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Maslowska KH, Makiela‐Dzbenska K, Fijalkowska IJ. The SOS system: A complex and tightly regulated response to DNA damage. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:368-384. [PMID: 30447030 PMCID: PMC6590174 DOI: 10.1002/em.22267] [Citation(s) in RCA: 221] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/29/2018] [Accepted: 11/13/2018] [Indexed: 05/10/2023]
Abstract
Genomes of all living organisms are constantly threatened by endogenous and exogenous agents that challenge the chemical integrity of DNA. Most bacteria have evolved a coordinated response to DNA damage. In Escherichia coli, this inducible system is termed the SOS response. The SOS global regulatory network consists of multiple factors promoting the integrity of DNA as well as error-prone factors allowing for survival and continuous replication upon extensive DNA damage at the cost of elevated mutagenesis. Due to its mutagenic potential, the SOS response is subject to elaborate regulatory control involving not only transcriptional derepression, but also post-translational activation, and inhibition. This review summarizes current knowledge about the molecular mechanism of the SOS response induction and progression and its consequences for genome stability. Environ. Mol. Mutagen. 60:368-384, 2019. © 2018 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
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Affiliation(s)
- Katarzyna H. Maslowska
- Cancer Research Center of Marseille, CNRS, UMR7258Inserm, U1068; Institut Paoli‐Calmettes, Aix‐Marseille UniversityMarseilleFrance
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
| | | | - Iwona J. Fijalkowska
- Institute of Biochemistry and Biophysics, Polish Academy of SciencesWarsawPoland
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2
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Abstract
The complex binding dynamics between DNA and proteins are often obscured by ensemble averaging effects in conventional biochemical experiments. Single-molecule fluorescence methods are powerful tools to investigate DNA-protein interaction dynamics in real time. In this chapter, we focus on using single-molecule Förster Resonance Energy Transfer (smFRET) to probe the binding dynamics of individual proteins on single DNA molecules. We provide a detailed discussion of total internal reflection fluorescence (TIRF) instrument design, nucleic acid labeling with fluorophores, flow cell surface passivation, and data analysis methods.
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Affiliation(s)
- Kathy R Chaurasiya
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands.
| | - Remus T Dame
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands
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Trakselis MA, Cranford MT, Chu AM. Coordination and Substitution of DNA Polymerases in Response to Genomic Obstacles. Chem Res Toxicol 2017; 30:1956-1971. [PMID: 28881136 DOI: 10.1021/acs.chemrestox.7b00190] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability for DNA polymerases (Pols) to overcome a variety of obstacles in its path to maintain genomic stability during replication is a complex endeavor. It requires the coordination of multiple Pols with differing specificities through molecular control and access to the replisome. Although a number of contacts directly between Pols and accessory proteins have been identified, forming the basis of a variety of holoenzyme complexes, the dynamics of Pol active site substitutions remain uncharacterized. Substitutions can occur externally by recruiting new Pols to replisome complexes through an "exchange" of enzyme binding or internally through a "switch" in the engagement of DNA from preformed associated enzymes contained within supraholoenzyme complexes. Models for how high fidelity (HiFi) replication Pols can be substituted by translesion synthesis (TLS) Pols at sites of damage during active replication will be discussed. These substitution mechanisms may be as diverse as the number of Pol families and types of damage; however, common themes can be recognized across species. Overall, Pol substitutions will be controlled by explicit protein contacts, complex multiequilibrium processes, and specific kinetic activities. Insight into how these dynamic processes take place and are regulated will be of utmost importance for our greater understanding of the specifics of TLS as well as providing for future novel chemotherapeutic and antimicrobial strategies.
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Affiliation(s)
- Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Matthew T Cranford
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Aurea M Chu
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
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Murison DA, Timson RC, Koleva BN, Ordazzo M, Beuning PJ. Identification of the Dimer Exchange Interface of the Bacterial DNA Damage Response Protein UmuD. Biochemistry 2017; 56:4773-4785. [DOI: 10.1021/acs.biochem.7b00560] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David A. Murison
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Rebecca C. Timson
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Bilyana N. Koleva
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Michael Ordazzo
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Penny J. Beuning
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
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Murison DA, Ollivierre JN, Huang Q, Budil DE, Beuning PJ. Altering the N-terminal arms of the polymerase manager protein UmuD modulates protein interactions. PLoS One 2017; 12:e0173388. [PMID: 28273172 PMCID: PMC5342242 DOI: 10.1371/journal.pone.0173388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 02/14/2017] [Indexed: 12/02/2022] Open
Abstract
Escherichia coli cells that are exposed to DNA damaging agents invoke the SOS response that involves expression of the umuD gene products, along with more than 50 other genes. Full-length UmuD is expressed as a 139-amino-acid protein, which eventually cleaves its N-terminal 24 amino acids to form UmuD'. The N-terminal arms of UmuD are dynamic and contain recognition sites for multiple partner proteins. Cleavage of UmuD to UmuD' dramatically affects the function of the protein and activates UmuC for translesion synthesis (TLS) by forming DNA Polymerase V. To probe the roles of the N-terminal arms in the cellular functions of the umuD gene products, we constructed additional N-terminal truncated versions of UmuD: UmuD 8 (UmuD Δ1-7) and UmuD 18 (UmuD Δ1-17). We found that the loss of just the N-terminal seven (7) amino acids of UmuD results in changes in conformation of the N-terminal arms, as determined by electron paramagnetic resonance spectroscopy with site-directed spin labeling. UmuD 8 is cleaved as efficiently as full-length UmuD in vitro and in vivo, but expression of a plasmid-borne non-cleavable variant of UmuD 8 causes hypersensitivity to UV irradiation, which we determined is the result of a copy-number effect. UmuD 18 does not cleave to form UmuD', but confers resistance to UV radiation. Moreover, removal of the N-terminal seven residues of UmuD maintained its interactions with the alpha polymerase subunit of DNA polymerase III as well as its ability to disrupt interactions between alpha and the beta processivity clamp, whereas deletion of the N-terminal 17 residues resulted in decreases in binding to alpha and in the ability to disrupt the alpha-beta interaction. We find that UmuD 8 mimics full-length UmuD in many respects, whereas UmuD 18 lacks a number of functions characteristic of UmuD.
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Affiliation(s)
- David A. Murison
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - Jaylene N. Ollivierre
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - Qiuying Huang
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - David E. Budil
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
| | - Penny J. Beuning
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, United States of America
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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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Gu S, Li W, Zhang H, Fleming J, Yang W, Wang S, Wei W, Zhou J, Zhu G, Deng J, Hou J, Zhou Y, Lin S, Zhang XE, Bi L. The β2 clamp in the Mycobacterium tuberculosis DNA polymerase III αβ2ε replicase promotes polymerization and reduces exonuclease activity. Sci Rep 2016; 6:18418. [PMID: 26822057 PMCID: PMC4731781 DOI: 10.1038/srep18418] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/17/2015] [Indexed: 12/20/2022] Open
Abstract
DNA polymerase III (DNA pol III) is a multi-subunit replication machine responsible for the accurate and rapid replication of bacterial genomes, however, how it functions in Mycobacterium tuberculosis (Mtb) requires further investigation. We have reconstituted the leading-strand replication process of the Mtb DNA pol III holoenzyme in vitro, and investigated the physical and functional relationships between its key components. We verify the presence of an αβ2ε polymerase-clamp-exonuclease replicase complex by biochemical methods and protein-protein interaction assays in vitro and in vivo and confirm that, in addition to the polymerase activity of its α subunit, Mtb DNA pol III has two potential proofreading subunits; the α and ε subunits. During DNA replication, the presence of the β2 clamp strongly promotes the polymerization of the αβ2ε replicase and reduces its exonuclease activity. Our work provides a foundation for further research on the mechanism by which the replication machinery switches between replication and proofreading and provides an experimental platform for the selection of antimicrobials targeting DNA replication in Mtb.
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Affiliation(s)
- Shoujin Gu
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjuan Li
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongtai Zhang
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Joy Fleming
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Weiqiang Yang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Shihua Wang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Wenjing Wei
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jie Zhou
- The Fourth People's Hospital, Foshan 528000, China
| | - Guofeng Zhu
- Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China
| | - Jiaoyu Deng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Jian Hou
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ying Zhou
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shiqiang Lin
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xian-En Zhang
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lijun Bi
- Key Laboratory of RNA Biology &National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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A Genetic Selection for dinB Mutants Reveals an Interaction between DNA Polymerase IV and the Replicative Polymerase That Is Required for Translesion Synthesis. PLoS Genet 2015; 11:e1005507. [PMID: 26352807 PMCID: PMC4564189 DOI: 10.1371/journal.pgen.1005507] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/14/2015] [Indexed: 11/19/2022] Open
Abstract
Translesion DNA synthesis (TLS) by specialized DNA polymerases (Pols) is a conserved mechanism for tolerating replication blocking DNA lesions. The actions of TLS Pols are managed in part by ring-shaped sliding clamp proteins. In addition to catalyzing TLS, altered expression of TLS Pols impedes cellular growth. The goal of this study was to define the relationship between the physiological function of Escherichia coli Pol IV in TLS and its ability to impede growth when overproduced. To this end, 13 novel Pol IV mutants were identified that failed to impede growth. Subsequent analysis of these mutants suggest that overproduced levels of Pol IV inhibit E. coli growth by gaining inappropriate access to the replication fork via a Pol III-Pol IV switch that is mechanistically similar to that used under physiological conditions to coordinate Pol IV-catalyzed TLS with Pol III-catalyzed replication. Detailed analysis of one mutant, Pol IV-T120P, and two previously described Pol IV mutants impaired for interaction with either the rim (Pol IVR) or the cleft (Pol IVC) of the β sliding clamp revealed novel insights into the mechanism of the Pol III-Pol IV switch. Specifically, Pol IV-T120P retained complete catalytic activity in vitro but, like Pol IVR and Pol IVC, failed to support Pol IV TLS function in vivo. Notably, the T120P mutation abrogated a biochemical interaction of Pol IV with Pol III that was required for Pol III-Pol IV switching. Taken together, these results support a model in which Pol III-Pol IV switching involves interaction of Pol IV with Pol III, as well as the β clamp rim and cleft. Moreover, they provide strong support for the view that Pol III-Pol IV switching represents a vitally important mechanism for regulating TLS in vivo by managing access of Pol IV to the DNA. Bacterial DNA polymerase IV (Pol IV) is capable of replicating damaged DNA via a process termed translesion DNA synthesis (TLS). Pol IV-mediated TLS can be accurate or error-prone, depending on the type of DNA damage. Errors made by Pol IV contribute to antibiotic resistance and adaptation of bacterial pathogens. In addition to catalyzing TLS, overproduction of Escherichia coli Pol IV impedes growth. In the current work, we demonstrate that both of these functions rely on the ability of Pol IV to bind the β sliding processivity clamp and switch places on DNA with the replicative Pol, Pol III. This switch requires that Pol IV contact both Pol III as well as two discrete sites on the β clamp protein. Taken together, these results provide a deeper understanding of how E. coli manages the actions of Pol III and Pol IV to coordinate high fidelity replication with potentially error-prone TLS.
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