N, Nare B, Olsen DB, Powles M, Racine F, Su J, Vicente F, Wisniewski D, Xiao L, Hammond M, Young K. Elucidation of DnaE as the Antibacterial Target of the Natural Product, Nargenicin. ACTA ACUST UNITED AC 2015; 22:1362-73. [PMID: 26456734 DOI: 10.1016/j.chembiol.2015.08.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 08/10/2015] [Accepted: 08/25/2015] [Indexed: 01/14/2023]
Abstract
Resistance to existing classes of antibiotics drives the need for discovery of novel compounds with unique mechanisms of action. Nargenicin A1, a natural product with limited antibacterial spectrum, was rediscovered in a whole-cell antisense assay. Macromolecular labeling in both Staphylococcus aureus and an Escherichia coli tolC efflux mutant revealed selective inhibition of DNA replication not due to gyrase or topoisomerase IV inhibition. S. aureus nargenicin-resistant mutants were selected at a frequency of ∼1 × 10(-9), and whole-genome resequencing found a single base-pair change in the dnaE gene, a homolog of the E. coli holoenzyme α subunit. A DnaE single-enzyme assay was exquisitely sensitive to inhibition by nargenicin, and other in vitro characterization studies corroborated DnaE as the target. Medicinal chemistry efforts may expand the spectrum of this novel mechanism antibiotic.
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Affiliation(s)
- Ronald E Painter
- In vitro Pharmacology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Gregory C Adam
- Screening and Protein Sciences, Merck Research Laboratories, North Wales, PA 19454, USA
| | - Marta Arocho
- Medicinal Chemistry, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Edward DiNunzio
- In vitro Pharmacology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Robert G K Donald
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Karen Dorso
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Olga Genilloud
- Centro de Investigación Básica (CIBE), Merck Sharp & Dhome de España, S.A., 28027 Madrid, Spain
| | - Charles Gill
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Michael Goetz
- Medicinal Chemistry, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Nichelle N Hairston
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Nicholas Murgolo
- Discovery Pharmacogenomics, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Bakela Nare
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - David B Olsen
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Maryann Powles
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Fred Racine
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Jing Su
- Medicinal Chemistry, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Francisca Vicente
- Centro de Investigación Básica (CIBE), Merck Sharp & Dhome de España, S.A., 28027 Madrid, Spain
| | - Douglas Wisniewski
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Li Xiao
- Medicinal Chemistry, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Milton Hammond
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA
| | - Katherine Young
- Infectious Disease Biology, Merck Research Laboratories, Kenilworth, NJ 07033, USA.
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34
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Abstract
This review describes the components of the Escherichia coli replisome and the dynamic process in which they function and interact under normal conditions. It also briefly describes the behavior of the replisome during situations in which normal replication fork movement is disturbed, such as when the replication fork collides with sites of DNA damage. E. coli DNA Pol III was isolated first from a polA mutant E. coli strain that lacked the relatively abundant DNA Pol I activity. Further biochemical studies, and the use of double mutant strains, revealed Pol III to be the replicative DNA polymerase essential to cell viability. In a replisome, DnaG primase must interact with DnaB for activity, and this constraint ensures that new RNA primers localize to the replication fork. The leading strand polymerase continually synthesizes DNA in the direction of the replication fork, whereas the lagging-strand polymerase synthesizes short, discontinuous Okazaki fragments in the opposite direction. Discontinuous lagging-strand synthesis requires that the polymerase rapidly dissociate from each new completed Okazaki fragment in order to begin the extension of a new RNA primer. Lesion bypass can be thought of as a two-step reaction that starts with the incorporation of a nucleotide opposite the lesion, followed by the extension of the resulting distorted primer terminus. A remarkable property of E. coli, and many other eubacterial organisms, is the speed at which it propagates. Rapid cell division requires the presence of an extremely efficient replication machinery for the rapid and faithful duplication of the genome.
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35
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Lindow JC, Dohrmann PR, McHenry CS. DNA Polymerase α Subunit Residues and Interactions Required for Efficient Initiation Complex Formation Identified by a Genetic Selection. J Biol Chem 2015; 290:16851-60. [PMID: 25987558 DOI: 10.1074/jbc.m115.661090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Indexed: 11/06/2022] Open
Abstract
Biophysical and structural studies have defined many of the interactions that occur between individual components or subassemblies of the bacterial replicase, DNA polymerase III holoenzyme (Pol III HE). Here, we extended our knowledge of residues and interactions that are important for the first step of the replicase reaction: the ATP-dependent formation of an initiation complex between the Pol III HE and primed DNA. We exploited a genetic selection using a dominant negative variant of the polymerase catalytic subunit that can effectively compete with wild-type Pol III α and form initiation complexes, but cannot elongate. Suppression of the dominant negative phenotype was achieved by secondary mutations that were ineffective in initiation complex formation. The corresponding proteins were purified and characterized. One class of mutant mapped to the PHP domain of Pol III α, ablating interaction with the ϵ proofreading subunit and distorting the polymerase active site in the adjacent polymerase domain. Another class of mutation, found near the C terminus, interfered with τ binding. A third class mapped within the known β-binding domain, decreasing interaction with the β2 processivity factor. Surprisingly, mutations within the β binding domain also ablated interaction with τ, suggesting a larger τ binding site than previously recognized.
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Affiliation(s)
- Janet C Lindow
- From the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80303
| | - Paul R Dohrmann
- From the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80303
| | - Charles S McHenry
- From the Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80303
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36
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DNA replication fidelity in Mycobacterium tuberculosis is mediated by an ancestral prokaryotic proofreader. Nat Genet 2015; 47:677-81. [PMID: 25894501 PMCID: PMC4449270 DOI: 10.1038/ng.3269] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 03/11/2015] [Indexed: 01/27/2023]
Abstract
The DNA replication machinery is an important target for antibiotic development for increasingly drug resistant bacteria including Mycobacterium tuberculosis1. While blocking DNA replication leads to cell death, disrupting the processes used to ensure replication fidelity can accelerate mutation and the evolution of drug resistance. In E. coli, the proofreading subunit of the replisome, the ε-exonuclease, is essential for high fidelity DNA replication2; however, we find that it is completely dispensable in M. tuberculosis. Rather, the mycobacterial replicative polymerase, DnaE1, encodes a novel editing function that proofreads DNA replication, mediated by an intrinsic 3′-5′ exonuclease activity within its PHP domain. Inactivation of the DnaE1 PHP domain increases the mutation rate by greater than 3,000 fold. Moreover, phylogenetic analysis of DNA replication proofreading in the bacterial kingdom suggests that E. coli is a phylogenetic outlier and that PHP-domain mediated proofreading is widely conserved and indeed may be the ancestral prokaryotic proofreader.
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37
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Jadaun A, Sudhakar D R, Subbarao N, Dixit A. In silico screening for novel inhibitors of DNA polymerase III alpha subunit of Mycobacterium tuberculosis (MtbDnaE2, H37Rv). PLoS One 2015; 10:e0119760. [PMID: 25811866 PMCID: PMC4374717 DOI: 10.1371/journal.pone.0119760] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 01/15/2015] [Indexed: 01/19/2023] Open
Abstract
Tuberculosis, a pandemic disease is caused by Mycobacterium tuberculosis (Mtb). DNA polymerase III encoded by DnaE2 of Mtb is specifically required for its survival in vivo, and hence can be considered to be a potential drug target. Amino acid sequence analysis of the MtbDnaE2 and its human counterpart does not show any significant similarity. Therefore, a 3D model of the MtbDnaE2 was generated using Modeller 9v10 with the template structure of E. Coli DNA polymerase III alpha subunit (2HNH_A). The generated models were validated using a number of programmes such as RAMPAGE/PROCHECK, VERIFY_3D, and ProSA. MtbDnaE2 has few conserved residues and four conserved domains similar to that present in DNA polymerase III of E. coli. In silico screening was performed with bioactive anti-tuberculosis compounds and 6-AU (a known inhibitor of DNA polymerase III of Bacillus subtilis) and its analogues against the modeled MtbDnaE2 structure. Docking was performed using GOLD v5.2 software which resulted in the identification of top ten compounds with high GOLD fitness scores and binding affinity (X-Score). To further evaluate the efficacy of these compounds, in silico ADMET analysis was performed using MedChem Designer v3. Given their high binding affinity to the targeted MtbDnaE2, which is essential for DNA replication in the Mtb and good ADMET properties, these compounds are promising candidates for further evaluation and development as anti-tubercular agents.
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Affiliation(s)
- Alka Jadaun
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Raja Sudhakar D
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - N. Subbarao
- School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Aparna Dixit
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
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38
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The case for an early biological origin of DNA. J Mol Evol 2014; 79:204-12. [PMID: 25425102 PMCID: PMC4247479 DOI: 10.1007/s00239-014-9656-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 11/18/2014] [Indexed: 11/16/2022]
Abstract
All life generates deoxyribonucleotides, the building blocks of DNA, via ribonucleotide reductases (RNRs). The complexity of this reaction suggests it did not evolve until well after the advent of templated protein synthesis, which in turn suggests DNA evolved later than both RNA and templated protein synthesis. However, deoxyribonucleotides may have first been synthesised via an alternative, chemically simpler route—the reversal of the deoxyriboaldolase (DERA) step in deoxyribonucleotide salvage. In light of recent work demonstrating that this reaction can drive synthesis of deoxyribonucleosides, we consider what pressures early adoption of this pathway would have placed on cell metabolism. This in turn provides a rationale for the replacement of DERA-dependent DNA production by RNR-dependent production.
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39
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Bienstock RJ, Beard WA, Wilson SH. Phylogenetic analysis and evolutionary origins of DNA polymerase X-family members. DNA Repair (Amst) 2014; 22:77-88. [PMID: 25112931 DOI: 10.1016/j.dnarep.2014.07.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 06/25/2014] [Accepted: 07/09/2014] [Indexed: 01/19/2023]
Abstract
Mammalian DNA polymerase (pol) β is the founding member of a large group of DNA polymerases now termed the X-family. DNA polymerase β has been kinetically, structurally, and biologically well characterized and can serve as a phylogenetic reference. Accordingly, we have performed a phylogenetic analysis to understand the relationship between pol β and other members of the X-family of DNA polymerases. The bacterial X-family DNA polymerases, Saccharomyces cerevisiae pol IV, and four mammalian X-family polymerases appear to be directly related. These enzymes originated from an ancient common ancestor characterized in two Bacillus species. Understanding distinct functions for each of the X-family polymerases, evolving from a common bacterial ancestor is of significant interest in light of the specialized roles of these enzymes in DNA metabolism.
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Affiliation(s)
- Rachelle J Bienstock
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States
| | - William A Beard
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States
| | - Samuel H Wilson
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, United States.
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40
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Sojo V, Pomiankowski A, Lane N. A bioenergetic basis for membrane divergence in archaea and bacteria. PLoS Biol 2014; 12:e1001926. [PMID: 25116890 PMCID: PMC4130499 DOI: 10.1371/journal.pbio.1001926] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 07/02/2014] [Indexed: 01/03/2023] Open
Abstract
Membrane bioenergetics are universal, yet the phospholipid membranes of archaea and bacteria-the deepest branches in the tree of life-are fundamentally different. This deep divergence in membrane chemistry is reflected in other stark differences between the two domains, including ion pumping and DNA replication. We resolve this paradox by considering the energy requirements of the last universal common ancestor (LUCA). We develop a mathematical model based on the premise that LUCA depended on natural proton gradients. Our analysis shows that such gradients can power carbon and energy metabolism, but only in leaky cells with a proton permeability equivalent to fatty acid vesicles. Membranes with lower permeability (equivalent to modern phospholipids) collapse free-energy availability, precluding exploitation of natural gradients. Pumping protons across leaky membranes offers no advantage, even when permeability is decreased 1,000-fold. We hypothesize that a sodium-proton antiporter (SPAP) provided the first step towards modern membranes. SPAP increases the free energy available from natural proton gradients by ∼60%, enabling survival in 50-fold lower gradients, thereby facilitating ecological spread and divergence. Critically, SPAP also provides a steadily amplifying advantage to proton pumping as membrane permeability falls, for the first time favoring the evolution of ion-tight phospholipid membranes. The phospholipids of archaea and bacteria incorporate different stereoisomers of glycerol phosphate. We conclude that the enzymes involved took these alternatives by chance in independent populations that had already evolved distinct ion pumps. Our model offers a quantitatively robust explanation for why membrane bioenergetics are universal, yet ion pumps and phospholipid membranes arose later and independently in separate populations. Our findings elucidate the paradox that archaea and bacteria share DNA transcription, ribosomal translation, and ATP synthase, yet differ in equally fundamental traits that depend on the membrane, including DNA replication.
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Affiliation(s)
- Víctor Sojo
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- CoMPLEX, University College London, London, United Kingdom
| | - Andrew Pomiankowski
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- CoMPLEX, University College London, London, United Kingdom
| | - Nick Lane
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- CoMPLEX, University College London, London, United Kingdom
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41
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Yuan Q, McHenry CS. Cycling of the E. coli lagging strand polymerase is triggered exclusively by the availability of a new primer at the replication fork. Nucleic Acids Res 2013; 42:1747-56. [PMID: 24234450 PMCID: PMC3919610 DOI: 10.1093/nar/gkt1098] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Two models have been proposed for triggering release of the lagging strand polymerase at the replication fork, enabling cycling to the primer for the next Okazaki fragment—either collision with the 5′-end of the preceding fragment (collision model) or synthesis of a new primer by primase (signaling model). Specific perturbation of lagging strand elongation on minicircles with a highly asymmetric G:C distribution with ddGTP or dGDPNP yielded results that confirmed the signaling model and ruled out the collision model. We demonstrated that the presence of a primer, not primase per se, provides the signal that triggers cycling. Lagging strand synthesis proceeds much faster than leading strand synthesis, explaining why gaps between Okazaki fragments are not found under physiological conditions.
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Affiliation(s)
- Quan Yuan
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
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42
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Timinskas K, Balvočiūtė M, Timinskas A, Venclovas Č. Comprehensive analysis of DNA polymerase III α subunits and their homologs in bacterial genomes. Nucleic Acids Res 2013; 42:1393-413. [PMID: 24106089 PMCID: PMC3919608 DOI: 10.1093/nar/gkt900] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The analysis of ∼2000 bacterial genomes revealed that they all, without a single exception, encode one or more DNA polymerase III α-subunit (PolIIIα) homologs. Classified into C-family of DNA polymerases they come in two major forms, PolC and DnaE, related by ancient duplication. While PolC represents an evolutionary compact group, DnaE can be further subdivided into at least three groups (DnaE1-3). We performed an extensive analysis of various sequence, structure and surface properties of all four polymerase groups. Our analysis suggests a specific evolutionary pathway leading to PolC and DnaE from the last common ancestor and reveals important differences between extant polymerase groups. Among them, DnaE1 and PolC show the highest conservation of the analyzed properties. DnaE3 polymerases apparently represent an ‘impaired’ version of DnaE1. Nonessential DnaE2 polymerases, typical for oxygen-using bacteria with large GC-rich genomes, have a number of features in common with DnaE3 polymerases. The analysis of polymerase distribution in genomes revealed three major combinations: DnaE1 either alone or accompanied by one or more DnaE2s, PolC + DnaE3 and PolC + DnaE1. The first two combinations are present in Escherichia coli and Bacillus subtilis, respectively. The third one (PolC + DnaE1), found in Clostridia, represents a novel, so far experimentally uncharacterized, set.
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Affiliation(s)
- Kestutis Timinskas
- Institute of Biotechnology, Vilnius University, Graičiūno 8, Vilnius LT-02241, Lithuania
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43
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Holding AN, Lamers MH, Stephens E, Skehel JM. Hekate: software suite for the mass spectrometric analysis and three-dimensional visualization of cross-linked protein samples. J Proteome Res 2013; 12:5923-33. [PMID: 24010795 PMCID: PMC3859183 DOI: 10.1021/pr4003867] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Chemical cross-linking
of proteins combined with mass spectrometry
provides an attractive and novel method for the analysis of native
protein structures and protein complexes. Analysis of the data however
is complex. Only a small number of cross-linked peptides are produced
during sample preparation and must be identified against a background
of more abundant native peptides. To facilitate the search and identification
of cross-linked peptides, we have developed a novel software suite,
named Hekate. Hekate is a suite of tools that address the challenges
involved in analyzing protein cross-linking experiments when combined
with mass spectrometry. The software is an integrated pipeline for
the automation of the data analysis workflow and provides a novel
scoring system based on principles of linear peptide analysis. In
addition, it provides a tool for the visualization of identified cross-links
using three-dimensional models, which is particularly useful when
combining chemical cross-linking with other structural techniques.
Hekate was validated by the comparative analysis of cytochrome c (bovine heart) against previously reported data.1 Further validation was carried out on known structural
elements of DNA polymerase III, the catalytic α-subunit of the Escherichia coli DNA replisome along with new insight
into the previously uncharacterized C-terminal domain of the protein.
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Affiliation(s)
- Andrew N Holding
- MRC Laboratory of Molecular Biology , Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
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44
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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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Matsui I, Matsui E, Yamasaki K, Yokoyama H. Domain structures and inter-domain interactions defining the holoenzyme architecture of archaeal d-family DNA polymerase. Life (Basel) 2013; 3:375-85. [PMID: 25369811 PMCID: PMC4187176 DOI: 10.3390/life3030375] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/26/2013] [Accepted: 06/27/2013] [Indexed: 02/01/2023] Open
Abstract
Archaea-specific D-family DNA polymerase (PolD) forms a dimeric heterodimer consisting of two large polymerase subunits and two small exonuclease subunits. According to the protein-protein interactions identified among the domains of large and small subunits of PolD, a symmetrical model for the domain topology of the PolD holoenzyme is proposed. The experimental evidence supports various aspects of the model. The conserved amphipathic nature of the N-terminal putative α-helix of the large subunit plays a key role in the homodimeric assembly and the self-cyclization of the large subunit and is deeply involved in the archaeal PolD stability and activity. We also discuss the evolutional transformation from archaeal D-family to eukaryotic B-family polymerase on the basis of the structural information.
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Affiliation(s)
- Ikuo Matsui
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566, Japan.
| | - Eriko Matsui
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566, Japan.
| | - Kazuhiko Yamasaki
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566, Japan.
| | - Hideshi Yokoyama
- School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
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Abstract
In 1959, Arthur Kornberg was awarded the Nobel Prize for his work on the principles by which DNA is duplicated by DNA polymerases. Since then, it has been confirmed in all branches of life that replicative DNA polymerases require a single-stranded template to build a complementary strand, but they cannot start a new DNA strand de novo. Thus, they also depend on a primase, which generally assembles a short RNA primer to provide a 3'-OH that can be extended by the replicative DNA polymerase. The general principles that (1) a helicase unwinds the double-stranded DNA, (2) single-stranded DNA-binding proteins stabilize the single-stranded DNA, (3) a primase builds a short RNA primer, and (4) a clamp loader loads a clamp to (5) facilitate the loading and processivity of the replicative polymerase, are well conserved among all species. Replication of the genome is remarkably robust and is performed with high fidelity even in extreme environments. Work over the last decade or so has confirmed (6) that a common two-metal ion-promoted mechanism exists for the nucleotidyltransferase reaction that builds DNA strands, and (7) that the replicative DNA polymerases always act as a key component of larger multiprotein assemblies, termed replisomes. Furthermore (8), the integrity of replisomes is maintained by multiple protein-protein and protein-DNA interactions, many of which are inherently weak. This enables large conformational changes to occur without dissociation of replisome components, and also means that in general replisomes cannot be isolated intact.
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Affiliation(s)
- Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden.
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Lahiri I, Mukherjee P, Pata JD. Kinetic characterization of exonuclease-deficient Staphylococcus aureus PolC, a C-family replicative DNA polymerase. PLoS One 2013; 8:e63489. [PMID: 23696828 PMCID: PMC3656037 DOI: 10.1371/journal.pone.0063489] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 04/03/2013] [Indexed: 11/19/2022] Open
Abstract
PolC is the C-family replicative polymerase in low G+C content Gram-positive bacteria. To date several structures of C-family polymerases have been reported, including a high resolution crystal structure of a ternary complex of PolC with DNA and incoming deoxynucleoside triphosphate (dNTP). However, kinetic information needed to understand the enzymatic mechanism of C-family polymerases is limited. For this study we have performed a detailed steady-state and pre-steady-state kinetic characterization of correct dNTP incorporation by PolC from the Gram-positive pathogen Staphylococcus aureus, using a construct lacking both the non-conserved N-terminal domain and the 3′–5′ exonuclease domain (Sau-PolC-ΔNΔExo). We find that Sau-PolC-ΔNΔExo has a very fast catalytic rate (kpol 330 s−1) but also dissociates from DNA rapidly (koff ∼150 s−1), which explains the low processivity of PolC in the absence of sliding clamp processivity factor. Although Sau-PolC-ΔNΔExo follows the overall enzymatic pathway defined for other polymerases, some significant differences exist. The most striking feature is that the nucleotidyl transfer reaction for Sau-PolC-ΔNΔExo is reversible and is in equilibrium with dNTP binding. Simulation of the reaction pathway suggests that rate of pyrophosphate release, or a conformational change required for pyrophosphate release, is much slower than rate of bond formation. The significance of these findings is discussed in the context of previous data showing that binding of the β-clamp processivity factor stimulates the intrinsic nucleotide incorporation rate of the C-family polymerases, in addition to increasing processivity.
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Affiliation(s)
- Indrajit Lahiri
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
| | - Purba Mukherjee
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
| | - Janice D. Pata
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, New York, United States of America
- * E-mail:
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Barros T, Guenther J, Kelch B, Anaya J, Prabhakar A, O'Donnell M, Kuriyan J, Lamers MH. A structural role for the PHP domain in E. coli DNA polymerase III. BMC STRUCTURAL BIOLOGY 2013; 13:8. [PMID: 23672456 PMCID: PMC3666897 DOI: 10.1186/1472-6807-13-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 05/07/2013] [Indexed: 12/05/2022]
Abstract
Background In addition to the core catalytic machinery, bacterial replicative DNA polymerases contain a Polymerase and Histidinol Phosphatase (PHP) domain whose function is not entirely understood. The PHP domains of some bacterial replicases are active metal-dependent nucleases that may play a role in proofreading. In E. coli DNA polymerase III, however, the PHP domain has lost several metal-coordinating residues and is likely to be catalytically inactive. Results Genomic searches show that the loss of metal-coordinating residues in polymerase PHP domains is likely to have coevolved with the presence of a separate proofreading exonuclease that works with the polymerase. Although the E. coli Pol III PHP domain has lost metal-coordinating residues, the structure of the domain has been conserved to a remarkable degree when compared to that of metal-binding PHP domains. This is demonstrated by our ability to restore metal binding with only three point mutations, as confirmed by the metal-bound crystal structure of this mutant determined at 2.9 Å resolution. We also show that Pol III, a large multi-domain protein, unfolds cooperatively and that mutations in the degenerate metal-binding site of the PHP domain decrease the overall stability of Pol III and reduce its activity. Conclusions While the presence of a PHP domain in replicative bacterial polymerases is strictly conserved, its ability to coordinate metals and to perform proofreading exonuclease activity is not, suggesting additional non-enzymatic roles for the domain. Our results show that the PHP domain is a major structural element in Pol III and its integrity modulates both the stability and activity of the polymerase.
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Affiliation(s)
- Tiago Barros
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Ozawa K, Horan NP, Robinson A, Yagi H, Hill FR, Jergic S, Xu ZQ, Loscha KV, Li N, Tehei M, Oakley AJ, Otting G, Huber T, Dixon NE. Proofreading exonuclease on a tether: the complex between the E. coli DNA polymerase III subunits α, epsilon, θ and β reveals a highly flexible arrangement of the proofreading domain. Nucleic Acids Res 2013; 41:5354-67. [PMID: 23580545 PMCID: PMC3664792 DOI: 10.1093/nar/gkt162] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/18/2013] [Accepted: 02/18/2013] [Indexed: 11/24/2022] Open
Abstract
A complex of the three (αεθ) core subunits and the β2 sliding clamp is responsible for DNA synthesis by Pol III, the Escherichia coli chromosomal DNA replicase. The 1.7 Å crystal structure of a complex between the PHP domain of α (polymerase) and the C-terminal segment of ε (proofreading exonuclease) subunits shows that ε is attached to α at a site far from the polymerase active site. Both α and ε contain clamp-binding motifs (CBMs) that interact simultaneously with β2 in the polymerization mode of DNA replication by Pol III. Strengthening of both CBMs enables isolation of stable αεθ:β2 complexes. Nuclear magnetic resonance experiments with reconstituted αεθ:β2 demonstrate retention of high mobility of a segment of 22 residues in the linker that connects the exonuclease domain of ε with its α-binding segment. In spite of this, small-angle X-ray scattering data show that the isolated complex with strengthened CBMs has a compact, but still flexible, structure. Photo-crosslinking with p-benzoyl-L-phenylalanine incorporated at different sites in the α-PHP domain confirm the conformational variability of the tether. Structural models of the αεθ:β2 replicase complex with primer-template DNA combine all available structural data.
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Affiliation(s)
- Kiyoshi Ozawa
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Nicholas P. Horan
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Andrew Robinson
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Hiromasa Yagi
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Flynn R. Hill
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Slobodan Jergic
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Zhi-Qiang Xu
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Karin V. Loscha
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Nan Li
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Moeava Tehei
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Aaron J. Oakley
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Gottfried Otting
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Thomas Huber
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
| | - Nicholas E. Dixon
- School of Chemistry, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia and Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
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50
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Rannou O, Le Chatelier E, Larson MA, Nouri H, Dalmais B, Laughton C, Jannière L, Soultanas P. Functional interplay of DnaE polymerase, DnaG primase and DnaC helicase within a ternary complex, and primase to polymerase hand-off during lagging strand DNA replication in Bacillus subtilis. Nucleic Acids Res 2013; 41:5303-20. [PMID: 23563155 PMCID: PMC3664799 DOI: 10.1093/nar/gkt207] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Bacillus subtilis has two replicative DNA polymerases. PolC is a processive high-fidelity replicative polymerase, while the error-prone DnaEBs extends RNA primers before hand-off to PolC at the lagging strand. We show that DnaEBs interacts with the replicative helicase DnaC and primase DnaG in a ternary complex. We characterize their activities and analyse the functional significance of their interactions using primase, helicase and primer extension assays, and a ‘stripped down’ reconstituted coupled assay to investigate the coordinated displacement of the parental duplex DNA at a replication fork, synthesis of RNA primers along the lagging strand and hand-off to DnaEBs. The DnaG–DnaEBs hand-off takes place after de novo polymerization of only two ribonucleotides by DnaG, and does not require other replication proteins. Furthermore, the fidelity of DnaEBs is improved by DnaC and DnaG, likely via allosteric effects induced by direct protein–protein interactions that lower the efficiency of nucleotide mis-incorporations and/or the efficiency of extension of mis-aligned primers in the catalytic site of DnaEBs. We conclude that de novo RNA primer synthesis by DnaG and initial primer extension by DnaEBs are carried out by a lagging strand–specific subcomplex comprising DnaG, DnaEBs and DnaC, which stimulates chromosomal replication with enhanced fidelity.
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Affiliation(s)
- Olivier Rannou
- Centre for Biomolecular Sciences, School of Chemistry, University Park, University of Nottingham, Nottingham NG7 2RD, UK
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