1
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Zakharova K, Liu M, Greenwald JR, Caldwell BC, Qi Z, Wysocki VH, Bell CE. Structural Basis for the Interaction of Redβ Single-Strand Annealing Protein with Escherichia coli Single-Stranded DNA-Binding Protein. J Mol Biol 2024; 436:168590. [PMID: 38663547 DOI: 10.1016/j.jmb.2024.168590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/07/2024]
Abstract
Redβ is a protein from bacteriophage λ that binds to single-stranded DNA (ssDNA) to promote the annealing of complementary strands. Together with λ-exonuclease (λ-exo), Redβ is part of a two-component DNA recombination system involved in multiple aspects of genome maintenance. The proteins have been exploited in powerful methods for bacterial genome engineering in which Redβ can anneal an electroporated oligonucleotide to a complementary target site at the lagging strand of a replication fork. Successful annealing in vivo requires the interaction of Redβ with E. coli single-stranded DNA-binding protein (SSB), which coats the ssDNA at the lagging strand to coordinate access of numerous replication proteins. Previous mutational analysis revealed that the interaction between Redβ and SSB involves the C-terminal domain (CTD) of Redβ and the C-terminal tail of SSB (SSB-Ct), the site for binding of numerous host proteins. Here, we have determined the x-ray crystal structure of Redβ CTD in complex with a peptide corresponding to the last nine residues of SSB (MDFDDDIPF). Formation of the complex is predominantly mediated by hydrophobic interactions between two phenylalanine side chains of SSB (Phe-171 and Phe-177) and an apolar groove on the CTD, combined with electrostatic interactions between the C-terminal carboxylate of SSB and Lys-214 of the CTD. Mutation of any of these residues to alanine significantly disrupts the interaction of full-length Redβ and SSB proteins. Structural knowledge of this interaction will help to expand the utility of Redβ-mediated recombination to a wider range of bacterial hosts for applications in synthetic biology.
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Affiliation(s)
- Katerina Zakharova
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
| | - Mengqi Liu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
| | - Jacelyn R Greenwald
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Brian C Caldwell
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA; Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
| | - Zihao Qi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Vicki H Wysocki
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Charles E Bell
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA; Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA; Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
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2
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Bonde NJ, Kozlov AG, Cox MM, Lohman TM, Keck JL. Molecular insights into the prototypical single-stranded DNA-binding protein from E. coli. Crit Rev Biochem Mol Biol 2024; 59:99-127. [PMID: 38770626 PMCID: PMC11209772 DOI: 10.1080/10409238.2024.2330372] [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: 11/28/2023] [Accepted: 03/11/2024] [Indexed: 05/22/2024]
Abstract
The SSB protein of Escherichia coli functions to bind single-stranded DNA wherever it occurs during DNA metabolism. Depending upon conditions, SSB occurs in several different binding modes. In the course of its function, SSB diffuses on ssDNA and transfers rapidly between different segments of ssDNA. SSB interacts with many other proteins involved in DNA metabolism, with 22 such SSB-interacting proteins, or SIPs, defined to date. These interactions chiefly involve the disordered and conserved C-terminal residues of SSB. When not bound to ssDNA, SSB can aggregate to form a phase-separated biomolecular condensate. Current understanding of the properties of SSB and the functional significance of its many intermolecular interactions are summarized in this review.
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Affiliation(s)
- Nina J. Bonde
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Alexander G. Kozlov
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Michael M. Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Timothy M. Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - James L. Keck
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
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3
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Xiao Y, Jiang Z, Zhang M, Zhang X, Gan Q, Yang Y, Wu P, Feng X, Ni J, Dong X, She Q, Huang Q, Shen Y. The canonical single-stranded DNA-binding protein is not an essential replication factor but an RNA chaperon in Saccharolobus islandicus. iScience 2023; 26:108389. [PMID: 38034349 PMCID: PMC10684826 DOI: 10.1016/j.isci.2023.108389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/28/2023] [Accepted: 11/01/2023] [Indexed: 12/02/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) have been regarded as indispensable replication factors. Herein, we report that the genes encoding the canonical SSB (SisSSB) and the non-canonical SSB (SisDBP) in Saccharolobus islandicus REY15A are not essential for cell viability. Interestingly, at a lower temperature (55°C), the protein level of SisSSB increases and the growth of ΔSisssb and ΔSisssbΔSisdbp is retarded. SisSSB exhibits melting activity on dsRNA and DNA/RNA hybrid in vitro and is able to melt RNA hairpin in Escherichia coli. Furthermore, the core SisSSB domain is able to complement the absence of cold-shock proteins in E. coli. Importantly, these activities are conserved in the canonical SSBs from Crenarchaeota species that lack bacterial Csp homologs. Overall, our study has clarified the function of the archaeal canonical SSBs which do not function as a DNA-processing factor, but play a role in the processes requiring melting of dsRNA or DNA/RNA hybrid.
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Affiliation(s)
- Yuanxi Xiao
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Zhichao Jiang
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Mengqi Zhang
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Xuemei Zhang
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Qi Gan
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Yunfeng Yang
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Pengju Wu
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Xu Feng
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Jinfeng Ni
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Xiuzhu Dong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qunxin She
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Qihong Huang
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
| | - Yulong Shen
- CRISPR and Archaea Biology Research Center, State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao 266237, China
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4
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Pham P, Wood EA, Cox MM, Goodman MF. RecA and SSB genome-wide distribution in ssDNA gaps and ends in Escherichia coli. Nucleic Acids Res 2023; 51:5527-5546. [PMID: 37070184 PMCID: PMC10287960 DOI: 10.1093/nar/gkad263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 03/29/2023] [Accepted: 03/30/2023] [Indexed: 04/19/2023] Open
Abstract
Single-stranded DNA (ssDNA) gapped regions are common intermediates in DNA transactions. Using a new non-denaturing bisulfite treatment combined with ChIP-seq, abbreviated 'ssGap-seq', we explore RecA and SSB binding to ssDNA on a genomic scale in E. coli in a wide range of genetic backgrounds. Some results are expected. During log phase growth, RecA and SSB assembly profiles coincide globally, concentrated on the lagging strand and enhanced after UV irradiation. Unexpected results also abound. Near the terminus, RecA binding is favored over SSB, binding patterns change in the absence of RecG, and the absence of XerD results in massive RecA assembly. RecA may substitute for the absence of XerCD to resolve chromosome dimers. A RecA loading pathway may exist that is independent of RecBCD and RecFOR. Two prominent and focused peaks of RecA binding revealed a pair of 222 bp and GC-rich repeats, equidistant from dif and flanking the Ter domain. The repeats, here named RRS for replication risk sequence, trigger a genomically programmed generation of post-replication gaps that may play a special role in relieving topological stress during replication termination and chromosome segregation. As demonstrated here, ssGap-seq provides a new window on previously inaccessible aspects of ssDNA metabolism.
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Affiliation(s)
- Phuong Pham
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089-2910, USA
| | - Elizabeth A Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
| | - Myron F Goodman
- Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089-2910, USA
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5
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Radford HM, Toft CJ, Sorenson AE, Schaeffer PM. Inhibition of Replication Fork Formation and Progression: Targeting the Replication Initiation and Primosomal Proteins. Int J Mol Sci 2023; 24:ijms24108802. [PMID: 37240152 DOI: 10.3390/ijms24108802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/02/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
Over 1.2 million deaths are attributed to multi-drug-resistant (MDR) bacteria each year. Persistence of MDR bacteria is primarily due to the molecular mechanisms that permit fast replication and rapid evolution. As many pathogens continue to build resistance genes, current antibiotic treatments are being rendered useless and the pool of reliable treatments for many MDR-associated diseases is thus shrinking at an alarming rate. In the development of novel antibiotics, DNA replication is still a largely underexplored target. This review summarises critical literature and synthesises our current understanding of DNA replication initiation in bacteria with a particular focus on the utility and applicability of essential initiation proteins as emerging drug targets. A critical evaluation of the specific methods available to examine and screen the most promising replication initiation proteins is provided.
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Affiliation(s)
- Holly M Radford
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia
| | - Casey J Toft
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia
| | - Alanna E Sorenson
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia
| | - Patrick M Schaeffer
- Molecular and Cell Biology, College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, QLD 4811, Australia
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6
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Newcomb ESP, Douma LG, Morris LA, Bloom LB. The Escherichia coli clamp loader rapidly remodels SSB on DNA to load clamps. Nucleic Acids Res 2022; 50:12872-12884. [PMID: 36511874 PMCID: PMC9825162 DOI: 10.1093/nar/gkac1169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022] Open
Abstract
Single-stranded DNA binding proteins (SSBs) avidly bind ssDNA and yet enzymes that need to act during DNA replication and repair are not generally impeded by SSB, and are often stimulated by SSB. Here, the effects of Escherichia coli SSB on the activities of the DNA polymerase processivity clamp loader were investigated. SSB enhances binding of the clamp loader to DNA by increasing the lifetime on DNA. Clamp loading was measured on DNA substrates that differed in length of ssDNA overhangs to permit SSB binding in different binding modes. Even though SSB binds DNA adjacent to single-stranded/double-stranded DNA junctions where clamps are loaded, the rate of clamp loading on DNA was not affected by SSB on any of the DNA substrates. Direct measurements of the relative timing of DNA-SSB remodeling and enzyme-DNA binding showed that the clamp loader rapidly remodels SSB on DNA such that SSB has little effect on DNA binding rates. However, when SSB was mutated to reduce protein-protein interactions with the clamp loader, clamp loading was inhibited by impeding binding of the clamp loader to DNA. Thus, protein-protein interactions between the clamp loader and SSB facilitate rapid DNA-SSB remodeling to allow rapid clamp loader-DNA binding and clamp loading.
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Affiliation(s)
- Elijah S P Newcomb
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610-0245, USA
| | - Lauren G Douma
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610-0245, USA
| | - Leslie A Morris
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610-0245, USA
| | - Linda B Bloom
- To whom correspondence should be addressed. Tel: +1 352 294 8379; Fax: +1 352 392 2953;
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7
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Ariga K, Tashiro M. Change in the graphics of journal articles in the life sciences field: analysis of figures and tables in the journal "Cell". HISTORY AND PHILOSOPHY OF THE LIFE SCIENCES 2022; 44:33. [PMID: 35918565 PMCID: PMC9345845 DOI: 10.1007/s40656-022-00516-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 06/17/2022] [Indexed: 05/03/2023]
Abstract
The purpose of this study is to examine how trends in the use of images in modern life science journals have changed since the spread of computer-based visual and imaging technology. To this end, a new classification system was constructed to analyze how the graphics of a scientific journal have changed over the years. The focus was on one international peer-reviewed journal in life sciences, Cell, which was founded in 1974, whereby 1725 figures and 160 tables from the research articles in Cell were sampled. The unit of classification was defined as a graphic and the figures and tables were divided into 5952 graphics. These graphics were further classified into hierarchical categories, and the data in each category were aggregated every five years. The following categories were observed: (1) data graphics, (2) explanation graphics, and (3) hybrid graphics. Data graphics increased by more than sixfold between 1974 and 2014, and some types of data graphics including mechanical reproduction images and bar charts displayed notable changes. The representation of explanatory graphics changed from hand-painted illustrations to diagrams of Bezier-curves. It is suggested that in addition to the development of experimental technologies such as fluorescent microscopy and big data analysis, continuously evolving application software for image creation and researchers' motivation to convince reviewers and editors have influenced these changes.
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Affiliation(s)
- Kana Ariga
- Division of Cyclotron Nuclear Medicine, Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan.
- LAIMAN, Inc., Tokyo, Japan.
- College of Arts and Sciences, J. F. Oberlin University, Tokyo, Japan.
| | - Manabu Tashiro
- Division of Cyclotron Nuclear Medicine, Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
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8
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The combined DNA and RNA synthetic capabilities of archaeal DNA primase facilitate primer hand-off to the replicative DNA polymerase. Nat Commun 2022; 13:433. [PMID: 35064114 PMCID: PMC8782868 DOI: 10.1038/s41467-022-28093-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 01/10/2022] [Indexed: 11/25/2022] Open
Abstract
Replicative DNA polymerases cannot initiate DNA synthesis de novo and rely on dedicated RNA polymerases, primases, to generate a short primer. This primer is then extended by the DNA polymerase. In diverse archaeal species, the primase has long been known to have the ability to synthesize both RNA and DNA. However, the relevance of these dual nucleic acid synthetic modes for productive primer synthesis has remained enigmatic. In the current work, we reveal that the ability of primase to polymerize DNA serves dual roles in promoting the hand-off of the primer to the replicative DNA polymerase holoenzyme. First, it creates a 5′-RNA-DNA-3′ hybrid primer which serves as an optimal substrate for elongation by the replicative DNA polymerase. Second, it promotes primer release by primase. Furthermore, modeling and experimental data indicate that primase incorporates a deoxyribonucleotide stochastically during elongation and that this switches the primase into a dedicated DNA synthetic mode polymerase. DNA primases initiate a short primer before handing off to DNA polymerases to continue replication. Here the authors reveal a unique ability of archaeal primases to first synthesize RNA before stochastically incorporating a deoxyribonucleotide and further extending the primer as DNA.
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9
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The alarmone (p)ppGpp regulates primer extension by bacterial primase. J Mol Biol 2021; 433:167189. [PMID: 34389317 DOI: 10.1016/j.jmb.2021.167189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/22/2021] [Accepted: 08/02/2021] [Indexed: 11/21/2022]
Abstract
Primase is an essential component of the DNA replication machinery, responsible for synthesizing RNA primers that initiate leading and lagging strand DNA synthesis. Bacterial primase activity can be regulated by the starvation-inducible nucleotide (p)ppGpp. This regulation contributes to a timely inhibition of DNA replication upon amino acid starvation in the Gram-positive bacterium Bacillus subtilis. Here, we characterize the effect of (p)ppGpp on B. subtilis DnaG primase activity in vitro. Using a single-nucleotide resolution primase assay, we dissected the effect of ppGpp on the initiation, extension, and fidelity of B. subtilis primase. We found that ppGpp has a mild effect on initiation, but strongly inhibits primer extension and reduces primase processivity, promoting termination of primer extension. High (p)ppGpp concentration, together with low GTP concentration, additively inhibit primase activity. This explains the strong inhibition of replication elongation during starvation which induces high levels of (p)ppGpp and depletion of GTP in B. subtilis. Finally, we found that lowering GTP concentration results in mismatches in primer base pairing that allow priming readthrough, and that ppGpp reduces readthrough to protect priming fidelity. These results highlight the importance of (p)ppGpp in protecting replisome integrity and genome stability in fluctuating nucleotide concentrations upon onset of environmental stress.
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10
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Shinn MK, Kozlov AG, Lohman TM. Allosteric effects of SSB C-terminal tail on assembly of E. coli RecOR proteins. Nucleic Acids Res 2021; 49:1987-2004. [PMID: 33450019 PMCID: PMC7913777 DOI: 10.1093/nar/gkaa1291] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 12/21/2020] [Accepted: 12/28/2020] [Indexed: 01/21/2023] Open
Abstract
Escherichia coli RecO is a recombination mediator protein that functions in the RecF pathway of homologous recombination, in concert with RecR, and interacts with E. coli single stranded (ss) DNA binding (SSB) protein via the last 9 amino acids of the C-terminal tails (SSB-Ct). Structures of the E. coli RecR and RecOR complexes are unavailable; however, crystal structures from other organisms show differences in RecR oligomeric state and RecO stoichiometry. We report analytical ultracentrifugation studies of E. coli RecR assembly and its interaction with RecO for a range of solution conditions using both sedimentation velocity and equilibrium approaches. We find that RecR exists in a pH-dependent dimer-tetramer equilibrium that explains the different assembly states reported in previous studies. RecO binds with positive cooperativity to a RecR tetramer, forming both RecR4O and RecR4O2 complexes. We find no evidence of a stable RecO complex with RecR dimers. However, binding of RecO to SSB-Ct peptides elicits an allosteric effect, eliminating the positive cooperativity and shifting the equilibrium to favor a RecR4O complex. These studies suggest a mechanism for how SSB binding to RecO influences the distribution of RecOR complexes to facilitate loading of RecA onto SSB coated ssDNA to initiate homologous recombination.
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Affiliation(s)
- Min Kyung Shinn
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA.,Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alexander G Kozlov
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Timothy M Lohman
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
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11
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Sutera VA, Weeks SJ, Dudenhausen EE, Baggett HBR, Shaw MC, Brand KA, Glass DJ, Bloom LB, Lovett ST. Alternative complexes formed by the Escherichia coli clamp loader accessory protein HolC (x) with replication protein HolD (ψ) and repair protein YoaA. DNA Repair (Amst) 2021; 100:103006. [PMID: 33582602 DOI: 10.1016/j.dnarep.2020.103006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 10/26/2020] [Accepted: 10/29/2020] [Indexed: 10/22/2022]
Abstract
Efficient and faithful replication of DNA is essential for all organisms. However, the replication fork frequently encounters barriers that need to be overcome to ensure cell survival and genetic stability. Cells must carefully balance and regulate replication vs. repair reactions. In Escherichia coli, the replisome consists of the DNA polymerase III holoenzyme, including DNA polymerase, proofreading exonuclease, processivity clamp and clamp loader, as well as a fork helicase, DnaB and primase, DnaG. We provide evidence here that one component of the clamp loader complex, HolC (or χ) plays a dual role via its ability to form 2 mutually exclusive complexes: one with HolD (or ψ) that recruits the clamp-loader and hence the DNA polymerase holoenzyme and another with helicase-like YoaA protein, a DNA-damage inducible repair protein. By yeast 2 hybrid analysis, we show that two residues of HolC, F64 and W57, at the interface in the structure with HolD, are required for interaction with HolD and for interaction with YoaA. Mutation of these residues does not interfere with HolC's interaction with single-strand DNA binding protein, SSB. In vivo, these mutations fail to complement the poor growth and sensitivity to azidothymidine, a chain-terminating replication inhibitor. In support of the notion that these are exclusive complexes, co-expression of HolC, HolD and YoaA, followed by pulldown of YoaA, yields a complex with HolC but not HolD. YoaA fails to pulldown HolC-F64A. We hypothesize that HolC, by binding with SSB, can recruit the DNA polymerase III holoenzyme through HolD, or an alternative repair complex with YoaA helicase.
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Affiliation(s)
- Vincent A Sutera
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, MS029, 415 South St., Waltham, MA, 02453, United States
| | - Savannah J Weeks
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610-0245, United States
| | - Elizabeth E Dudenhausen
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610-0245, United States
| | - Helen B Rappe Baggett
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, MS029, 415 South St., Waltham, MA, 02453, United States
| | - McKay C Shaw
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, MS029, 415 South St., Waltham, MA, 02453, United States
| | - Kirsten A Brand
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, MS029, 415 South St., Waltham, MA, 02453, United States
| | - David J Glass
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, MS029, 415 South St., Waltham, MA, 02453, United States
| | - Linda B Bloom
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, 32610-0245, United States
| | - Susan T Lovett
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, MS029, 415 South St., Waltham, MA, 02453, United States.
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12
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Pérez-Arnaiz P, Dattani A, Smith V, Allers T. Haloferax volcanii-a model archaeon for studying DNA replication and repair. Open Biol 2020; 10:200293. [PMID: 33259746 PMCID: PMC7776575 DOI: 10.1098/rsob.200293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/09/2020] [Indexed: 12/16/2022] Open
Abstract
The tree of life shows the relationship between all organisms based on their common ancestry. Until 1977, it comprised two major branches: prokaryotes and eukaryotes. Work by Carl Woese and other microbiologists led to the recategorization of prokaryotes and the proposal of three primary domains: Eukarya, Bacteria and Archaea. Microbiological, genetic and biochemical techniques were then needed to study the third domain of life. Haloferax volcanii, a halophilic species belonging to the phylum Euryarchaeota, has provided many useful tools to study Archaea, including easy culturing methods, genetic manipulation and phenotypic screening. This review will focus on DNA replication and DNA repair pathways in H. volcanii, how this work has advanced our knowledge of archaeal cellular biology, and how it may deepen our understanding of bacterial and eukaryotic processes.
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Affiliation(s)
| | | | | | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
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13
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Julius C, Salgado PS, Yuzenkova Y. Metabolic cofactors NADH and FAD act as non-canonical initiating substrates for a primase and affect replication primer processing in vitro. Nucleic Acids Res 2020; 48:7298-7306. [PMID: 32463447 PMCID: PMC7367122 DOI: 10.1093/nar/gkaa447] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 11/17/2022] Open
Abstract
To initiate replication on a double-stranded DNA de novo, all organisms require primase, an RNA polymerase making short RNA primers which are then extended by DNA polymerases. Here, we show that primase can use metabolic cofactors as initiating substrates, instead of its canonical substrate ATP. DnaG primase of Escherichia coli initiates synthesis of RNA with NADH (the reduced form of nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) in vitro. These cofactors consist of an ADP core covalently bound to extra moieties. The ADP component of these metabolites base-pairs with the DNA template and provides a 3′-OH group for RNA extension. The additional cofactors moieties apparently contact the ‘basic ridge’ domain of DnaG, but not the DNA template base at the –1 position. ppGpp, the starvation response regulator, strongly inhibits the initiation with cofactors, hypothetically due to competition for overlapping binding sites. Efficient RNA primer processing is a prerequisite for Okazaki fragments maturation, and we find that the efficiency of primer processing by DNA polymerase I in vitro is specifically affected by the cofactors on its 5′-end. Together these results indicate that utilization of cofactors as substrates by primase may influence regulation of replication initiation and Okazaki fragments processing.
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Affiliation(s)
- Christina Julius
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle upon Tyne, NE2 4AX, UK
| | - Paula S Salgado
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle upon Tyne, NE2 4AX, UK
| | - Yulia Yuzenkova
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle upon Tyne, NE2 4AX, UK
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14
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Monachino E, Jergic S, Lewis JS, Xu ZQ, Lo ATY, O'Shea VL, Berger JM, Dixon NE, van Oijen AM. A Primase-Induced Conformational Switch Controls the Stability of the Bacterial Replisome. Mol Cell 2020; 79:140-154.e7. [PMID: 32464091 DOI: 10.1016/j.molcel.2020.04.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 03/12/2020] [Accepted: 04/20/2020] [Indexed: 12/16/2022]
Abstract
Recent studies of bacterial DNA replication have led to a picture of the replisome as an entity that freely exchanges DNA polymerases and displays intermittent coupling between the helicase and polymerase(s). Challenging the textbook model of the polymerase holoenzyme acting as a stable complex coordinating the replisome, these observations suggest a role of the helicase as the central organizing hub. We show here that the molecular origin of this newly found plasticity lies in the 500-fold increase in strength of the interaction between the polymerase holoenzyme and the replicative helicase upon association of the primase with the replisome. By combining in vitro ensemble-averaged and single-molecule assays, we demonstrate that this conformational switch operates during replication and promotes recruitment of multiple holoenzymes at the fork. Our observations provide a molecular mechanism for polymerase exchange and offer a revised model for the replication reaction that emphasizes its stochasticity.
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Affiliation(s)
- Enrico Monachino
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; Zernike Institute for Advanced Materials, University of Groningen, Groningen 9747, the Netherlands
| | - Slobodan Jergic
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Jacob S Lewis
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Zhi-Qiang Xu
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Allen T Y Lo
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Valerie L O'Shea
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - James M Berger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nicholas E Dixon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
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15
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Shinn MK, Kozlov AG, Nguyen B, Bujalowski WM, Lohman TM. Are the intrinsically disordered linkers involved in SSB binding to accessory proteins? Nucleic Acids Res 2019; 47:8581-8594. [PMID: 31329947 PMCID: PMC7145534 DOI: 10.1093/nar/gkz606] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 06/28/2019] [Accepted: 07/05/2019] [Indexed: 11/16/2022] Open
Abstract
Escherichia coli single strand (ss) DNA binding (SSB) protein protects ssDNA intermediates and recruits at least 17 SSB interacting proteins (SIPs) during genome maintenance. The SSB C-termini contain a 9 residue acidic tip and a 56 residue intrinsically disordered linker (IDL). The acidic tip interacts with SIPs; however a recent proposal suggests that the IDL may also interact with SIPs. Here we examine the binding to four SIPs (RecO, PriC, PriA and χ subunit of DNA polymerase III) of three peptides containing the acidic tip and varying amounts of the IDL. Independent of IDL length, we find no differences in peptide binding to each individual SIP indicating that binding is due solely to the acidic tip. However, the tip shows specificity, with affinity decreasing in the order: RecO > PriA ∼ χ > PriC. Yet, RecO binding to the SSB tetramer and an SSB–ssDNA complex show significant thermodynamic differences compared to the peptides alone, suggesting that RecO interacts with another region of SSB, although not the IDL. SSB containing varying IDL deletions show different binding behavior, with the larger linker deletions inhibiting RecO binding, likely due to increased competition between the acidic tip interacting with DNA binding sites within SSB.
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Affiliation(s)
- Min Kyung Shinn
- Department of Biochemistry and Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA.,Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alexander G Kozlov
- Department of Biochemistry and Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Binh Nguyen
- Department of Biochemistry and Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
| | - Wlodek M Bujalowski
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Timothy M Lohman
- Department of Biochemistry and Biophysics, Washington University in St. Louis School of Medicine, St. Louis, MO 63110, USA
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16
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Spenkelink LM, Lewis JS, Jergic S, Xu ZQ, Robinson A, Dixon NE, van Oijen AM. Recycling of single-stranded DNA-binding protein by the bacterial replisome. Nucleic Acids Res 2019; 47:4111-4123. [PMID: 30767010 PMCID: PMC6486552 DOI: 10.1093/nar/gkz090] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/30/2019] [Accepted: 02/09/2019] [Indexed: 02/06/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) support DNA replication by protecting single-stranded DNA from nucleolytic attack, preventing intra-strand pairing events and playing many other regulatory roles within the replisome. Recent developments in single-molecule approaches have led to a revised picture of the replisome that is much more complex in how it retains or recycles protein components. Here, we visualize how an in vitro reconstituted Escherichia coli replisome recruits SSB by relying on two different molecular mechanisms. Not only does it recruit new SSB molecules from solution to coat newly formed single-stranded DNA on the lagging strand, but it also internally recycles SSB from one Okazaki fragment to the next. We show that this internal transfer mechanism is balanced against recruitment from solution in a manner that is concentration dependent. By visualizing SSB dynamics in live cells, we show that both internal transfer and external exchange mechanisms are physiologically relevant.
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Affiliation(s)
- Lisanne M Spenkelink
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia.,Zernike Institute for Advanced Materials, University of Groningen, Groningen, 9747 AG, the Netherlands
| | - Jacob S Lewis
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Slobodan Jergic
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Zhi-Qiang Xu
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Andrew Robinson
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.,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, Wollongong, New South Wales 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
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17
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Mallam AL, Sae-Lee W, Schaub JM, Tu F, Battenhouse A, Jang YJ, Kim J, Wallingford JB, Finkelstein IJ, Marcotte EM, Drew K. Systematic Discovery of Endogenous Human Ribonucleoprotein Complexes. Cell Rep 2019; 29:1351-1368.e5. [PMID: 31665645 PMCID: PMC6873818 DOI: 10.1016/j.celrep.2019.09.060] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 08/30/2019] [Accepted: 09/18/2019] [Indexed: 12/16/2022] Open
Abstract
RNA-binding proteins (RBPs) play essential roles in biology and are frequently associated with human disease. Although recent studies have systematically identified individual RNA-binding proteins, their higher-order assembly into ribonucleoprotein (RNP) complexes has not been systematically investigated. Here, we describe a proteomics method for systematic identification of RNP complexes in human cells. We identify 1,428 protein complexes that associate with RNA, indicating that more than 20% of known human protein complexes contain RNA. To explore the role of RNA in the assembly of each complex, we identify complexes that dissociate, change composition, or form stable protein-only complexes in the absence of RNA. We use our method to systematically identify cell-type-specific RNA-associated proteins in mouse embryonic stem cells and finally, distribute our resource, rna.MAP, in an easy-to-use online interface (rna.proteincomplexes.org). Our system thus provides a methodology for explorations across human tissues, disease states, and throughout all domains of life.
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Affiliation(s)
- Anna L Mallam
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
| | - Wisath Sae-Lee
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Jeffrey M Schaub
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Fan Tu
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Anna Battenhouse
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Yu Jin Jang
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jonghwan Kim
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - John B Wallingford
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Edward M Marcotte
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
| | - Kevin Drew
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
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18
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Bogutzki A, Naue N, Litz L, Pich A, Curth U. E. coli primase and DNA polymerase III holoenzyme are able to bind concurrently to a primed template during DNA replication. Sci Rep 2019; 9:14460. [PMID: 31595021 PMCID: PMC6783573 DOI: 10.1038/s41598-019-51031-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 09/24/2019] [Indexed: 11/15/2022] Open
Abstract
During DNA replication in E. coli, a switch between DnaG primase and DNA polymerase III holoenzyme (pol III) activities has to occur every time when the synthesis of a new Okazaki fragment starts. As both primase and the χ subunit of pol III interact with the highly conserved C-terminus of single-stranded DNA-binding protein (SSB), it had been proposed that the binding of both proteins to SSB is mutually exclusive. Using a replication system containing the origin of replication of the single-stranded DNA phage G4 (G4ori) saturated with SSB, we tested whether DnaG and pol III can bind concurrently to the primed template. We found that the addition of pol III does not lead to a displacement of primase, but to the formation of higher complexes. Even pol III-mediated primer elongation by one or several DNA nucleotides does not result in the dissociation of DnaG. About 10 nucleotides have to be added in order to displace one of the two primase molecules bound to SSB-saturated G4ori. The concurrent binding of primase and pol III is highly plausible, since even the SSB tetramer situated directly next to the 3′-terminus of the primer provides four C-termini for protein-protein interactions.
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Affiliation(s)
- Andrea Bogutzki
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, 30625, Carl-Neuberg-Str. 1, Germany
| | - Natalie Naue
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, 30625, Carl-Neuberg-Str. 1, Germany.,Inamed GmbH, Gauting, 82131, Germany
| | - Lidia Litz
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, 30625, Carl-Neuberg-Str. 1, Germany
| | - Andreas Pich
- Institute for Toxicology, Hannover Medical School, Hannover, 30625, Carl-Neuberg-Str. 1, Germany
| | - Ute Curth
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, 30625, Carl-Neuberg-Str. 1, Germany.
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19
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Ilic S, Cohen S, Singh M, Tam B, Dayan A, Akabayov B. DnaG Primase-A Target for the Development of Novel Antibacterial Agents. Antibiotics (Basel) 2018; 7:E72. [PMID: 30104489 PMCID: PMC6163395 DOI: 10.3390/antibiotics7030072] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/06/2018] [Accepted: 08/09/2018] [Indexed: 12/21/2022] Open
Abstract
The bacterial primase-an essential component in the replisome-is a promising but underexploited target for novel antibiotic drugs. Bacterial primases have a markedly different structure than the human primase. Inhibition of primase activity is expected to selectively halt bacterial DNA replication. Evidence is growing that halting DNA replication has a bacteriocidal effect. Therefore, inhibitors of DNA primase could provide antibiotic agents. Compounds that inhibit bacterial DnaG primase have been developed using different approaches. In this paper, we provide an overview of the current literature on DNA primases as novel drug targets and the methods used to find their inhibitors. Although few inhibitors have been identified, there are still challenges to develop inhibitors that can efficiently halt DNA replication and may be applied in a clinical setting.
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Affiliation(s)
- Stefan Ilic
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
| | - Shira Cohen
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
| | - Meenakshi Singh
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
| | - Benjamin Tam
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
| | - Adi Dayan
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
| | - Barak Akabayov
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
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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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Chilingaryan Z, Headey SJ, Lo ATY, Xu ZQ, Otting G, Dixon NE, Scanlon MJ, Oakley AJ. Fragment-Based Discovery of Inhibitors of the Bacterial DnaG-SSB Interaction. Antibiotics (Basel) 2018; 7:E14. [PMID: 29470422 PMCID: PMC5872125 DOI: 10.3390/antibiotics7010014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 02/09/2018] [Accepted: 02/13/2018] [Indexed: 12/30/2022] Open
Abstract
In bacteria, the DnaG primase is responsible for synthesis of short RNA primers used to initiate chain extension by replicative DNA polymerase(s) during chromosomal replication. Among the proteins with which Escherichia coli DnaG interacts is the single-stranded DNA-binding protein, SSB. The C-terminal hexapeptide motif of SSB (DDDIPF; SSB-Ct) is highly conserved and is known to engage in essential interactions with many proteins in nucleic acid metabolism, including primase. Here, fragment-based screening by saturation-transfer difference nuclear magnetic resonance (STD-NMR) and surface plasmon resonance assays identified inhibitors of the primase/SSB-Ct interaction. Hits were shown to bind to the SSB-Ct-binding site using 15N-¹H HSQC spectra. STD-NMR was used to demonstrate binding of one hit to other SSB-Ct binding partners, confirming the possibility of simultaneous inhibition of multiple protein/SSB interactions. The fragment molecules represent promising scaffolds on which to build to discover new antibacterial compounds.
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Affiliation(s)
- Zorik Chilingaryan
- Molecular Horizons and School of Chemistry, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
| | - Stephen J Headey
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.
| | - Allen T Y Lo
- Molecular Horizons and School of Chemistry, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
| | - Zhi-Qiang Xu
- Molecular Horizons and School of Chemistry, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
| | - Gottfried Otting
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia.
| | - Nicholas E Dixon
- Molecular Horizons and School of Chemistry, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
| | - Martin J Scanlon
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.
| | - Aaron J Oakley
- Molecular Horizons and School of Chemistry, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia.
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22
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Scherr MJ, Safaric B, Duderstadt KE. Noise in the Machine: Alternative Pathway Sampling is the Rule During DNA Replication. Bioessays 2017; 40. [PMID: 29282758 DOI: 10.1002/bies.201700159] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 12/01/2017] [Indexed: 11/07/2022]
Abstract
The astonishing efficiency and accuracy of DNA replication has long suggested that refined rules enforce a single highly reproducible sequence of molecular events during the process. This view was solidified by early demonstrations that DNA unwinding and synthesis are coupled within a stable molecular factory, known as the replisome, which consists of conserved components that each play unique and complementary roles. However, recent single-molecule observations of replisome dynamics have begun to challenge this view, revealing that replication may not be defined by a uniform sequence of events. Instead, multiple exchange pathways, pauses, and DNA loop types appear to dominate replisome function. These observations suggest we must rethink our fundamental assumptions and acknowledge that each replication cycle may involve sampling of alternative, sometimes parallel, pathways. Here, we review our current mechanistic understanding of DNA replication while highlighting findings that exemplify multi-pathway aspects of replisome function and considering the broader implications.
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Affiliation(s)
- Matthias J Scherr
- Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Barbara Safaric
- Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Karl E Duderstadt
- Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, Martinsried, Germany.,Physik Department, Technische Universität München, Garching, Germany
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23
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Seco EM, Ayora S. Bacillus subtilis DNA polymerases, PolC and DnaE, are required for both leading and lagging strand synthesis in SPP1 origin-dependent DNA replication. Nucleic Acids Res 2017; 45:8302-8313. [PMID: 28575448 PMCID: PMC5737612 DOI: 10.1093/nar/gkx493] [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: 12/21/2016] [Accepted: 05/23/2017] [Indexed: 01/08/2023] Open
Abstract
Firmicutes have two distinct replicative DNA polymerases, the PolC leading strand polymerase, and PolC and DnaE synthesizing the lagging strand. We have reconstituted in vitro Bacillus subtilis bacteriophage SPP1 θ-type DNA replication, which initiates unidirectionally at oriL. With this system we show that DnaE is not only restricted to lagging strand synthesis as previously suggested. DnaG primase and DnaE polymerase are required for initiation of DNA replication on both strands. DnaE and DnaG synthesize in concert a hybrid RNA/DNA ‘initiation primer’ on both leading and lagging strands at the SPP1 oriL region, as it does the eukaryotic Pol α complex. DnaE, as a RNA-primed DNA polymerase, extends this initial primer in a reaction modulated by DnaG and one single-strand binding protein (SSB, SsbA or G36P), and hands off the initiation primer to PolC, a DNA-primed DNA polymerase. Then, PolC, stimulated by DnaG and the SSBs, performs the bulk of DNA chain elongation at both leading and lagging strands. Overall, these modulations by the SSBs and DnaG may contribute to the mechanism of polymerase switch at Firmicutes replisomes.
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Affiliation(s)
- Elena M Seco
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - Silvia Ayora
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
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24
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RNA primer-primase complexes serve as the signal for polymerase recycling and Okazaki fragment initiation in T4 phage DNA replication. Proc Natl Acad Sci U S A 2017; 114:5635-5640. [PMID: 28507156 DOI: 10.1073/pnas.1620459114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The opposite strand polarity of duplex DNA necessitates that the leading strand is replicated continuously whereas the lagging strand is replicated in discrete segments known as Okazaki fragments. The lagging-strand polymerase sometimes recycles to begin the synthesis of a new Okazaki fragment before finishing the previous fragment, creating a gap between the Okazaki fragments. The mechanism and signal that initiate this behavior-that is, the signaling mechanism-have not been definitively identified. We examined the role of RNA primer-primase complexes left on the lagging ssDNA from primer synthesis in initiating early lagging-strand polymerase recycling. We show for the T4 bacteriophage DNA replication system that primer-primase complexes have a residence time similar to the timescale of Okazaki fragment synthesis and the ability to block a holoenzyme synthesizing DNA and stimulate the dissociation of the holoenzyme to trigger polymerase recycling. The collision with primer-primase complexes triggering the early termination of Okazaki fragment synthesis has distinct advantages over those previously proposed because this signal requires no transmission to the lagging-strand polymerase through protein or DNA interactions, the mechanism for rapid dissociation of the holoenzyme is always collision, and no unique characteristics need to be assigned to either identical polymerase in the replisome. We have modeled repeated cycles of Okazaki fragment initiation using a collision with a completed Okazaki fragment or primer-primase complexes as the recycling mechanism. The results reproduce experimental data, providing insights into events related to Okazaki fragment initiation and the overall functioning of DNA replisomes.
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25
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Duderstadt KE, Geertsema HJ, Stratmann SA, Punter CM, Kulczyk AW, Richardson CC, van Oijen AM. Simultaneous Real-Time Imaging of Leading and Lagging Strand Synthesis Reveals the Coordination Dynamics of Single Replisomes. Mol Cell 2016; 64:1035-1047. [PMID: 27889453 DOI: 10.1016/j.molcel.2016.10.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/18/2016] [Accepted: 10/20/2016] [Indexed: 11/16/2022]
Abstract
The molecular machinery responsible for DNA replication, the replisome, must efficiently coordinate DNA unwinding with priming and synthesis to complete duplication of both strands. Due to the anti-parallel nature of DNA, the leading strand is copied continuously, while the lagging strand is produced by repeated cycles of priming, DNA looping, and Okazaki-fragment synthesis. Here, we report a multidimensional single-molecule approach to visualize this coordination in the bacteriophage T7 replisome by simultaneously monitoring the kinetics of loop growth and leading-strand synthesis. We show that loops in the lagging strand predominantly occur during priming and only infrequently support subsequent Okazaki-fragment synthesis. Fluorescence imaging reveals polymerases remaining bound to the lagging strand behind the replication fork, consistent with Okazaki-fragment synthesis behind and independent of the replication complex. Individual replisomes display both looping and pausing during priming, reconciling divergent models for the regulation of primer synthesis and revealing an underlying plasticity in replisome operation.
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Affiliation(s)
- Karl E Duderstadt
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands; Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Physik Department, Technische Universität München, 85748 Garching, Germany.
| | - Hylkje J Geertsema
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands
| | - Sarah A Stratmann
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands
| | - Christiaan M Punter
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands
| | - Arkadiusz W Kulczyk
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Charles C Richardson
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Antoine M van Oijen
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands; Centre for Medical and Molecular Bioscience, Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
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26
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Wegrzyn KE, Gross M, Uciechowska U, Konieczny I. Replisome Assembly at Bacterial Chromosomes and Iteron Plasmids. Front Mol Biosci 2016; 3:39. [PMID: 27563644 PMCID: PMC4980987 DOI: 10.3389/fmolb.2016.00039] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/25/2016] [Indexed: 11/13/2022] Open
Abstract
The proper initiation and occurrence of DNA synthesis depends on the formation and rearrangements of nucleoprotein complexes within the origin of DNA replication. In this review article, we present the current knowledge on the molecular mechanism of replication complex assembly at the origin of bacterial chromosome and plasmid replicon containing direct repeats (iterons) within the origin sequence. We describe recent findings on chromosomal and plasmid replication initiators, DnaA and Rep proteins, respectively, and their sequence-specific interactions with double- and single-stranded DNA. Also, we discuss the current understanding of the activities of DnaA and Rep proteins required for replisome assembly that is fundamental to the duplication and stability of genetic information in bacterial cells.
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Affiliation(s)
- Katarzyna E Wegrzyn
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Marta Gross
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Urszula Uciechowska
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
| | - Igor Konieczny
- Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk Gdansk, Poland
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27
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Chen R, Subramanyam S, Elcock AH, Spies M, Wold MS. Dynamic binding of replication protein a is required for DNA repair. Nucleic Acids Res 2016; 44:5758-72. [PMID: 27131385 PMCID: PMC4937323 DOI: 10.1093/nar/gkw339] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 04/15/2016] [Indexed: 12/14/2022] Open
Abstract
Replication protein A (RPA), the major eukaryotic single-stranded DNA (ssDNA) binding protein, is essential for replication, repair and recombination. High-affinity ssDNA-binding by RPA depends on two DNA binding domains in the large subunit of RPA. Mutation of the evolutionarily conserved aromatic residues in these two domains results in a separation-of-function phenotype: aromatic residue mutants support DNA replication but are defective in DNA repair. We used biochemical and single-molecule analyses, and Brownian Dynamics simulations to determine the molecular basis of this phenotype. Our studies demonstrated that RPA binds to ssDNA in at least two modes characterized by different dissociation kinetics. We also showed that the aromatic residues contribute to the formation of the longer-lived state, are required for stable binding to short ssDNA regions and are needed for RPA melting of partially duplex DNA structures. We conclude that stable binding and/or the melting of secondary DNA structures by RPA is required for DNA repair, including RAD51 mediated DNA strand exchange, but is dispensable for DNA replication. It is likely that the binding modes are in equilibrium and reflect dynamics in the RPA-DNA complex. This suggests that dynamic binding of RPA to DNA is necessary for different cellular functions.
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Affiliation(s)
- Ran Chen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Shyamal Subramanyam
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Adrian H Elcock
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Marc S Wold
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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28
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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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29
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Brown LT, Sutera VA, Zhou S, Weitzel CS, Cheng Y, Lovett ST. Connecting Replication and Repair: YoaA, a Helicase-Related Protein, Promotes Azidothymidine Tolerance through Association with Chi, an Accessory Clamp Loader Protein. PLoS Genet 2015; 11:e1005651. [PMID: 26544712 PMCID: PMC4636137 DOI: 10.1371/journal.pgen.1005651] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 10/14/2015] [Indexed: 11/23/2022] Open
Abstract
Elongating DNA polymerases frequently encounter lesions or structures that impede progress and require repair before DNA replication can be completed. Therefore, directing repair factors to a blocked fork, without interfering with normal replication, is important for proper cell function, and it is a process that is not well understood. To study this process, we have employed the chain-terminating nucleoside analog, 3’ azidothymidine (AZT) and the E. coli genetic system, for which replication and repair factors have been well-defined. By using high-expression suppressor screens, we identified yoaA, encoding a putative helicase, and holC, encoding the Chi component of the replication clamp loader, as genes that promoted tolerance to AZT. YoaA is a putative Fe-S helicase in the XPD/RAD3 family for which orthologs can be found in most bacterial genomes; E. coli has a paralog to YoaA, DinG, which possesses 5’ to 3’ helicase activity and an Fe-S cluster essential to its activity. Mutants in yoaA are sensitive to AZT exposure; dinG mutations cause mild sensitivity to AZT and exacerbate the sensitivity of yoaA mutant strains. Suppression of AZT sensitivity by holC or yoaA was mutually codependent and we provide evidence here that YoaA and Chi physically interact. Interactions of Chi with single-strand DNA binding protein (SSB) and with Psi were required to aid AZT tolerance, as was the proofreading 3’ exonuclease, DnaQ. Our studies suggest that repair is coupled to blocked replication through these interactions. We hypothesize that SSB, through Chi, recruits the YoaA helicase to replication gaps and that unwinding of the nascent strand promotes repair and AZT excision. This recruitment prevents the toxicity of helicase activity and aids the handoff of repair with replication factors, ensuring timely repair and resumption of replication. During the replication of the cell’s genetic material, difficulties are often encountered. These problems require the recruitment of special proteins to repair DNA so that replication can be completed. The failure to do so causes cell death or deleterious changes to the cell’s genetic material. In humans, these genetic changes can promote cancer formation. Our study identifies a repair protein that is recruited to problem sites by interactions with the replication machinery. These interactions provide a means by which the cell can sense, respond to and repair damage that interferes with the completion of DNA replication.
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Affiliation(s)
- Laura T. Brown
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, Massachusetts, United States of America
| | - Vincent A. Sutera
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, Massachusetts, United States of America
| | - Shen Zhou
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, Massachusetts, United States of America
| | - Christopher S. Weitzel
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, Massachusetts, United States of America
| | - Yisha Cheng
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, Massachusetts, United States of America
| | - Susan T. Lovett
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, Massachusetts, United States of America
- * E-mail:
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30
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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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31
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Chodavarapu S, Jones AD, Feig M, Kaguni JM. DnaC traps DnaB as an open ring and remodels the domain that binds primase. Nucleic Acids Res 2015; 44:210-20. [PMID: 26420830 PMCID: PMC4705694 DOI: 10.1093/nar/gkv961] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/11/2015] [Indexed: 11/23/2022] Open
Abstract
Helicase loading at a DNA replication origin often requires the dynamic interactions between the DNA helicase and an accessory protein. In E. coli, the DNA helicase is DnaB and DnaC is its loading partner. We used the method of hydrogen/deuterium exchange mass spectrometry to address the importance of DnaB–DnaC complex formation as a prerequisite for helicase loading. Our results show that the DnaB ring opens and closes, and that specific amino acids near the N-terminus of DnaC interact with a site in DnaB's C-terminal domain to trap it as an open ring. This event correlates with conformational changes of the RecA fold of DnaB that is involved in nucleotide binding, and of the AAA+ domain of DnaC. DnaC also causes an alteration of the helical hairpins in the N-terminal domain of DnaB, presumably occluding this region from interacting with primase. Hence, DnaC controls the access of DnaB by primase.
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Affiliation(s)
- Sundari Chodavarapu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA
| | - A Daniel Jones
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA Department of Chemistry, Michigan State University, East Lansing, MI 48824-1319, USA
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA Department of Chemistry, Michigan State University, East Lansing, MI 48824-1319, USA
| | - Jon M Kaguni
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1319, USA
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32
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Plasmid replication initiator interactions with origin 13-mers and polymerase subunits contribute to strand-specific replisome assembly. Proc Natl Acad Sci U S A 2015. [PMID: 26195759 DOI: 10.1073/pnas.1504926112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although the molecular basis for replisome activity has been extensively investigated, it is not clear what the exact mechanism for de novo assembly of the replication complex at the replication origin is, or how the directionality of replication is determined. Here, using the plasmid RK2 replicon, we analyze the protein interactions required for Escherichia coli polymerase III (Pol III) holoenzyme association at the replication origin. Our investigations revealed that in E. coli, replisome formation at the plasmid origin involves interactions of the RK2 plasmid replication initiation protein (TrfA) with both the polymerase β- and α-subunits. In the presence of other replication proteins, including DnaA, helicase, primase and the clamp loader, TrfA interaction with the β-clamp contributes to the formation of the β-clamp nucleoprotein complex on origin DNA. By reconstituting in vitro the replication reaction on ssDNA templates, we demonstrate that TrfA interaction with the β-clamp and sequence-specific TrfA interaction with one strand of the plasmid origin DNA unwinding element (DUE) contribute to strand-specific replisome assembly. Wild-type TrfA, but not the TrfA QLSLF mutant (which does not interact with the β-clamp), in the presence of primase, helicase, Pol III core, clamp loader, and β-clamp initiates DNA synthesis on ssDNA template containing 13-mers of the bottom strand, but not the top strand, of DUE. Results presented in this work uncovered requirements for anchoring polymerase at the plasmid replication origin and bring insights of how the directionality of DNA replication is determined.
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Abstract
DNA replication is essential for all life forms. Although the process is fundamentally conserved in the three domains of life, bioinformatic, biochemical, structural, and genetic studies have demonstrated that the process and the proteins involved in archaeal DNA replication are more similar to those in eukaryal DNA replication than in bacterial DNA replication, but have some archaeal-specific features. The archaeal replication system, however, is not monolithic, and there are some differences in the replication process between different species. In this review, the current knowledge of the mechanisms governing DNA replication in Archaea is summarized. The general features of the replication process as well as some of the differences are discussed.
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Affiliation(s)
- Lori M Kelman
- Program in Biotechnology, Montgomery College, Germantown, Maryland 20876;
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34
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Beattie TR, Reyes-Lamothe R. A Replisome's journey through the bacterial chromosome. Front Microbiol 2015; 6:562. [PMID: 26097470 PMCID: PMC4456610 DOI: 10.3389/fmicb.2015.00562] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 05/21/2015] [Indexed: 01/03/2023] Open
Abstract
Genome duplication requires the coordinated activity of a multi-component machine, the replisome. In contrast to the background of metabolic diversity across the bacterial domain, the composition and architecture of the bacterial replisome seem to have suffered few changes during evolution. This immutability underlines the replisome’s efficiency in copying the genome. It also highlights the success of various strategies inherent to the replisome for responding to stress and avoiding problems during critical stages of DNA synthesis. Here we summarize current understanding of bacterial replisome architecture and highlight the known variations in different bacterial taxa. We then look at the mechanisms in place to ensure that the bacterial replisome is assembled appropriately on DNA, kept together during elongation, and disassembled upon termination. We put forward the idea that the architecture of the replisome may be more flexible that previously thought and speculate on elements of the replisome that maintain its stability to ensure a safe journey from origin to terminus.
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35
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Petzold C, Marceau AH, Miller KH, Marqusee S, Keck JL. Interaction with Single-stranded DNA-binding Protein Stimulates Escherichia coli Ribonuclease HI Enzymatic Activity. J Biol Chem 2015; 290:14626-36. [PMID: 25903123 PMCID: PMC4505529 DOI: 10.1074/jbc.m115.655134] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 04/16/2015] [Indexed: 12/21/2022] Open
Abstract
Single-stranded (ss) DNA-binding proteins (SSBs) bind and protect ssDNA intermediates formed during replication, recombination, and repair reactions. SSBs also directly interact with many different genome maintenance proteins to stimulate their enzymatic activities and/or mediate their proper cellular localization. We have identified an interaction formed between Escherichia coli SSB and ribonuclease HI (RNase HI), an enzyme that hydrolyzes RNA in RNA/DNA hybrids. The RNase HI·SSB complex forms by RNase HI binding the intrinsically disordered C terminus of SSB (SSB-Ct), a mode of interaction that is shared among all SSB interaction partners examined to date. Residues that comprise the SSB-Ct binding site are conserved among bacterial RNase HI enzymes, suggesting that RNase HI·SSB complexes are present in many bacterial species and that retaining the interaction is important for its cellular function. A steady-state kinetic analysis shows that interaction with SSB stimulates RNase HI activity by lowering the reaction Km. SSB or RNase HI protein variants that disrupt complex formation nullify this effect. Collectively our findings identify a direct RNase HI/SSB interaction that could play a role in targeting RNase HI activity to RNA/DNA hybrid substrates within the genome.
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Affiliation(s)
- Christine Petzold
- From the Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Aimee H Marceau
- From the Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Katherine H Miller
- California Institute for Quantitative Biosciences, QB3 and Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Susan Marqusee
- California Institute for Quantitative Biosciences, QB3 and Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - James L Keck
- From the Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
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36
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Sugitani N, Chazin WJ. Characteristics and concepts of dynamic hub proteins in DNA processing machinery from studies of RPA. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 117:206-211. [PMID: 25542993 DOI: 10.1016/j.pbiomolbio.2014.12.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 12/15/2014] [Accepted: 12/16/2014] [Indexed: 11/26/2022]
Abstract
DNA replication, damage response and repair require the coordinated action of multi-domain proteins operating within dynamic multi-protein machines that act upon the DNA substrate. These modular proteins contain flexible linkers of various lengths, which enable changes in the spatial distribution of the globular domains (architecture) that harbor their essential biochemical functions. This mobile architecture is uniquely suited to follow the evolving substrate landscape present over the course of the specific process performed by the multi-protein machinery. A fundamental advance in understanding of protein machinery is the realization of the pervasive role of dynamics. Not only is the machine undergoing dynamic transformations, but the proteins themselves are flexible and constantly adapting to the progression through the steps of the overall process. Within this dynamic context the activity of the constituent proteins must be coordinated, a role typically played by hub proteins. A number of important characteristics of modular proteins and concepts about the operation of dynamic machinery have been discerned. These provide the underlying basis for the action of the machinery that reads DNA, and responds to and repairs DNA damage. Here, we introduce a number of key characteristics and concepts, including the modularity of the proteins, linkage of weak binding sites, direct competition between sites, and allostery, using the well recognized hub protein replication protein A (RPA).
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Affiliation(s)
- Norie Sugitani
- Center for Structural Biology and Departments of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Walter J Chazin
- Center for Structural Biology and Departments of Biochemistry and Chemistry, Vanderbilt University, Nashville, TN, USA.
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37
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Green M, Gilhooly NS, Abedeen S, Scott DJ, Dillingham MS, Soultanas P. Engineering a reagentless biosensor for single-stranded DNA to measure real-time helicase activity in Bacillus. Biosens Bioelectron 2014; 61:579-86. [PMID: 24953846 PMCID: PMC4103019 DOI: 10.1016/j.bios.2014.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/28/2014] [Accepted: 06/03/2014] [Indexed: 10/27/2022]
Abstract
Single-stranded DNA-binding protein (SSB) is a well characterized ubiquitous and essential bacterial protein involved in almost all aspects of DNA metabolism. Using the Bacillus subtilis SSB we have generated a reagentless SSB biosensor that can be used as a helicase probe in B. subtilis and closely related gram positive bacteria. We have demonstrated the utility of the probe in a DNA unwinding reaction using a helicase from Bacillus and for the first time, characterized the B. subtilis SSB's DNA binding mode switching and stoichiometry. The importance of SSB in DNA metabolism is not limited to simply binding and protecting ssDNA during DNA replication, as previously thought. It interacts with an array of partner proteins to coordinate many different aspects of DNA metabolism. In most cases its interactions with partner proteins is species-specific and for this reason, knowing how to produce and use cognate reagentless SSB biosensors in different bacteria is critical. Here we explain how to produce a B. subtilis SSB probe that exhibits 9-fold fluorescence increase upon binding to single stranded DNA and can be used in all related gram positive firmicutes which employ drastically different DNA replication and repair systems than the widely studied Escherichia coli. The materials to produce the B. subtilis SSB probe are commercially available, so the methodology described here is widely available unlike previously published methods for the E. coli SSB.
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Affiliation(s)
- Matthew Green
- School of Chemistry, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Neville S Gilhooly
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Shahriar Abedeen
- School of Chemistry, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - David J Scott
- School of Biosciences, University of Nottingham, Sutton Bonington, Leicestershire LE12 5RD, UK
| | - Mark S Dillingham
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Panos Soultanas
- School of Chemistry, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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38
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ssb gene duplication restores the viability of ΔholC and ΔholD Escherichia coli mutants. PLoS Genet 2014; 10:e1004719. [PMID: 25329071 PMCID: PMC4199511 DOI: 10.1371/journal.pgen.1004719] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 08/29/2014] [Indexed: 11/20/2022] Open
Abstract
The HolC-HolD (χψ) complex is part of the DNA polymerase III holoenzyme (Pol III HE) clamp-loader. Several lines of evidence indicate that both leading- and lagging-strand synthesis are affected in the absence of this complex. The Escherichia coli ΔholD mutant grows poorly and suppressor mutations that restore growth appear spontaneously. Here we show that duplication of the ssb gene, encoding the single-stranded DNA binding protein (SSB), restores ΔholD mutant growth at all temperatures on both minimal and rich medium. RecFOR-dependent SOS induction, previously shown to occur in the ΔholD mutant, is unaffected by ssb gene duplication, suggesting that lagging-strand synthesis remains perturbed. The C-terminal SSB disordered tail, which interacts with several E. coli repair, recombination and replication proteins, must be intact in both copies of the gene in order to restore normal growth. This suggests that SSB-mediated ΔholD suppression involves interaction with one or more partner proteins. ssb gene duplication also suppresses ΔholC single mutant and ΔholC ΔholD double mutant growth defects, indicating that it bypasses the need for the entire χψ complex. We propose that doubling the amount of SSB stabilizes HolCD-less Pol III HE DNA binding through interactions between SSB and a replisome component, possibly DnaE. Given that SSB binds DNA in vitro via different binding modes depending on experimental conditions, including SSB protein concentration and SSB interactions with partner proteins, our results support the idea that controlling the balance between SSB binding modes is critical for DNA Pol III HE stability in vivo, with important implications for DNA replication and genome stability.
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Nonstructural protein 5A (NS5A) and human replication protein A increase the processivity of hepatitis C virus NS5B polymerase activity in vitro. J Virol 2014; 89:165-80. [PMID: 25320291 DOI: 10.1128/jvi.01677-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
UNLABELLED The precise role(s) and topological organization of different factors in the hepatitis C virus (HCV) RNA replication complex are not well understood. In order to elucidate the role of viral and host proteins in HCV replication, we have developed a novel in vitro replication system that utilizes a rolling-circle RNA template. Under close-to-physiological salt conditions, HCV NS5BΔ21, an RNA-dependent RNA polymerase, has poor affinity for the RNA template. Human replication protein A (RPA) and HCV NS5A recruit NS5BΔ21 to the template. Subsequently, NS3 is recruited to the replication complex by NS5BΔ21, resulting in RNA synthesis stimulation by helicase. Both RPA and NS5A(S25-C447), but not NS5A(S25-K215), enabled the NS5BΔ21-NS3 helicase complex to be stably associated with the template and synthesize RNA product in a highly processive manner in vitro. This new in vitro HCV replication system is a useful tool that may facilitate the study of other replication factors and aid in the discovery of novel inhibitors of HCV replication. IMPORTANCE The molecular mechanism of hepatitis C virus (HCV) replication is not fully understood, but viral and host proteins collaborate in this process. Using a rolling-circle RNA template, we have reconstituted an in vitro HCV replication system that allows us to interrogate the role of viral and host proteins in HCV replication and delineate the molecular interactions. We showed that HCV NS5A(S25-C447) and cellular replication protein A (RPA) functionally cooperate as a processivity factor to stimulate HCV replication by HCV NS5BΔ21 polymerase and NS3 helicase. This system paves the way to test other proteins and may be used as an assay for discovery of HCV inhibitors.
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40
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Hayner JN, Douma LG, Bloom LB. The interplay of primer-template DNA phosphorylation status and single-stranded DNA binding proteins in directing clamp loaders to the appropriate polarity of DNA. Nucleic Acids Res 2014; 42:10655-67. [PMID: 25159615 PMCID: PMC4176372 DOI: 10.1093/nar/gku774] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Sliding clamps are loaded onto DNA by clamp loaders to serve the critical role of coordinating various enzymes on DNA. Clamp loaders must quickly and efficiently load clamps at primer/template (p/t) junctions containing a duplex region with a free 3′OH (3′DNA), but it is unclear how clamp loaders target these sites. To measure the Escherichia coli and Saccharomyces cerevisiae clamp loader specificity toward 3′DNA, fluorescent β and PCNA clamps were used to measure clamp closing triggered by DNA substrates of differing polarity, testing the role of both the 5′phosphate (5′P) and the presence of single-stranded binding proteins (SSBs). SSBs inhibit clamp loading by both clamp loaders on the incorrect polarity of DNA (5′DNA). The 5′P groups contribute selectivity to differing degrees for the two clamp loaders, suggesting variations in the mechanism by which clamp loaders target 3′DNA. Interestingly, the χ subunit of the E. coli clamp loader is not required for SSB to inhibit clamp loading on phosphorylated 5′DNA, showing that χ·SSB interactions are dispensable. These studies highlight a common role for SSBs in directing clamp loaders to 3′DNA, as well as uncover nuances in the mechanisms by which SSBs perform this vital role.
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Affiliation(s)
- Jaclyn N Hayner
- Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Lauren G Douma
- Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Linda B Bloom
- Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
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41
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Curtis FA, Malay AD, Trotter AJ, Wilson LA, Barradell-Black MMH, Bowers LY, Reed P, Hillyar CRT, Yeo RP, Sanderson JM, Heddle JG, Sharples GJ. Phage ORF family recombinases: conservation of activities and involvement of the central channel in DNA binding. PLoS One 2014; 9:e102454. [PMID: 25083707 PMCID: PMC4118853 DOI: 10.1371/journal.pone.0102454] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/17/2014] [Indexed: 01/05/2023] Open
Abstract
Genetic and biochemical evidence suggests that λ Orf is a recombination mediator, promoting nucleation of either bacterial RecA or phage Redβ recombinases onto single-stranded DNA (ssDNA) bound by SSB protein. We have identified a diverse family of Orf proteins that includes representatives implicated in DNA base flipping and those fused to an HNH endonuclease domain. To confirm a functional relationship with the Orf family, a distantly-related homolog, YbcN, from Escherichia coli cryptic prophage DLP12 was purified and characterized. As with its λ relative, YbcN showed a preference for binding ssDNA over duplex. Neither Orf nor YbcN displayed a significant preference for duplex DNA containing mismatches or 1-3 nucleotide bulges. YbcN also bound E. coli SSB, although unlike Orf, it failed to associate with an SSB mutant lacking the flexible C-terminal tail involved in coordinating heterologous protein-protein interactions. Residues conserved in the Orf family that flank the central cavity in the λ Orf crystal structure were targeted for mutagenesis to help determine the mode of DNA binding. Several of these mutant proteins showed significant defects in DNA binding consistent with the central aperture being important for substrate recognition. The widespread conservation of Orf-like proteins highlights the importance of targeting SSB coated ssDNA during lambdoid phage recombination.
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Affiliation(s)
- Fiona A. Curtis
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Ali D. Malay
- Heddle Initiative Research Unit, RIKEN, Wako, Saitama, Japan
| | - Alexander J. Trotter
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Lindsay A. Wilson
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Michael M. H. Barradell-Black
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Laura Y. Bowers
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Patricia Reed
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Christopher R. T. Hillyar
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - Robert P. Yeo
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | - John M. Sanderson
- Department of Chemistry, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
| | | | - Gary J. Sharples
- School of Biological and Biomedical Sciences, Biophysical Sciences Institute, Durham University, Durham, United Kingdom
- * E-mail:
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42
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Duderstadt KE, Reyes-Lamothe R, van Oijen AM, Sherratt DJ. Replication-fork dynamics. Cold Spring Harb Perspect Biol 2014; 6:cshperspect.a010157. [PMID: 23881939 DOI: 10.1101/cshperspect.a010157] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The proliferation of all organisms depends on the coordination of enzymatic events within large multiprotein replisomes that duplicate chromosomes. Whereas the structure and function of many core replisome components have been clarified, the timing and order of molecular events during replication remains obscure. To better understand the replication mechanism, new methods must be developed that allow for the observation and characterization of short-lived states and dynamic events at single replication forks. Over the last decade, great progress has been made toward this goal with the development of novel DNA nanomanipulation and fluorescence imaging techniques allowing for the direct observation of replication-fork dynamics both reconstituted in vitro and in live cells. This article reviews these new single-molecule approaches and the revised understanding of replisome operation that has emerged.
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Affiliation(s)
- Karl E Duderstadt
- Zernike Institute for Advanced Materials, University of Groningen, 9747 AG, Groningen, Netherlands
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43
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Multiple C-terminal tails within a single E. coli SSB homotetramer coordinate DNA replication and repair. J Mol Biol 2013; 425:4802-19. [PMID: 24021816 DOI: 10.1016/j.jmb.2013.08.021] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 08/01/2013] [Accepted: 08/16/2013] [Indexed: 11/21/2022]
Abstract
Escherichia coli single-stranded DNA binding protein (SSB) plays essential roles in DNA replication, recombination and repair. SSB functions as a homotetramer with each subunit possessing a DNA binding domain (OB-fold) and an intrinsically disordered C-terminus, of which the last nine amino acids provide the site for interaction with at least a dozen other proteins that function in DNA metabolism. To examine how many C-termini are needed for SSB function, we engineered covalently linked forms of SSB that possess only one or two C-termini within a four-OB-fold "tetramer". Whereas E. coli expressing SSB with only two tails can survive, expression of a single-tailed SSB is dominant lethal. E. coli expressing only the two-tailed SSB recovers faster from exposure to DNA damaging agents but accumulates more mutations. A single-tailed SSB shows defects in coupled leading and lagging strand DNA replication and does not support replication restart in vitro. These deficiencies in vitro provide a plausible explanation for the lethality observed in vivo. These results indicate that a single SSB tetramer must interact simultaneously with multiple protein partners during some essential roles in genome maintenance.
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44
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Kjelstrup S, Hansen PMP, Thomsen LE, Hansen PR, Løbner-Olesen A. Cyclic peptide inhibitors of the β-sliding clamp in Staphylococcus aureus. PLoS One 2013; 8:e72273. [PMID: 24023733 PMCID: PMC3762901 DOI: 10.1371/journal.pone.0072273] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 07/12/2013] [Indexed: 12/01/2022] Open
Abstract
Interaction between pairs of Staphylococcus aureus replication proteins was detected in an Escherichia coli based two-hybrid analysis. A reverse two-hybrid system was constructed for selection of compounds that hindered interaction between interacting protein pairs. A number of cyclic peptides, from a library generated by the split intein-mediated circular ligation of peptides and proteins technology, were found to interfere with dimerization of the β-sliding clamp of the replisome. Two 8-mer peptides were analyzed in more detail. Both inhibited DNA replication, led to SOS induction, altered cell morphology and cell death. The peptides were active when added to bacterial cultures indicating that they could traverse the bacterial membrane to find their intracellular target. Peptide specificity was confirmed by overproduction of the putative target (DnaN) which resulted in resistance. The minimum inhibitory concentration was ∼50 μg/ml for S. aureus cells. These compounds may serve as lead candidates for future development into novel classes of antibiotics as well as provide information on the function of the S. aureus replication process.
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Affiliation(s)
- Susanne Kjelstrup
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Line E. Thomsen
- Department of Veterinary Disease Biology, University of Copenhagen, Copenhagen, Denmark
| | - Paul Robert Hansen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Lopez-Vernaza MA, Leach DRF. WITHDRAWN: Symmetries and Asymmetries Associated with Non-Random Segregation of Sister DNA Strands in Escherichia coli. Semin Cell Dev Biol 2013:S1084-9521(13)00077-3. [PMID: 23692810 DOI: 10.1016/j.semcdb.2013.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 05/06/2013] [Indexed: 11/19/2022]
Abstract
The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.semcdb.2013.05.010. The duplicate article has therefore been withdrawn.
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Affiliation(s)
- Manuel A Lopez-Vernaza
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JR, United Kingdom
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46
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Lopez-Vernaza MA, Leach DRF. Symmetries and asymmetries associated with non-random segregation of sister DNA strands in Escherichia coli. Semin Cell Dev Biol 2013; 24:610-7. [PMID: 23685127 DOI: 10.1016/j.semcdb.2013.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The successful inheritance of genetic information across generations is a complex process requiring replication of the genome and its faithful segregation into two daughter cells. At each replication cycle there is a risk that new DNA strands incorporate genetic changes caused by miscopying of parental information. By contrast the parental strands retain the original information. This raises the intriguing possibility that specific cell lineages might inherit "immortal" parental DNA strands via non-random segregation. If so, this requires an understanding of the mechanisms of non-random segregation. Here, we review several aspects of asymmetry in the very symmetrical cell, Escherichia coli, in the interest of exploring the potential basis for non-random segregation of leading- and lagging-strand replicated chromosome arms. These considerations lead us to propose a model for DNA replication that integrates chromosome segregation and genomic localisation with non-random strand segregation.
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Affiliation(s)
- Manuel A Lopez-Vernaza
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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47
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Integrative modelling coupled with ion mobility mass spectrometry reveals structural features of the clamp loader in complex with single-stranded DNA binding protein. J Mol Biol 2013; 425:4790-801. [PMID: 23583780 DOI: 10.1016/j.jmb.2013.04.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/14/2013] [Accepted: 04/03/2013] [Indexed: 01/26/2023]
Abstract
DNA polymerase III, a decameric 420-kDa assembly, simultaneously replicates both strands of the chromosome in Escherichia coli. A subassembly of this holoenzyme, the seven-subunit clamp loader complex, is responsible for loading the sliding clamp (β2) onto DNA. Here, we use structural information derived from ion mobility mass spectrometry (IM-MS) to build three-dimensional models of one form of the full clamp loader complex, γ3δδ'ψχ (254 kDa). By probing the interaction between the clamp loader and a single-stranded DNA (ssDNA) binding protein (SSB4) and by identifying two distinct conformational states, with and without ssDNA, we assemble models of ψχ-SSB4 (108 kDa) and the clamp loader-SSB4 (340 kDa) consistent with IM data. A significant increase in measured collision cross-section (~10%) of the clamp loader-SSB4 complex upon DNA binding suggests large conformational rearrangements. This DNA bound conformation represents the active state and, along with the presence of ψχ, stabilises the clamp loader-SSB4 complex. Overall, this study of a large heteromeric complex analysed by IM-MS, coupled with integrative modelling, highlights the potential of such an approach to reveal structural features of previously unknown complexes of high biological importance.
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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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Marceau AH, Bernstein DA, Walsh BW, Shapiro W, Simmons LA, Keck JL. Protein interactions in genome maintenance as novel antibacterial targets. PLoS One 2013; 8:e58765. [PMID: 23536821 PMCID: PMC3594151 DOI: 10.1371/journal.pone.0058765] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/06/2013] [Indexed: 11/19/2022] Open
Abstract
Antibacterial compounds typically act by directly inhibiting essential bacterial enzyme activities. Although this general mechanism of action has fueled traditional antibiotic discovery efforts for decades, new antibiotic development has not kept pace with the emergence of drug resistant bacterial strains. These limitations have severely restricted the therapeutic tools available for treating bacterial infections. Here we test an alternative antibacterial lead-compound identification strategy in which essential protein-protein interactions are targeted rather than enzymatic activities. Bacterial single-stranded DNA-binding proteins (SSBs) form conserved protein interaction “hubs” that are essential for recruiting many DNA replication, recombination, and repair proteins to SSB/DNA nucleoprotein substrates. Three small molecules that block SSB/protein interactions are shown to have antibacterial activity against diverse bacterial species. Consistent with a model in which the compounds target multiple SSB/protein interactions, treatment of Bacillus subtilis cultures with the compounds leads to rapid inhibition of DNA replication and recombination, and ultimately to cell death. The compounds also have unanticipated effects on protein synthesis that could be due to a previously unknown role for SSB/protein interactions in translation or to off-target effects. Our results highlight the potential of targeting protein-protein interactions, particularly those that mediate genome maintenance, as a powerful approach for identifying new antibacterial compounds.
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Affiliation(s)
- Aimee H. Marceau
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Douglas A. Bernstein
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Brian W. Walsh
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Walker Shapiro
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - James L. Keck
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- * E-mail:
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50
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Naue N, Beerbaum M, Bogutzki A, Schmieder P, Curth U. The helicase-binding domain of Escherichia coli DnaG primase interacts with the highly conserved C-terminal region of single-stranded DNA-binding protein. Nucleic Acids Res 2013; 41:4507-17. [PMID: 23430154 PMCID: PMC3632105 DOI: 10.1093/nar/gkt107] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
During bacterial DNA replication, DnaG primase and the χ subunit of DNA polymerase III compete for binding to single-stranded DNA-binding protein (SSB), thus facilitating the switch between priming and elongation. SSB proteins play an essential role in DNA metabolism by protecting single-stranded DNA and by mediating several important protein-protein interactions. Although an interaction of SSB with primase has been previously reported, it was unclear which domains of the two proteins are involved. This study identifies the C-terminal helicase-binding domain of DnaG primase (DnaG-C) and the highly conserved C-terminal region of SSB as interaction sites. By ConSurf analysis, it can be shown that an array of conserved amino acids on DnaG-C forms a hydrophobic pocket surrounded by basic residues, reminiscent of known SSB-binding sites on other proteins. Using protein-protein cross-linking, site-directed mutagenesis, analytical ultracentrifugation and nuclear magnetic resonance spectroscopy, we demonstrate that these conserved amino acid residues are involved in the interaction with SSB. Even though the C-terminal domain of DnaG primase also participates in the interaction with DnaB helicase, the respective binding sites on the surface of DnaG-C do not overlap, as SSB binds to the N-terminal subdomain, whereas DnaB interacts with the ultimate C-terminus.
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Affiliation(s)
- Natalie Naue
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
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