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Peñafiel-Ayala A, Peralta-Castro A, Mora-Garduño J, García-Medel P, Zambrano-Pereira AG, Díaz-Quezada C, Abraham-Juárez MJ, Benítez-Cardoza CG, Sloan DB, Brieba LG. Plant Organellar MSH1 Is a Displacement Loop-Specific Endonuclease. PLANT & CELL PHYSIOLOGY 2024; 65:560-575. [PMID: 37756637 DOI: 10.1093/pcp/pcad112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/09/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023]
Abstract
MutS HOMOLOG 1 (MSH1) is an organellar-targeted protein that obstructs ectopic recombination and the accumulation of mutations in plant organellar genomes. MSH1 also modulates the epigenetic status of nuclear DNA, and its absence induces a variety of phenotypic responses. MSH1 is a member of the MutS family of DNA mismatch repair proteins but harbors an additional GIY-YIG nuclease domain that distinguishes it from the rest of this family. How MSH1 hampers recombination and promotes fidelity in organellar DNA inheritance is unknown. Here, we elucidate its enzymatic activities by recombinantly expressing and purifying full-length MSH1 from Arabidopsis thaliana (AtMSH1). AtMSH1 is a metalloenzyme that shows a strong binding affinity for displacement loops (D-loops). The DNA-binding abilities of AtMSH1 reside in its MutS domain and not in its GIY-YIG domain, which is the ancillary nickase of AtMSH1. In the presence of divalent metal ions, AtMSH1 selectively executes multiple incisions at D-loops, but not other DNA structures including Holliday junctions or dsDNA, regardless of the presence or absence of mismatches. The selectivity of AtMSH1 to dismantle D-loops supports the role of this enzyme in preventing recombination between short repeats. Our results suggest that plant organelles have evolved novel DNA repair routes centered around the anti-recombinogenic activity of MSH1.
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Affiliation(s)
- Alejandro Peñafiel-Ayala
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - Antolin Peralta-Castro
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - Josue Mora-Garduño
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - Paola García-Medel
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - Angie G Zambrano-Pereira
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - Corina Díaz-Quezada
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - María Jazmín Abraham-Juárez
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
| | - Claudia G Benítez-Cardoza
- Laboratorio de Investigación Bioquímica, Programa Institucional en Biomedicina Molecular ENMyH-IPN, Guillermo Massieu Helguera No. 239, La Escalera Ticoman 07320 DF, México
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Luis G Brieba
- Langebio-Cinvestav Sede Irapuato, Km. 9.6 Libramiento Norte Carretera. Irapuato-León, Irapuato, Guanajuato 36821, México
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2
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Borsellini A, Kunetsky V, Friedhoff P, Lamers MH. Cryogenic electron microscopy structures reveal how ATP and DNA binding in MutS coordinates sequential steps of DNA mismatch repair. Nat Struct Mol Biol 2022; 29:59-66. [PMID: 35013597 DOI: 10.1038/s41594-021-00707-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 11/24/2021] [Indexed: 12/18/2022]
Abstract
DNA mismatch repair detects and corrects mismatches introduced during DNA replication. The protein MutS scans for mismatches and coordinates the repair cascade. During this process, MutS undergoes multiple conformational changes in response to ATP binding, hydrolysis and release, but how ATP induces the various MutS conformations is incompletely understood. Here we present four cryogenic electron microscopy structures of Escherichia coli MutS at sequential stages of the ATP hydrolysis cycle that reveal how ATP binding and hydrolysis induce closing and opening of the MutS dimer, respectively. Biophysical analysis demonstrates how DNA binding modulates the ATPase cycle by prevention of hydrolysis during scanning and mismatch binding, while preventing ADP release in the sliding clamp state. Nucleotide release is achieved when MutS encounters single-stranded DNA that is produced during removal of the daughter strand. The combination of ATP binding and hydrolysis and its modulation by DNA enables MutS to adopt the different conformations needed to coordinate the sequential steps of the mismatch repair cascade.
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Affiliation(s)
- Alessandro Borsellini
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Peter Friedhoff
- Institute for Biochemistry, Justus-Liebig University, Giessen, Germany
| | - Meindert H Lamers
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands.
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3
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On YY, Welch M. The methylation-independent mismatch repair machinery in Pseudomonas aeruginosa. MICROBIOLOGY (READING, ENGLAND) 2021; 167. [PMID: 34882086 PMCID: PMC8744996 DOI: 10.1099/mic.0.001120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Over the last 70 years, we've all gotten used to an Escherichia coli-centric view of the microbial world. However, genomics, as well as the development of improved tools for genetic manipulation in other species, is showing us that other bugs do things differently, and that we cannot simply extrapolate from E. coli to everything else. A particularly good example of this is encountered when considering the mechanism(s) involved in DNA mismatch repair by the opportunistic human pathogen, Pseudomonas aeruginosa (PA). This is a particularly relevant phenotype to examine in PA, since defects in the mismatch repair (MMR) machinery often give rise to the property of hypermutability. This, in turn, is linked with the vertical acquisition of important pathoadaptive traits in the organism, such as antimicrobial resistance. But it turns out that PA lacks some key genes associated with MMR in E. coli, and a closer inspection of what is known (or can be inferred) about the MMR enzymology reveals profound differences compared with other, well-characterized organisms. Here, we review these differences and comment on their biological implications.
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Affiliation(s)
- Yue Yuan On
- Department of Biochemistry, Hopkins Building, Tennis Court Road, Downing Site, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Martin Welch
- Department of Biochemistry, Hopkins Building, Tennis Court Road, Downing Site, University of Cambridge, Cambridge, CB2 1QW, UK
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4
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Monakhova MV, Milakina MA, Trikin RM, Oretskaya TS, Kubareva EA. Functional Specifics of the MutL Protein of the DNA Mismatch Repair System in Different Organisms. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2020. [DOI: 10.1134/s1068162020060217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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The mutagen and carcinogen cadmium is a high-affinity inhibitor of the zinc-dependent MutLα endonuclease. Proc Natl Acad Sci U S A 2018; 115:7314-7319. [PMID: 29941579 PMCID: PMC6048502 DOI: 10.1073/pnas.1807319115] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
MutLα (MLH1-PMS2 heterodimer) is an endonuclease that acts during an early step of eukaryotic mismatch repair. We show that human MutLα endonuclease copurifies with two equivalents of bound zinc, at least one of which resides within the endonuclease active site. We also show that cadmium, a known inhibitor of zinc-dependent enzymes and a potent mutagen and carcinogen, is a high-affinity inhibitor of MutLα endonuclease and that exogenous MutLα significantly reverses the mismatch repair defect in cadmium-treated human cell nuclear extract or nuclear extract prepared from cadmium-treated cells. Because the mutagenic action of cadmium is largely due to the selective inhibition of mismatch repair, these findings suggest that MutLα is a primary cadmium target for mutagenesis and presumably, carcinogenesis as well. MutLα (MLH1-PMS2 heterodimer), which acts as a strand-directed endonuclease during the initiation of eukaryotic mismatch repair, has been postulated to function as a zinc-dependent enzyme [Kosinski J, Plotz G, Guarné A, Bujnicki JM, Friedhoff P (2008) J Mol Biol 382:610–627]. We show that human MutLα copurifies with two bound zinc ions, at least one of which resides within the endonuclease active site, and that bound zinc is required for endonuclease function. Mutagenic action of the carcinogen cadmium, a known inhibitor of zinc-dependent enzymes, is largely due to selective inhibition of mismatch repair [Jin YH, et al. (2003) Nat Genet 34:326–329]. We show that cadmium is a potent inhibitor (apparent Ki ∼ 200 nM) of MutLα endonuclease and that cadmium inhibition is reversed by zinc. We also show that inhibition of mismatch repair in cadmium-treated nuclear extract is significantly reversed by exogenous MutLα but not by MutSα (MSH2-MSH6 heterodimer) and that MutLα reversal depends on integrity of the endonuclease active site. Exogenous MutLα also partially rescues the mismatch repair defect in nuclear extract prepared from cells exposed to cadmium. These findings indicate that targeted inhibition of MutLα endonuclease contributes to cadmium inhibition of mismatch repair. This effect may play a role in the mechanism of cadmium carcinogenesis.
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6
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Wang B, Francis J, Sharma M, Law SM, Predeus AV, Feig M. Long-Range Signaling in MutS and MSH Homologs via Switching of Dynamic Communication Pathways. PLoS Comput Biol 2016; 12:e1005159. [PMID: 27768684 PMCID: PMC5074593 DOI: 10.1371/journal.pcbi.1005159] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 09/21/2016] [Indexed: 11/19/2022] Open
Abstract
Allostery is conformation regulation by propagating a signal from one site to another distal site. This study focuses on the long-range communication in DNA mismatch repair proteins MutS and its homologs where intramolecular signaling has to travel over 70 Å to couple lesion detection to ATPase activity and eventual downstream repair. Using dynamic network analysis based on extensive molecular dynamics simulations, multiple preserved communication pathways were identified that would allow such long-range signaling. The pathways appear to depend on the nucleotides bound to the ATPase domain as well as the type of DNA substrate consistent with previously proposed functional cycles of mismatch recognition and repair initiation by MutS and homologs. A mechanism is proposed where pathways are switched without major conformational rearrangements allowing for efficient long-range signaling and allostery.
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Affiliation(s)
- Beibei Wang
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Joshua Francis
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Monika Sharma
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Sean M. Law
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Alexander V. Predeus
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Michael Feig
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, United States
- * E-mail:
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7
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Ishida H, Matsumoto A. Mechanism for verification of mismatched and homoduplex DNAs by nucleotides-bound MutS analyzed by molecular dynamics simulations. Proteins 2016; 84:1287-303. [PMID: 27238299 DOI: 10.1002/prot.25077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/13/2016] [Accepted: 05/24/2016] [Indexed: 11/10/2022]
Abstract
In order to understand how MutS recognizes mismatched DNA and induces the reaction of DNA repair using ATP, the dynamics of the complexes of MutS (bound to the ADP and ATP nucleotides, or not) and DNA (with mismatched and matched base-pairs) were investigated using molecular dynamics simulations. As for DNA, the structure of the base-pairs of the homoduplex DNA which interacted with the DNA recognition site of MutS was intermittently disturbed, indicating that the homoduplex DNA was unstable. As for MutS, the disordered loops in the ATPase domains, which are considered to be necessary for the induction of DNA repair, were close to (away from) the nucleotide-binding sites in the ATPase domains when the nucleotides were (not) bound to MutS. This indicates that the ATPase domains changed their structural stability upon ATP binding using the disordered loop. Conformational analysis by principal component analysis showed that the nucleotide binding changed modes which have structurally solid ATPase domains and the large bending motion of the DNA from higher to lower frequencies. In the MutS-mismatched DNA complex bound to two nucleotides, the bending motion of the DNA at low frequency modes may play a role in triggering the formation of the sliding clamp for the following DNA-repair reaction step. Moreover, MM-PBSA/GBSA showed that the MutS-homoduplex DNA complex bound to two nucleotides was unstable because of the unfavorable interactions between MutS and DNA. This would trigger the ATP hydrolysis or separation of MutS and DNA to continue searching for mismatch base-pairs. Proteins 2016; 84:1287-1303. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Hisashi Ishida
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai Kizugawa-Shi, Kyoto, 619-0215, Japan
| | - Atsushi Matsumoto
- Quantum Beam Science Research Directorate, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai Kizugawa-Shi, Kyoto, 619-0215, Japan
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Damke PP, Dhanaraju R, Marsin S, Radicella JP, Rao DN. Mutations in the nucleotide binding and hydrolysis domains of Helicobacter pylori MutS2 lead to altered biochemical activities and inactivation of its in vivo function. BMC Microbiol 2016; 16:14. [PMID: 26843368 PMCID: PMC4739419 DOI: 10.1186/s12866-016-0629-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 01/22/2016] [Indexed: 12/17/2022] Open
Abstract
Background Helicobacter pylori MutS2 (HpMutS2), an inhibitor of recombination during transformation is a non-specific nuclease with two catalytic sites, both of which are essential for its anti-recombinase activity. Although HpMutS2 belongs to a highly conserved family of ABC transporter ATPases, the role of its ATP binding and hydrolysis activities remains elusive. Results To explore the putative role of ATP binding and hydrolysis activities of HpMutS2 we specifically generated point mutations in the nucleotide-binding Walker-A (HpMutS2-G338R) and hydrolysis Walker-B (HpMutS2-E413A) domains of the protein. Compared to wild-type protein, HpMutS2-G338R exhibited ~2.5-fold lower affinity for both ATP and ADP while ATP hydrolysis was reduced by ~3-fold. Nucleotide binding efficiencies of HpMutS2-E413A were not significantly altered; however the ATP hydrolysis was reduced by ~10-fold. Although mutations in the Walker-A and Walker-B motifs of HpMutS2 only partially reduced its ability to bind and hydrolyze ATP, we demonstrate that these mutants not only exhibited alterations in the conformation, DNA binding and nuclease activities of the protein but failed to complement the hyper-recombinant phenotype displayed by mutS2-disrupted strain of H. pylori. In addition, we show that the nucleotide cofactor modulates the conformation, DNA binding and nuclease activities of HpMutS2. Conclusions These data describe a strong crosstalk between the ATPase, DNA binding, and nuclease activities of HpMutS2. Furthermore these data show that both, ATP binding and hydrolysis activities of HpMutS2 are essential for the in vivo anti-recombinase function of the protein. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0629-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Prashant P Damke
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Rajkumar Dhanaraju
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India
| | - Stéphanie Marsin
- CEA, Institute of Cellular and Molecular Radiobiology, Fontenay aux Roses, France.,INSERM UMR967, Fontenay aux Roses, France.,Universités Paris Diderot et Paris Sud, Fontenay aux Roses, France
| | - J Pablo Radicella
- CEA, Institute of Cellular and Molecular Radiobiology, Fontenay aux Roses, France. .,INSERM UMR967, Fontenay aux Roses, France. .,Universités Paris Diderot et Paris Sud, Fontenay aux Roses, France.
| | - Desirazu N Rao
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India.
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9
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Herdendorf TJ, Nelson SW. Catalytic mechanism of bacteriophage T4 Rad50 ATP hydrolysis. Biochemistry 2014; 53:5647-60. [PMID: 25137526 DOI: 10.1021/bi500558d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Spontaneous double-strand breaks (DSBs) are one of the most deleterious forms of DNA damage, and their improper repair can lead to cellular dysfunction. The Mre11 and Rad50 proteins, a nuclease and an ATPase, respectively, form a well-conserved complex that is involved in the initial processing of DSBs. Here we examine the kinetic and catalytic mechanism of ATP hydrolysis by T4 Rad50 (gp46) in the presence and absence of Mre11 (gp47) and DNA. Single-turnover and pre-steady state kinetics on the wild-type protein indicate that the rate-limiting step for Rad50, the MR complex, and the MR-DNA complex is either chemistry or a conformational change prior to catalysis. Pre-steady state product release kinetics, coupled with viscosity steady state kinetics, also supports that the binding of DNA to the MR complex does not alter the rate-limiting step. The lack of a positive deuterium solvent isotope effect for the wild type and several active site mutants, combined with pH-rate profiles, implies that chemistry is rate-limiting and the ATPase mechanism proceeds via an asymmetric, dissociative-like transition state. Mutation of the Walker A/B and H-loop residues also affects the allosteric communication between Rad50 active sites, suggesting possible routes for cooperativity between the ATP active sites.
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Affiliation(s)
- Timothy J Herdendorf
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States
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10
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Kumar C, Eichmiller R, Wang B, Williams GM, Bianco PR, Surtees JA. ATP binding and hydrolysis by Saccharomyces cerevisiae Msh2-Msh3 are differentially modulated by mismatch and double-strand break repair DNA substrates. DNA Repair (Amst) 2014; 18:18-30. [PMID: 24746922 DOI: 10.1016/j.dnarep.2014.03.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 01/08/2023]
Abstract
In Saccharomyces cerevisiae, Msh2-Msh3-mediated mismatch repair (MMR) recognizes and targets insertion/deletion loops for repair. Msh2-Msh3 is also required for 3' non-homologous tail removal (3'NHTR) in double-strand break repair. In both pathways, Msh2-Msh3 binds double-strand/single-strand junctions and initiates repair in an ATP-dependent manner. However, we recently demonstrated that the two pathways have distinct requirements with respect to Msh2-Msh3 activities. We identified a set of aromatic residues in the nucleotide binding pocket (FLY motif) of Msh3 that, when mutated, disrupted MMR, but left 3'NHTR largely intact. One of these mutations, msh3Y942A, was predicted to disrupt the nucleotide sandwich and allow altered positioning of ATP within the pocket. To develop a mechanistic understanding of the differential requirements for ATP binding and/or hydrolysis in the two pathways, we characterized Msh2-Msh3 and Msh2-msh3Y942A ATP binding and hydrolysis activities in the presence of MMR and 3'NHTR DNA substrates. We observed distinct, substrate-dependent ATP hydrolysis and nucleotide turnover by Msh2-Msh3, indicating that the MMR and 3'NHTR DNA substrates differentially modify the ATP binding/hydrolysis activities of Msh2-Msh3. Msh2-msh3Y942A retained the ability to bind DNA and ATP but exhibited altered ATP hydrolysis and nucleotide turnover. We propose that both ATP and structure-specific repair substrates cooperate to direct Msh2-Msh3-mediated repair and suggest an explanation for the msh3Y942A separation-of-function phenotype.
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Affiliation(s)
- Charanya Kumar
- Department of Biochemistry, Immunology, University at Buffalo (SUNY), Buffalo, NY 14214, USA
| | - Robin Eichmiller
- Department of Biochemistry, Immunology, University at Buffalo (SUNY), Buffalo, NY 14214, USA
| | - Bangchen Wang
- Department of Biochemistry, Immunology, University at Buffalo (SUNY), Buffalo, NY 14214, USA
| | - Gregory M Williams
- Department of Biochemistry, Immunology, University at Buffalo (SUNY), Buffalo, NY 14214, USA
| | - Piero R Bianco
- Department of Microbiology and Immunology, University at Buffalo (SUNY), Buffalo, NY 14214, USA
| | - Jennifer A Surtees
- Department of Biochemistry, Immunology, University at Buffalo (SUNY), Buffalo, NY 14214, USA.
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11
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Lenhart JS, Pillon MC, Guarné A, Simmons LA. Trapping and visualizing intermediate steps in the mismatch repair pathwayin vivo. Mol Microbiol 2013; 90:680-98. [DOI: 10.1111/mmi.12389] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2013] [Indexed: 01/08/2023]
Affiliation(s)
- Justin S. Lenhart
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; 830 North University Ave Ann Arbor MI 48109-1048 USA
| | - Monica C. Pillon
- Department of Biochemistry and Biomedical Sciences; McMaster University; 1280 Main Street West Hamilton Ontario L8S 4K1 Canada
| | - Alba Guarné
- Department of Biochemistry and Biomedical Sciences; McMaster University; 1280 Main Street West Hamilton Ontario L8S 4K1 Canada
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; 830 North University Ave Ann Arbor MI 48109-1048 USA
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12
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Large conformational changes in MutS during DNA scanning, mismatch recognition and repair signalling. EMBO J 2012; 31:2528-40. [PMID: 22505031 DOI: 10.1038/emboj.2012.95] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 03/21/2012] [Indexed: 12/18/2022] Open
Abstract
MutS protein recognizes mispaired bases in DNA and targets them for mismatch repair. Little is known about the transient conformations of MutS as it signals initiation of repair. We have used single-molecule fluorescence resonance energy transfer (FRET) measurements to report the conformational dynamics of MutS during this process. We find that the DNA-binding domains of MutS dynamically interconvert among multiple conformations when the protein is free and while it scans homoduplex DNA. Mismatch recognition restricts MutS conformation to a single state. Steady-state measurements in the presence of nucleotides suggest that both ATP and ADP must be bound to MutS during its conversion to a sliding clamp form that signals repair. The transition from mismatch recognition to the sliding clamp occurs via two sequential conformational changes. These intermediate conformations of the MutS:DNA complex persist for seconds, providing ample opportunity for interaction with downstream proteins required for repair.
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13
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Cristóvão M, Sisamakis E, Hingorani MM, Marx AD, Jung CP, Rothwell PJ, Seidel CAM, Friedhoff P. Single-molecule multiparameter fluorescence spectroscopy reveals directional MutS binding to mismatched bases in DNA. Nucleic Acids Res 2012; 40:5448-64. [PMID: 22367846 PMCID: PMC3384296 DOI: 10.1093/nar/gks138] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mismatch repair (MMR) corrects replication errors such as mismatched bases and loops in DNA. The evolutionarily conserved dimeric MMR protein MutS recognizes mismatches by stacking a phenylalanine of one subunit against one base of the mismatched pair. In all crystal structures of G:T mismatch-bound MutS, phenylalanine is stacked against thymine. To explore whether these structures reflect directional mismatch recognition by MutS, we monitored the orientation of Escherichia coli MutS binding to mismatches by FRET and anisotropy with steady state, pre-steady state and single-molecule multiparameter fluorescence measurements in a solution. The results confirm that specifically bound MutS bends DNA at the mismatch. We found additional MutS–mismatch complexes with distinct conformations that may have functional relevance in MMR. The analysis of individual binding events reveal significant bias in MutS orientation on asymmetric mismatches (G:T versus T:G, A:C versus C:A), but not on symmetric mismatches (G:G). When MutS is blocked from binding a mismatch in the preferred orientation by positioning asymmetric mismatches near the ends of linear DNA substrates, its ability to authorize subsequent steps of MMR, such as MutH endonuclease activation, is almost abolished. These findings shed light on prerequisites for MutS interactions with other MMR proteins for repairing the appropriate DNA strand.
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Affiliation(s)
- Michele Cristóvão
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
| | - Evangelos Sisamakis
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
| | - Manju M. Hingorani
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
| | - Andreas D. Marx
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
| | - Caroline P. Jung
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
| | - Paul J. Rothwell
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
- *To whom correspondence should be addressed. Tel: +49 641 9935407; Fax: +49 641 9935409;
| | - Claus A. M. Seidel
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
- *To whom correspondence should be addressed. Tel: +49 641 9935407; Fax: +49 641 9935409;
| | - Peter Friedhoff
- Institute for Biochemistry, FB 08, Justus Liebig University, Heinrich-Buff Ring 58, D-35392 Giessen, Germany, Department of Cell Biology and Genetics, Erasmus Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands, Molecular Physical Chemistry, Heinrich-Heine University, Universitätsstrasse 1, 40225 Düsseldorf, Germany, Department of Applied Physics, Experimental Biomolecular Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Molecular Biology and Biochemistry Department, Wesleyan University, Middletown, CT 06459, USA
- *To whom correspondence should be addressed. Tel: +49 641 9935407; Fax: +49 641 9935409;
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14
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Gupta S, Gellert M, Yang W. Mechanism of mismatch recognition revealed by human MutSβ bound to unpaired DNA loops. Nat Struct Mol Biol 2011; 19:72-8. [PMID: 22179786 PMCID: PMC3252464 DOI: 10.1038/nsmb.2175] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 10/12/2011] [Indexed: 12/25/2022]
Abstract
DNA mismatch repair corrects replication errors, thus reducing mutation rates and microsatellite instability. Genetic defects in this pathway cause Lynch Syndrome and various cancers in humans. Binding of a mispaired or unpaired base by bacterial MutS and eukaryotic MutSα is well characterized. We report here crystal structures of human MutSβ complexed with DNA containing insertion-deletion loops (IDL) of 2, 3, 4, or 6 unpaired nucleotides. In contrast to eukaryotic MutSα and bacterial MutS, which bind the base of a mismatched nucleotide, MutSβ binds three phosphates in an IDL. DNA is severely bent at the IDL; unpaired bases are flipped out into the major groove and partially exposed to solvent. A normal downstream basepair can become unpaired; thereby a single unpaired base can be converted to an IDL of 2 nucleotides and recognized by MutSβ. The C-terminal dimerization domains form an integral part of the MutS structure and coordinate asymmetrical ATP hydrolysis by Msh2 and Msh3 with mismatch binding to signal for repair.
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Affiliation(s)
- Shikha Gupta
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, Maryland, USA
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15
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Law S, Feig M. Base-flipping mechanism in postmismatch recognition by MutS. Biophys J 2011; 101:2223-31. [PMID: 22067162 PMCID: PMC3207177 DOI: 10.1016/j.bpj.2011.09.045] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2011] [Revised: 09/12/2011] [Accepted: 09/13/2011] [Indexed: 11/15/2022] Open
Abstract
DNA mismatch recognition and repair is vital for preserving the fidelity of the genome. Conserved across prokaryotes and eukaryotes, MutS is the primary protein that is responsible for recognizing a variety of DNA mismatches. From molecular dynamics simulations of the Escherichia coli MutS-DNA complex, we describe significant conformational dynamics in the DNA surrounding a G·T mismatch that involves weakening of the basepair hydrogen bonding in the basepair adjacent to the mismatch and, in one simulation, complete base opening via the major groove. The energetics of base flipping was further examined with Hamiltonian replica exchange free energy calculations revealing a stable flipped-out state with an initial barrier of ~2 kcal/mol. Furthermore, we observe changes in the local DNA structure as well as in the MutS structure that appear to be correlated with base flipping. Our results suggest a role of base flipping as part of the repair initiation mechanism most likely leading to sliding-clamp formation.
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Affiliation(s)
- Sean M. Law
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Michael Feig
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan
- Department of Chemistry, Michigan State University, East Lansing, Michigan
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16
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Monti MC, Cohen SX, Fish A, Winterwerp HHK, Barendregt A, Friedhoff P, Perrakis A, Heck AJR, Sixma TK, van den Heuvel RHH, Lebbink JHG. Native mass spectrometry provides direct evidence for DNA mismatch-induced regulation of asymmetric nucleotide binding in mismatch repair protein MutS. Nucleic Acids Res 2011; 39:8052-64. [PMID: 21737427 PMCID: PMC3185415 DOI: 10.1093/nar/gkr498] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The DNA mismatch repair protein MutS recognizes mispaired bases in DNA and initiates repair in an ATP-dependent manner. Understanding of the allosteric coupling between DNA mismatch recognition and two asymmetric nucleotide binding sites at opposing sides of the MutS dimer requires identification of the relevant MutS.mmDNA.nucleotide species. Here, we use native mass spectrometry to detect simultaneous DNA mismatch binding and asymmetric nucleotide binding to Escherichia coli MutS. To resolve the small differences between macromolecular species bound to different nucleotides, we developed a likelihood based algorithm capable to deconvolute the observed spectra into individual peaks. The obtained mass resolution resolves simultaneous binding of ADP and AMP.PNP to this ABC ATPase in the absence of DNA. Mismatched DNA regulates the asymmetry in the ATPase sites; we observe a stable DNA-bound state containing a single AMP.PNP cofactor. This is the first direct evidence for such a postulated mismatch repair intermediate, and showcases the potential of native MS analysis in detecting mechanistically relevant reaction intermediates.
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Affiliation(s)
- Maria Chiara Monti
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Serge X. Cohen
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Alexander Fish
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Herrie H. K. Winterwerp
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Arjan Barendregt
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Peter Friedhoff
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Anastassis Perrakis
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
- *To whom correspondence should be addressed. Tel: +31 10 7043604; Fax +31 10 7044747;
| | - Titia K. Sixma
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Robert H. H. van den Heuvel
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Joyce H. G. Lebbink
- Biomolecular Mass Spectrometry and Proteomics Group, and Center for Biomedical Genetics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam, The Netherlands, Institut für Biochemie FB 08, Justus-Liebig-Universität, D-35392 Giessen, Germany and Department of Cell Biology and Genetics, Cancer Genomics Center and Department of Radiation Oncology, Erasmus Medical Center, Rotterdam, The Netherlands
- *To whom correspondence should be addressed. Tel: +31 10 7043604; Fax +31 10 7044747;
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17
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Lebbink JHG, Fish A, Reumer A, Natrajan G, Winterwerp HHK, Sixma TK. Magnesium coordination controls the molecular switch function of DNA mismatch repair protein MutS. J Biol Chem 2010; 285:13131-41. [PMID: 20167596 PMCID: PMC2857095 DOI: 10.1074/jbc.m109.066001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The DNA mismatch repair protein MutS acts as a molecular switch. It toggles between ADP and ATP states and is regulated by mismatched DNA. This is analogous to G-protein switches and the regulation of their “on” and “off” states by guanine exchange factors. Although GDP release in monomeric GTPases is accelerated by guanine exchange factor-induced removal of magnesium from the catalytic site, we found that release of ADP from MutS is not influenced by the metal ion in this manner. Rather, ADP release is induced by the binding of mismatched DNA at the opposite end of the protein, a long-range allosteric response resembling the mechanism of activation of heterotrimeric GTPases. Magnesium influences switching in MutS by inducing faster and tighter ATP binding, allowing rapid downstream responses. MutS mutants with decreased affinity for the metal ion are impaired in fast switching and in vivo mismatch repair. Thus, the G-proteins and MutS conceptually employ the same efficient use of the high energy cofactor: slow hydrolysis in the absence of a signal and fast conversion to the active state when required.
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Affiliation(s)
- Joyce H G Lebbink
- Division of Biochemistry and Center for Biomedical Genetics, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands.
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18
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Tian L, Hou C, Tian K, Holcomb NC, Gu L, Li GM. Mismatch recognition protein MutSbeta does not hijack (CAG)n hairpin repair in vitro. J Biol Chem 2009; 284:20452-6. [PMID: 19525234 PMCID: PMC2742808 DOI: 10.1074/jbc.c109.014977] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 06/11/2009] [Indexed: 11/06/2022] Open
Abstract
CAG repeats form stable hairpin structures, which are believed to be responsible for CAG repeat expansions associated with certain human neurological diseases. Human cells possess an accurate DNA hairpin repair system that prevents expansion of disease-associated CAG repeats. Based on transgenic animal studies, it is suggested that (CAG)(n) expansion is caused by abnormal binding of the MutSbeta mismatch recognition protein to (CAG)(n) hairpins, leading to hijacking mismatch repair function during (CAG)(n) hairpin repair. We demonstrate here that MutSbeta displays identical biochemical and biophysical activities (including ATP-provoked conformational change, ATPase, ATP binding, and ADP binding) when interacting with a (CAG)(n) hairpin and a mismatch. More importantly, our in vitro functional hairpin repair assays reveal that excess MutSbeta does not inhibit (CAG)(n) hairpin repair in HeLa nuclear extracts. Evidence presented here provides a novel view as to whether or not MutSbeta is involved in CAG repeat instability in humans.
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Affiliation(s)
- Lei Tian
- From the Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Caixia Hou
- From the Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Keli Tian
- From the Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Nathaniel C. Holcomb
- From the Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Liya Gu
- From the Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536
| | - Guo-Min Li
- From the Graduate Center for Toxicology, Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536
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19
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Spampinato CP, Gomez RL, Galles C, Lario LD. From bacteria to plants: a compendium of mismatch repair assays. Mutat Res 2009; 682:110-28. [PMID: 19622396 DOI: 10.1016/j.mrrev.2009.07.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 06/16/2009] [Accepted: 07/13/2009] [Indexed: 10/20/2022]
Abstract
Mismatch repair (MMR) system maintains genome integrity by correcting mispaired or unpaired bases which have escaped the proofreading activity of DNA polymerases. The basic features of the pathway have been highly conserved throughout evolution, although the nature and number of the proteins involved in the mechanism vary from prokaryotes to eukaryotes and even between humans and plants. Cells deficient in MMR genes have been observed to display a mutator phenotype characterized by an increased rate in spontaneous mutation, instability of microsatellite sequences and illegitimate recombination between diverged DNA sequences. Studies of the mutator phenotype have demonstrated a critical role for the MMR system in mutation avoidance and genetic stability. Here, we briefly review our current knowledge of the MMR mechanism and then focus on the in vivo biochemical and genetic assays used to investigate the function of the MMR proteins in processing DNA mismatches generated during replication and mitotic recombination in Escherichia coli, Saccharomyces cerevisiae, Homo sapiens and Arabidopsis thaliana. An overview of the biochemical assays developed to study mismatch correction in vitro is also provided.
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Affiliation(s)
- Claudia P Spampinato
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina.
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20
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Heo SD, Ku JK, Ban C. Effect of E. coli MutL on the steady-state ATPase activity of MutS in the presence of short blocked end DNAs. Biochem Biophys Res Commun 2009; 385:225-9. [DOI: 10.1016/j.bbrc.2009.05.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
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21
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Tian L, Gu L, Li GM. Distinct nucleotide binding/hydrolysis properties and molar ratio of MutSalpha and MutSbeta determine their differential mismatch binding activities. J Biol Chem 2009; 284:11557-62. [PMID: 19228687 DOI: 10.1074/jbc.m900908200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MutSalpha (MSH2/MSH6) and MutSbeta (MSH2/MSH3) are eukaryotic mismatch recognition proteins that preferentially process base-base and small insertion/deletion (ID) mispairs, respectively, despite the fact that cells contain a MutSalpha:MutSbeta ratio of 10:1. To explore the mechanism underlying the differential mismatch recognition by these two proteins, purified human MutSalpha and MutSbeta were analyzed individually and competitively for their abilities to interact with a T-G and an ID substrate. We show that MutSalpha has K(D) values of 26.5 and 38.2 nm for the G-T and ID substrates, respectively, and that MutSbeta has K(D) values of 76.5 and 23.5 nm for G-T and ID, respectively. Consistent with these results, competitive binding assays revealed the following relative binding affinities: MutSbeta-ID > MutSalpha-T-G > MutSalpha-ID >> MutSbeta-T-G. Interestingly, binding of MutSbeta to ID heteroduplexes is greatly stimulated when the MutSalpha:MutSbeta ratio is > or = 10. Distinct ATP/ADP binding and ATPase activities of MutSalpha and MutSbeta were also observed. In the absence of DNA, ADP binding and ATPase activities of MutSbeta are significantly higher than those of MutSalpha. However, interaction with DNA significantly stimulates the MutSalpha ATPase activity and reduces the MutSbeta ATPase activity, the consequence being that both proteins exhibit the same level of hydrolytic activity. We conclude that the preferential processing of base-base and ID heteroduplexes by MutSalpha and MutSbeta is determined by their significant differences in ATPase activity, ADP binding activity, and high cellular MutSalpha:MutSbeta ratio.
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Affiliation(s)
- Lei Tian
- Graduate Center for Toxicology and Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky 40536, USA
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22
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Huang SYN, Crothers DM. The role of nucleotide cofactor binding in cooperativity and specificity of MutS recognition. J Mol Biol 2008; 384:31-47. [PMID: 18773911 DOI: 10.1016/j.jmb.2008.08.052] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 08/14/2008] [Accepted: 08/20/2008] [Indexed: 10/21/2022]
Abstract
Mismatch repair (MMR) is essential for eliminating biosynthetic errors generated during replication or genetic recombination in virtually all organisms. The critical first step in Escherichia coli MMR is the specific recognition and binding of MutS to a heteroduplex, containing either a mismatch or an insertion/deletion loop of up to four nucleotides. All known MutS homologs recognize a similar broad spectrum of substrates. Binding and hydrolysis of nucleotide cofactors by the MutS-heteroduplex complex are required for downstream MMR activity, although the exact role of the nucleotide cofactors is less clear. Here, we showed that MutS bound to a 30-bp heteroduplex containing an unpaired T with a binding affinity approximately 400-fold stronger than to a 30-bp homoduplex, a much higher specificity than previously reported. The binding of nucleotide cofactors decreased both MutS specific and nonspecific binding affinity, with the latter marked by a larger drop, further increasing MutS specificity by approximately 3-fold. Kinetic studies showed that the difference in MutS K(d) for various heteroduplexes was attributable to the difference in intrinsic dissociation rate of a particular MutS-heteroduplex complex. Furthermore, the kinetic association event of MutS binding to heteroduplexes was marked by positive cooperativity. Our studies showed that the positive cooperativity in MutS binding was modulated by the binding of nucleotide cofactors. The binding of nucleotide cofactors transformed E. coli MutS tetramers, the functional unit in E. coli MMR, from a cooperative to a noncooperative binding form. Finally, we found that E. coli MutS bound to single-strand DNA with significant affinity, which could have important implication for strand discrimination in eukaryotic MMR mechanism.
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Affiliation(s)
- Shar-yin N Huang
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, P.O. Box 208114, New Haven, CT 06520-8114, USA
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23
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Miguel V, Monti MR, Argaraña CE. The role of MutS oligomers on Pseudomonas aeruginosa mismatch repair system activity. DNA Repair (Amst) 2008; 7:1799-808. [PMID: 18687413 DOI: 10.1016/j.dnarep.2008.07.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 07/09/2008] [Indexed: 11/26/2022]
Abstract
The Escherichia coli DNA Mismatch Repair (MMR) protein MutS exist as dimers and tetramers in solution, and the identification of its functional oligomeric state has been matter of extensive study. In the present work, we have analyzed the oligomerization state of MutS from Pseudomonas aeruginosa a bacterial species devoid of Dam methylation and MutH homologue. By analyzing native MutS and different mutated versions of the protein, we determined that P. aeruginosa MutS is mainly tetrameric in solution and that its oligomerization capacity is conducted as in E. coli, by the C-terminal region of the protein. The analysis of mismatch oligonucleotide binding activity showed that wild-type MutS binds to DNA as tetramer. The DNA binding activity decreased when the C-terminal region was deleted (MutSDelta798) or when a full-length MutS with tetramerization defects (MutSR842E) was tested. The ATPase activity of MutSDelta798 was similar to MutSR842E and diminished respect to the wild-type protein. Experiments carried out on a P. aeruginosa mutS strain to test the proficiency of different oligomeric versions of MutS to function in vivo showed that MutSDelta798 is not functional and that full-length dimeric version MutSR842E, is not capable of completely restoring the MMR activity of the mutant strain. Additional experiments carried out in conditions of high mutation rate induced by the base analogue 2-AP confirm that the dimeric version of MutS is not as efficient as the tetrameric wild-type protein to prevent mutations. Therefore, it is concluded that although dimeric MutS is sufficient for MMR activity, optimal activity is obtained with the tetrameric version of the protein and therefore it should be considered as the active form of MutS in P. aeruginosa.
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Affiliation(s)
- Virginia Miguel
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
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24
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Acharya S. Mutations in the signature motif in MutS affect ATP-induced clamp formation and mismatch repair. Mol Microbiol 2008; 69:1544-59. [PMID: 18673453 DOI: 10.1111/j.1365-2958.2008.06386.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SUMMARY MutS protein dimer recognizes and co-ordinates repair of DNA mismatches. Mismatch recognition by the N-terminal mismatch recognition domain and subsequent downstream signalling by MutS appear coupled to the C-terminal ATP catalytic site, Walker box, through nucleotide-mediated conformational transitions. Details of this co-ordination are not understood. The focus of this study is a conserved loop in Escherichia coli MutS that is predicted to mediate cross-talk between the two ATP catalytic sites in MutS homodimer. Mutagenesis was employed to assess the role of this loop in regulating MutS function. All mutants displayed mismatch repair defects in vivo. Biochemical characterization further revealed defects in ATP binding, ATP hydrolysis as well as effective mismatch recognition. The kinetics of initial burst of ATP hydrolysis was similar to wild type but the magnitude of the burst was reduced for the mutants. Given its proximity to the ATP bound in the opposing monomer in the crystal and its potential analogy with signature motif of ABC transporters, the results strongly suggest that the loop co-ordinates ATP binding/hydrolysis in trans by the two catalytic sites. Importantly, our data reveal that the loop plays a direct role in co-ordinating conformational changes involved in long-range communication between Walker box and mismatch recognition domains.
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Affiliation(s)
- Samir Acharya
- Department of Molecular Virology, Immunology and Medical Genetics, and Comprehensive Cancer Center, Ohio State University, Columbus, OH 43210, USA.
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25
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Steady-state ATPase activity of E. coli MutS modulated by its dissociation from heteroduplex DNA. Biochem Biophys Res Commun 2007; 364:264-9. [PMID: 17950245 DOI: 10.1016/j.bbrc.2007.09.130] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 09/28/2007] [Indexed: 11/20/2022]
Abstract
The ability of MutS to recognize mismatched DNA is required to initiate a mismatch repair (MMR) system. ATP binding and hydrolysis are essential in this process, but their role in MMR is still not fully understood. In this study, steady-state ATPase activities of MutS from Escherichia coli were investigated using the spectrophotometric method with a double end-blocked heteroduplex containing gapped bases. The ATPase activities of MutS increased as the number of gapped bases increased in a double end-blocked heteroduplex with 2-8 gapped bases in the chain, indicating that MutS dissociates from DNA when it reaches a scission during movement along the DNA. Since movement of MutS along the chain does not require extensive ATP hydrolysis and the ATPase activity is only enhanced when MutS dissociates from a heteroduplex, these results support the sliding clamp model in which ATP binding by MutS induces the formation of a hydrolysis-independent sliding clamp.
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26
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Gammie AE, Erdeniz N, Beaver J, Devlin B, Nanji A, Rose MD. Functional characterization of pathogenic human MSH2 missense mutations in Saccharomyces cerevisiae. Genetics 2007; 177:707-21. [PMID: 17720936 PMCID: PMC2034637 DOI: 10.1534/genetics.107.071084] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with defects in DNA mismatch repair. Mutations in either hMSH2 or hMLH1 underlie the majority of HNPCC cases. Approximately 25% of annotated hMSH2 disease alleles are missense mutations, resulting in a single change out of 934 amino acids. We engineered 54 missense mutations in the cognate positions in yeast MSH2 and tested for function. Of the human alleles, 55% conferred strong defects, 8% displayed intermediate defects, and 38% showed no defects in mismatch repair assays. Fifty percent of the defective alleles resulted in decreased steady-state levels of the variant Msh2 protein, and 49% of the Msh2 variants lost crucial protein-protein interactions. Finally, nine positions are predicted to influence the mismatch recognition complex ATPase activity. In summary, the missense mutations leading to loss of mismatch repair defined important structure-function relationships and the molecular analysis revealed the nature of the deficiency for Msh2 variants expressed in the tumors. Of medical relevance are 15 human alleles annotated as pathogenic in public databases that conferred no obvious defects in mismatch repair assays. This analysis underscores the importance of functional characterization of missense alleles to ensure that they are the causative factor for disease.
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Affiliation(s)
- Alison E Gammie
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1014, USA.
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27
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Mendillo ML, Putnam CD, Kolodner RD. Escherichia coli MutS tetramerization domain structure reveals that stable dimers but not tetramers are essential for DNA mismatch repair in vivo. J Biol Chem 2007; 282:16345-54. [PMID: 17426027 DOI: 10.1074/jbc.m700858200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli mispair-binding protein MutS forms dimers and tetramers in vitro, although the functional form in vivo is under debate. Here we demonstrate that the MutS tetramer is extended in solution using small angle x-ray scattering and the crystal structure of the C-terminal 34 amino acids of MutS containing the tetramer-forming domain fused to maltose-binding protein (MBP). Wild-type C-terminal MBP fusions formed tetramers and could bind MutS and MutS-MutL-DNA complexes. In contrast, D835R and R840E mutations predicted to disrupt tetrameric interactions only allowed dimerization of MBP. A chromosomal MutS truncation mutation eliminating the dimerization/tetramerization domain eliminated mismatch repair, whereas the tetramer-disrupting MutS D835R and R840E mutations only modestly affected MutS function. These results demonstrate that dimerization but not tetramerization of the MutS C terminus is essential for mismatch repair.
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MESH Headings
- Adenosine Triphosphatases/chemistry
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/metabolism
- Amino Acid Substitution
- Chromosomes, Bacterial/chemistry
- Chromosomes, Bacterial/genetics
- Chromosomes, Bacterial/metabolism
- Crystallography, X-Ray
- DNA Repair
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- Dimerization
- Escherichia coli/chemistry
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Escherichia coli Proteins/chemistry
- Escherichia coli Proteins/genetics
- Escherichia coli Proteins/metabolism
- MutL Proteins
- MutS DNA Mismatch-Binding Protein/chemistry
- MutS DNA Mismatch-Binding Protein/genetics
- MutS DNA Mismatch-Binding Protein/metabolism
- Mutation, Missense
- Protein Binding/genetics
- Protein Structure, Quaternary
- Protein Structure, Tertiary
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Affiliation(s)
- Marc L Mendillo
- Ludwig Institute for Cancer Research, Department of Medicine, University of California, San Diego School of Medicine, La Jolla, California 92093-0669, USA
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28
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Sedletska Y, Fourrier L, Malinge JM. Modulation of MutS ATP-dependent functional activities by DNA containing a cisplatin compound lesion (base damage and mismatch). J Mol Biol 2007; 369:27-40. [PMID: 17400248 DOI: 10.1016/j.jmb.2007.02.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 02/03/2007] [Accepted: 02/12/2007] [Indexed: 11/27/2022]
Abstract
DNA damage-dependent signaling by the DNA mismatch repair (MMR) system is thought to mediate cytotoxicity of the anti-tumor drug cisplatin through molecular mechanisms that could differ from those required for normal mismatch repair. The present study investigated whether ATP-dependent biochemical properties of Escherichia coli MutS protein differ when the protein interacts with a DNA oligonucleotide containing a GT mismatch versus a unique site specifically placed cisplatin compound lesion, a cisplatin 1,2-d(GpG) intrastrand cross-link with a mispaired thymine opposite the 3' platinated guanine. MutS exhibited substantial affinity for this compound lesion in hydrolytic and in non-hydrolytic conditions of ATP, contrasting with the normal nucleotide inhibition effect of mispair binding. The cisplatin compound lesion was also shown to stimulate poorly MutS ATPase activity to approach the hydrolysis rate induced by nonspecific DNA. Moreover, MutS undergoes distinct conformation changes in the presence of the compound lesion and ATP under hydrolytic conditions as shown by limited proteolysis. In the absence of MutS, the cisplatin compound lesion was shown to induce a 39 degrees rigid bending of the DNA double helix contrasting with an unbent state for DNA containing a GT mispair. Furthermore, an unbent DNA substrate containing a monofunctional adduct mimicking a cisplatin residue failed to form a persistent nucleoprotein complex with MutS in the presence of adenine nucleotide. We propose that DNA bending could play a role in MutS biochemical modulations induced by a compound lesion and that cisplatin DNA damage signaling by the MMR system could be modulated in a direct mode.
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Affiliation(s)
- Yuliya Sedletska
- Centre de Biophysique Moléculaire, CNRS, Rue Charles Sadron, 45071 Orléans Cedex 02, France
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29
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Jacobs-Palmer E, Hingorani MM. The effects of nucleotides on MutS-DNA binding kinetics clarify the role of MutS ATPase activity in mismatch repair. J Mol Biol 2006; 366:1087-98. [PMID: 17207499 PMCID: PMC1941710 DOI: 10.1016/j.jmb.2006.11.092] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 11/24/2006] [Accepted: 11/28/2006] [Indexed: 02/02/2023]
Abstract
MutS protein initiates mismatch repair with recognition of a non-Watson-Crick base-pair or base insertion/deletion site in DNA, and its interactions with DNA are modulated by ATPase activity. Here, we present a kinetic analysis of these interactions, including the effects of ATP binding and hydrolysis, reported directly from the mismatch site by 2-aminopurine fluorescence. When free of nucleotides, the Thermus aquaticus MutS dimer binds a mismatch rapidly (k(ON)=3 x 10(6) M(-1) s(-1)) and forms a stable complex with a half-life of 10 s (k(OFF)=0.07 s(-1)). When one or both nucleotide-binding sites on the MutS*mismatch complex are occupied by ATP, the complex remains fairly stable, with a half-life of 5-7 s (k(OFF)=0.1-0.14 s(-1)), although MutS(ATP) becomes incapable of (re-)binding the mismatch. When one or both nucleotide-binding sites on the MutS dimer are occupied by ADP, the MutS*mismatch complex forms rapidly (k(ON)=7.3 x 10(6) M(-1) s(-1)) and also dissociates rapidly, with a half-life of 0.4 s (k(OFF)=1.7 s(-1)). Integration of these MutS DNA-binding kinetics with previously described ATPase kinetics reveals that: (a) in the absence of a mismatch, MutS in the ADP-bound form engages in highly dynamic interactions with DNA, perhaps probing base-pairs for errors; (b) in the presence of a mismatch, MutS stabilized in the ATP-bound form releases the mismatch slowly, perhaps allowing for onsite interactions with downstream repair proteins; (c) ATP-bound MutS then moves off the mismatch, perhaps as a mobile clamp facilitating repair reactions at distant sites on DNA, until ATP is hydrolyzed (or dissociates) and the protein turns over.
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Affiliation(s)
| | - Manju M. Hingorani
- *Corresponding Author Contact information: Phone: (860) 685-2284, Fax: (860) 685-2141,
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30
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Manelyte L, Urbanke C, Giron-Monzon L, Friedhoff P. Structural and functional analysis of the MutS C-terminal tetramerization domain. Nucleic Acids Res 2006; 34:5270-9. [PMID: 17012287 PMCID: PMC1636413 DOI: 10.1093/nar/gkl489] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Escherichia coli DNA mismatch repair (MMR) protein MutS is essential for the correction of DNA replication errors. In vitro, MutS exists in a dimer/tetramer equilibrium that is converted into a monomer/dimer equilibrium upon deletion of the C-terminal 53 amino acids. In vivo and in vitro data have shown that this C-terminal domain (CTD, residues 801–853) is critical for tetramerization and the function of MutS in MMR and anti-recombination. We report the expression, purification and analysis of the E.coli MutS-CTD. Secondary structure prediction and circular dichroism suggest that the CTD is folded, with an α-helical content of 30%. Based on sedimentation equilibrium and velocity analyses, MutS-CTD forms a tetramer of asymmetric shape. A single point mutation (D835R) abolishes tetramerization but not dimerization of both MutS-CTD and full-length MutS. Interestingly, the in vivo and in vitro MMR activity of MutSCF/D835R is diminished to a similar extent as a truncated MutS variant (MutS800, residues 1–800), which lacks the CTD. Moreover, the dimer-forming MutSCF/D835R has comparable DNA binding affinity with the tetramer-forming MutS, but is impaired in mismatch-dependent activation of MutH. Our data support the hypothesis that tetramerization of MutS is important but not essential for MutS function in MMR.
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Affiliation(s)
| | - Claus Urbanke
- Medizinische Hochschule, StrukturanalyseCarl Neuberg Strasse 1, D-30625 Hannover, Germany
| | | | - Peter Friedhoff
- To whom correspondence should be addressed: Tel: +49 641 99 35407; Fax: +49 641 99 35409;
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31
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Joseph N, Duppatla V, Rao DN. Functional characterization of the DNA mismatch binding protein MutS from Haemophilus influenzae. Biochem Biophys Res Commun 2006; 334:891-900. [PMID: 16026761 DOI: 10.1016/j.bbrc.2005.06.178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Accepted: 06/29/2005] [Indexed: 10/25/2022]
Abstract
This investigation demonstrates DNA mismatch repair activity in Haemophilus influenzae cell free extracts. The mutS gene as well as purified protein of H. influenzae restored repair activity in complementation assays performed with mutS deficient Escherichia coli strain. The difference in affinity for GT and AC mismatched bases by H. influenzae MutS was reflected in the efficiency with which these DNA heteroduplexes were repaired in vitro, with GT being repaired well and AC the least. Unlike E. coli MutS, the H. influenzae homolog failed to give protein-DNA complex with homoduplex DNA. Interestingly, MutS was found to bind single-stranded DNA but with lesser affinity as compared to heteroduplex DNA. Apart from the nucleotide- and DNA-mediated conformational transitions, as monitored by circular dichroism and limited proteolysis, our data suggest a functional role when H. influenzae MutS encounters single-stranded DNA during exonucleolytic step of DNA repair process. We propose that, conformational changes in H. influenzae MutS not only modulate mismatch recognition but also trigger some of the down stream processes involved in the DNA mismatch repair process.
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Affiliation(s)
- Nimesh Joseph
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India
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32
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Mazur DJ, Mendillo ML, Kolodner RD. Inhibition of Msh6 ATPase activity by mispaired DNA induces a Msh2(ATP)-Msh6(ATP) state capable of hydrolysis-independent movement along DNA. Mol Cell 2006; 22:39-49. [PMID: 16600868 DOI: 10.1016/j.molcel.2006.02.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/25/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
Abstract
The Msh2-Msh6 heterodimer plays a key role in the repair of mispaired bases in DNA. Critical to its role in mismatch repair is the ATPase activity that resides within each subunit. Here we show that both subunits can simultaneously bind ATP and identify the Msh6 subunit as containing the high-affinity ATP binding site and Msh2 as containing a high-affinity ADP binding site. Stable binding of ATP to Msh6 causes decreased affinity of Msh2 for ADP, and binding to mispaired DNA stabilized the binding of ATP to Msh6. Our results support a model in which mispair binding encourages a dual-occupancy state with ATP bound to Msh6 and Msh2; this state supports hydrolysis-independent sliding along DNA.
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Affiliation(s)
- Dan J Mazur
- Ludwig Institute for Cancer Research, CMME 3058, 9500 Gilman Drive, La Jolla, California 92093, USA
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33
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Affiliation(s)
- Ravi R Iyer
- Department of Biochemistry and Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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34
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Yang W. Poor base stacking at DNA lesions may initiate recognition by many repair proteins. DNA Repair (Amst) 2006; 5:654-66. [PMID: 16574501 DOI: 10.1016/j.dnarep.2006.02.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 02/02/2006] [Accepted: 02/03/2006] [Indexed: 11/30/2022]
Abstract
A fundamental question in DNA repair is how a mismatched or modified base is detected when embedded in millions to billions of normal base pairs. A survey of the literature and structural database reveals a common feature in all repair protein-DNA complexes: the DNA double helix is discontinuous at a lesion site due to base unstacking, kinking and/or nucleotide extrusion. Lesions induce destabilization and distortion of short linear DNAs, and underwinding in negatively supercoiled DNA presumably could compound the reduced stability caused by a lesion. A hypothesis is thus put forward that DNA lesion recognition occurs in two steps. Repair proteins initially recognize the weakened base stacking, and thus a flexible hinge at a DNA lesion. Sampling of flexible hinges rather than all DNA base pairs can reduce the task of finding a lesion by two to three orders of magnitude, from searching millions base pairs to thousands. After the initial encounter, a repair protein scrutinizes the shape, hydrogen bonding and electrostatic potentials of bases at the flexible hinge and dissociates if it is not a correct substrate. MutS, which has a broad range of substrates, actively dissociates from non-specific binding via an ATP-dependent proofreading mechanism. A single lesion may thus be sampled by BER, NER and MMR proteins until repaired. This proposition immediately suggests a mechanism for crosstalk between different repair and signaling pathways. It also raises the possibility that sampling of a lesion by one protein could facilitate loading of another by direct protein-protein or DNA mediated interactions.
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Affiliation(s)
- Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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35
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Nag N, Krishnamoorthy G, Rao BJ. A single mismatch in the DNA induces enhanced aggregation of MutS. Hydrodynamic analyses of the protein-DNA complexes. FEBS J 2006; 272:6228-43. [PMID: 16336261 DOI: 10.1111/j.1742-4658.2005.04997.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Changes in the oligomeric status of MutS protein was probed in solution by dynamic light scattering (DLS), and corroborated by sedimentation analyses. In the absence of any nucleotide cofactor, free MutS protein [hydrodynamic radius (Rh) of 10-12 nm] shows a small increment in size (Rh 14 nm) following the addition of homoduplex DNA (121 bp), whereas the same increases to about 18-20 nm with heteroduplex DNA containing a mismatch. MutS forms large aggregates (Rh > 500 nm) with ATP, but not in the presence of a poorly hydrolysable analogue of ATP (ATPgammaS). Addition of either homo- or heteroduplex DNA attenuates the same, due to protein recruitment to DNA. However, the same protein/DNA complexes, at high concentration of ATP (10 mm), manifest an interesting property where the presence of a single mismatch provokes a much larger oligomerization of MutS on DNA (Rh > 500 nm in the presence of MutL) as compared to the normal homoduplex (Rh approximately 100-200 nm) and such mismatch induced MutS aggregation is entirely sustained by the ongoing hydrolysis of ATP in the reaction. We speculate that the surprising property of a single mismatch, in nucleating a massive aggregation of MutS encompassing the bound DNA might play an important role in mismatch repair system.
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Affiliation(s)
- Nabanita Nag
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
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36
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Lebbink JHG, Georgijevic D, Natrajan G, Fish A, Winterwerp HHK, Sixma TK, de Wind N. Dual role of MutS glutamate 38 in DNA mismatch discrimination and in the authorization of repair. EMBO J 2006; 25:409-19. [PMID: 16407973 PMCID: PMC1383519 DOI: 10.1038/sj.emboj.7600936] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Accepted: 12/05/2005] [Indexed: 01/01/2023] Open
Abstract
MutS plays a critical role in DNA mismatch repair in Escherichia coli by binding to mismatches and initiating repair in an ATP-dependent manner. Mutational analysis of a highly conserved glutamate, Glu38, has revealed its role in mismatch recognition by enabling MutS to discriminate between homoduplex and mismatched DNA. Crystal structures of MutS have shown that Glu38 forms a hydrogen bond to one of the mismatched bases. In this study, we have analyzed the crystal structures, DNA binding and the response to ATP binding of three Glu38 mutants. While confirming the role of the negative charge in initial discrimination, we show that in vivo mismatch repair can proceed even when discrimination is low. We demonstrate that the formation of a hydrogen bond by residue 38 to the mismatched base authorizes repair by inducing intramolecular signaling, which results in the inhibition of rapid hydrolysis of distally bound ATP. This allows formation of the stable MutS-ATP-DNA clamp, a key intermediate in triggering downstream repair events.
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Affiliation(s)
- Joyce H G Lebbink
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Dubravka Georgijevic
- Department of Toxicogenetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Ganesh Natrajan
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Alexander Fish
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Herrie H K Winterwerp
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Titia K Sixma
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Niels de Wind
- Department of Toxicogenetics, Leiden University Medical Center, Leiden, The Netherlands
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37
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Joseph N, Duppatla V, Rao DN. Prokaryotic DNA Mismatch Repair. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2006; 81:1-49. [PMID: 16891168 DOI: 10.1016/s0079-6603(06)81001-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Nimesh Joseph
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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38
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Antony E, Khubchandani S, Chen S, Hingorani MM. Contribution of Msh2 and Msh6 subunits to the asymmetric ATPase and DNA mismatch binding activities of Saccharomyces cerevisiae Msh2-Msh6 mismatch repair protein. DNA Repair (Amst) 2005; 5:153-62. [PMID: 16214425 PMCID: PMC4674293 DOI: 10.1016/j.dnarep.2005.08.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 08/22/2005] [Accepted: 08/25/2005] [Indexed: 12/13/2022]
Abstract
Previous analyses of both Thermus aquaticus MutS homodimer and Saccharomyces cerevisiae Msh2-Msh6 heterodimer have revealed that the subunits in these protein complexes bind and hydrolyze ATP asymmetrically, emulating their asymmetric DNA binding properties. In the MutS homodimer, one subunit (S1) binds ATP with high affinity and hydrolyzes it rapidly, while the other subunit (S2) binds ATP with lower affinity and hydrolyzes it at an apparently slower rate. Interaction of MutS with mismatched DNA results in suppression of ATP hydrolysis at S1-but which of these subunits, S1 or S2, makes specific contact with the mismatch (e.g., base stacking by a conserved phenylalanine residue) remains unknown. In order to answer this question and to clarify the links between the DNA binding and ATPase activities of each subunit in the dimer, we made mutations in the ATPase sites of Msh2 and Msh6 and assessed their impact on the activity of the Msh2-Msh6 heterodimer (in Msh2-Msh6, only Msh6 makes base specific contact with the mismatch). The key findings are: (a) Msh6 hydrolyzes ATP rapidly, and thus resembles the S1 subunit of the MutS homodimer, (b) Msh2 hydrolyzes ATP at a slower rate, and thus resembles the S2 subunit of MutS, (c) though itself an apparently weak ATPase, Msh2 has a strong influence on the ATPase activity of Msh6, (d) Msh6 binding to mismatched DNA results in suppression of rapid ATP hydrolysis, revealing a "cis" linkage between its mismatch recognition and ATPase activities, (e) the resultant Msh2-Msh6 complex, with both subunits in the ATP-bound state, exhibits altered interactions with the mismatch.
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Affiliation(s)
| | | | | | - Manju M. Hingorani
- Corresponding author. Tel.: +1 860 685 2284; fax: +1 860 685 2141. (M.M. Hingorani)
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39
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Abstract
DNA mismatch repair (MMR) is an evolutionarily conserved process that corrects mismatches generated during DNA replication and escape proofreading. MMR proteins also participate in many other DNA transactions, such that inactivation of MMR can have wide-ranging biological consequences, which can be either beneficial or detrimental. We begin this review by briefly considering the multiple functions of MMR proteins and the consequences of impaired function. We then focus on the biochemical mechanism of MMR replication errors. Emphasis is on structure-function studies of MMR proteins, on how mismatches are recognized, on the process by which the newly replicated strand is identified, and on excision of the replication error.
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Affiliation(s)
- Thomas A Kunkel
- Laboratory of Molecular Genetics and Laboratory of Structural Biology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
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40
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Yang Y, Sass LE, Du C, Hsieh P, Erie DA. Determination of protein-DNA binding constants and specificities from statistical analyses of single molecules: MutS-DNA interactions. Nucleic Acids Res 2005; 33:4322-34. [PMID: 16061937 PMCID: PMC1182163 DOI: 10.1093/nar/gki708] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Atomic force microscopy (AFM) is a powerful technique for examining the conformations of protein–DNA complexes and determining the stoichiometries and affinities of protein–protein complexes. We extend the capabilities of AFM to the determination of protein–DNA binding constants and specificities. The distribution of positions of the protein on the DNA fragments provides a direct measure of specificity and requires no knowledge of the absolute binding constants. The fractional occupancies of the protein at a given position in conjunction with the protein and DNA concentrations permit the determination of the absolute binding constants. We present the theoretical basis for this analysis and demonstrate its utility by characterizing the interaction of MutS with DNA fragments containing either no mismatch or a single mismatch. We show that MutS has significantly higher specificities for mismatches than was previously suggested from bulk studies and that the apparent low specificities are the result of high affinity binding to DNA ends. These results resolve the puzzle of the apparent low binding specificity of MutS with the expected high repair specificities. In conclusion, from a single set of AFM experiments, it is possible to determine the binding affinity, specificity and stoichiometry, as well as the conformational properties of the protein–DNA complexes.
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Affiliation(s)
- Yong Yang
- Department of Chemistry, University of North Carolina at Chapel HillChapel Hill, NC 27599-3290, USA
| | - Lauryn E. Sass
- Department of Chemistry, University of North Carolina at Chapel HillChapel Hill, NC 27599-3290, USA
| | - Chunwei Du
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD 20892, USA
| | - Peggy Hsieh
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD 20892, USA
| | - Dorothy A. Erie
- Department of Chemistry, University of North Carolina at Chapel HillChapel Hill, NC 27599-3290, USA
- Curriculum in Applied and Materials Sciences, University of North Carolina at Chapel HillChapel Hill, NC 27599-3290, USA
- To whom correspondence should be addressed. Tel: +1 919 962 6370; Fax: +1 919 966 3675;
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41
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Goldfarb T, Alani E. Distinct roles for the Saccharomyces cerevisiae mismatch repair proteins in heteroduplex rejection, mismatch repair and nonhomologous tail removal. Genetics 2005; 169:563-74. [PMID: 15489516 PMCID: PMC1449114 DOI: 10.1534/genetics.104.035204] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Accepted: 10/19/2004] [Indexed: 01/28/2023] Open
Abstract
The Saccharomyces cerevisiae mismatch repair (MMR) protein MSH6 and the SGS1 helicase were recently shown to play similarly important roles in preventing recombination between divergent DNA sequences in a single-strand annealing (SSA) assay. In contrast, MMR factors such as Mlh1p, Pms1p, and Exo1p were shown to not be required or to play only minimal roles. In this study we tested mutations that disrupt Sgs1p helicase activity, Msh2p-Msh6p mismatch recognition, and ATP binding and hydrolysis activities for their effect on preventing recombination between divergent DNA sequences (heteroduplex rejection) during SSA. The results support a model in which the Msh proteins act with Sgs1p to unwind DNA recombination intermediates containing mismatches. Importantly, msh2 mutants that displayed separation-of-function phenotypes with respect to nonhomologous tail removal during SSA and heteroduplex rejection were characterized. These studies suggest that nonhomologous tail removal is a separate function of Msh proteins that is likely to involve a distinct DNA binding activity. The involvement of Sgs1p in heteroduplex rejection but not nonhomologous tail removal further illustrates that subsets of MMR proteins collaborate with factors in different DNA repair pathways to maintain genome stability.
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Affiliation(s)
- Tamara Goldfarb
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA
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42
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Joseph N, Sawarkar R, Rao DN. DNA mismatch correction in Haemophilus influenzae: characterization of MutL, MutH and their interaction. DNA Repair (Amst) 2004; 3:1561-77. [PMID: 15474418 DOI: 10.1016/j.dnarep.2004.06.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Indexed: 11/22/2022]
Abstract
Haemophilus influenzae DNA mismatch repair proteins, MutS, MutL and MutH, are functionally characterized in this study. Introduction of mutS, mutL and mutH genes of H. influenzae resulted in complementation of the mismatch repair activity of the respective mutant strains of Escherichia coli to varying levels. DNA binding studies using H. influenzae MutH have shown that the protein is capable of binding to any DNA sequence non-specifically in a co-operative and metal independent manner. Presence of MutL and ATP in the binding reaction resulted in the formation of a more specific complex, which indicates that MutH is conferred specificity for binding hemi-methylated DNA through structural alterations mediated by its interaction with MutL. To study the role of conserved amino acids Ile213 and Leu214 in the helix at the C-terminus of MutH, they were mutated to alanine. The mutant proteins showed considerably reduced DNA binding and nicking, as well as MutL-mediated activation. MutH failed to nick HU bound DNA whereas MboI and Sau3AI, which have the same recognition sequence as MutH, efficiently cleaved the substrate. MutS ATPase activity was found to be reduced two-fold in presence of covalently closed circular duplex containing a mismatched base pair whereas, the activity was regained upon linearization of the circular duplex. This observation possibly suggests that the MutS clamps are trapped in the closed DNA heteroduplex. These studies, therefore, serve as the basis for a detailed investigation of the structure-function relationship among the protein partners of the mismatch repair pathway of H. influenzae.
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Affiliation(s)
- Nimesh Joseph
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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Antony E, Hingorani MM. Asymmetric ATP binding and hydrolysis activity of the Thermus aquaticus MutS dimer is key to modulation of its interactions with mismatched DNA. Biochemistry 2004; 43:13115-28. [PMID: 15476405 PMCID: PMC2839884 DOI: 10.1021/bi049010t] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Prokaryotic MutS and eukaryotic Msh proteins recognize base pair mismatches and insertions or deletions in DNA and initiate mismatch repair. These proteins function as dimers (and perhaps higher order oligomers) and possess an ATPase activity that is essential for DNA repair. Previous studies of Escherichia coli MutS and eukaryotic Msh2-Msh6 proteins have revealed asymmetry within the dimer with respect to both DNA binding and ATPase activities. We have found the Thermus aquaticus MutS protein amenable to detailed investigation of the nature and role of this asymmetry. Here, we show that (a) in a MutS dimer one subunit (S1) binds nucleotide with high affinity and the other (S2) with 10-fold weaker affinity, (b) S1 hydrolyzes ATP rapidly while S2 hydrolyzes ATP at a 30-50-fold slower rate, (c) mismatched DNA binding to MutS inhibits ATP hydrolysis at S1 but slow hydrolysis continues at S2, and (d) interaction between mismatched DNA and MutS is weakened when both subunits are occupied by ATP but remains stable when S1 is occupied by ATP and S2 by ADP. These results reveal key MutS species in the ATPase pathway; S1(ADP)-S2(ATP) is formed preferentially in the absence of DNA or in the presence of fully matched DNA, while S1(ATP)-S2(ATP) and S1(ATP)-S2(ADP) are formed preferentially in the presence of mismatched DNA. These MutS species exhibit differences in interaction with mismatched DNA that are likely important for the mechanism of MutS action in DNA repair.
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Lamers MH, Georgijevic D, Lebbink JH, Winterwerp HHK, Agianian B, de Wind N, Sixma TK. ATP increases the affinity between MutS ATPase domains. Implications for ATP hydrolysis and conformational changes. J Biol Chem 2004; 279:43879-85. [PMID: 15297450 DOI: 10.1074/jbc.m406380200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
MutS is the key protein of the Escherichia coli DNA mismatch repair system. It recognizes mispaired and unpaired bases and has intrinsic ATPase activity. ATP binding after mismatch recognition by MutS serves as a switch that enables MutL binding and the subsequent initiation of mismatch repair. However, the mechanism of this switch is poorly understood. We have investigated the effects of ATP binding on the MutS structure. Crystallographic studies of ATP-soaked crystals of MutS show a trapped intermediate, with ATP in the nucleotide-binding site. Local rearrangements of several residues around the nucleotide-binding site suggest a movement of the two ATPase domains of the MutS dimer toward each other. Analytical ultracentrifugation experiments confirm such a rearrangement, showing increased affinity between the ATPase domains upon ATP binding and decreased affinity in the presence of ADP. Mutations of specific residues in the nucleotide-binding domain reduce the dimer affinity of the ATPase domains. In addition, ATP-induced release of DNA is strongly reduced in these mutants, suggesting that the two activities are coupled. Hence, it seems plausible that modulation of the affinity between ATPase domains is the driving force for conformational changes in the MutS dimer. These changes are driven by distinct amino acids in the nucleotide-binding site and form the basis for long-range interactions between the ATPase domains and DNA-binding domains and subsequent binding of MutL and initiation of mismatch repair.
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Affiliation(s)
- Meindert H Lamers
- Division of Molecular Carcinogenesis, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam
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Martik D, Baitinger C, Modrich P. Differential specificities and simultaneous occupancy of human MutSalpha nucleotide binding sites. J Biol Chem 2004; 279:28402-10. [PMID: 15105434 DOI: 10.1074/jbc.m312108200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have examined the permissible nucleotide occupancy states of human MutSalpha. The MSH2.MSH6 heterodimer binds 1 mol of ADP and 1 mol of adenosine 5'-O-(thiotriphosphate) (ATPgammaS), with a K(d) for each nucleotide of about 1 microm. Anisotropy measurements using BODIPY TR and BODIPY FL fluorescent derivatives of ADP and 5'-adenylyl-beta,gamma-imidodiphosphate (AMPPNP) also indicate an interaction stoichiometry of 1 mol of ADP and 1 mol of triphosphate analogue per MutSalpha heterodimer. Di- and triphosphate sites can be simultaneously occupied as judged by sequential filling of the two binding site classes with differentially radiolabeled ADP and ATPgammaS and by fluorescence resonance energy transfer between BODIPY TR- and BODIPY FL-labeled ADP and AMPPNP. ATP hydrolysis by MutSalpha is accompanied by a pre-steady-state burst of ADP formation, and analysis of MutSalpha-bound nucleotide during the first turnover has demonstrated the presence of both ADP and ATP. Simultaneous presence of ADP and a nonhydrolyzable ATP analogue modulates MutSalpha.heteroduplex interaction in a manner that is distinct from that observed in the presence of ADP or nonhydrolyzable triphosphate alone, and it is unlikely that this effect is due to the presence of a mixed population of binary complexes between MutSalpha and ADP or a triphosphate analogue. These findings imply that MutSalpha has two nucleotide binding sites with differential specificities for ADP and ATP and suggest that the ADP.MutSalpha.ATP ternary complex has an important role in mismatch repair.
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Affiliation(s)
- Diana Martik
- Department of Biochemistry and Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
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Abstract
DNA mismatch repair (MMR) guards the integrity of the genome in virtually all cells. It contributes about 1000-fold to the overall fidelity of replication and targets mispaired bases that arise through replication errors, during homologous recombination, and as a result of DNA damage. Cells deficient in MMR have a mutator phenotype in which the rate of spontaneous mutation is greatly elevated, and they frequently exhibit microsatellite instability at mono- and dinucleotide repeats. The importance of MMR in mutation avoidance is highlighted by the finding that defects in MMR predispose individuals to hereditary nonpolyposis colorectal cancer. In addition to its role in postreplication repair, the MMR machinery serves to police homologous recombination events and acts as a barrier to genetic exchange between species.
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Affiliation(s)
- Mark J Schofield
- Genetics and Biochemistry Branch, National Institute of Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Baitinger C, Burdett V, Modrich P. Hydrolytically Deficient MutS E694A Is Defective in the MutL-dependent Activation of MutH and in the Mismatch-dependent Assembly of the MutS · MutL · Heteroduplex Complex. J Biol Chem 2003; 278:49505-11. [PMID: 14506224 DOI: 10.1074/jbc.m308738200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The roles of ATP binding and hydrolysis by MutS in mismatch repair are poorly understood. MutS E694A, in which Glu-694 of the Walker B motif is substituted with alanine, is defective in hydrolysis of bound ATP and has been reported to support MutL-dependent activation of the MutH d(GATC) endonuclease in a trans DNA activation assay (Junop, M. S., Obmolova, G., Rausch, K., Hsieh, P., and Yang, W. (2001) Mol. Cell 7, 1-12). Because the MutH trans activation assay used in these previous studies was characterized by high background and low efficiency, we have re-evaluated the activities of MutS E694A. In contrast to native MutS, which can be isolated in a nucleotide-free form, purified MutS E694A contains 1.0 mol of bound ATP per dimer equivalent, and substoichiometric levels of bound ADP (0.08-0.58 mol/dimer), consistent with the suggestion that the ADP.MutS.ATP complex comprises a significant fraction of the protein in solution (Bjornson, K. P. and Modrich, P. (2003) J. Biol. Chem. 278, 18557-18562). In the presence of Mg2+, endogenous ATP is hydrolyzed with a rate constant of 0.12 min-1 at 30 degrees C, and hydrolysis yields a protein that displays increased specificity for heteroduplex DNA. As observed with wild type MutS, ATP can promote release of MutS E694A from a mismatch. However, the mutant protein is defective in the methyl-directed, mismatch- and MutL-dependent cis activation of MutH endonuclease on a 6.4-kilobase pair heteroduplex, displaying only 1 to 2% of the activity of wild type MutS. The mutant protein also fails to support normal assembly of the MutS.MutL.DNA ternary complex. Although a putative ternary complex can be observed in the presence of MutS E694A, assembly of this structure displays little if any dependence on a mismatched base pair.
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Affiliation(s)
- Celia Baitinger
- Howard Hughes Medical Institute and Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Wang H, Yang Y, Schofield MJ, Du C, Fridman Y, Lee SD, Larson ED, Drummond JT, Alani E, Hsieh P, Erie DA. DNA bending and unbending by MutS govern mismatch recognition and specificity. Proc Natl Acad Sci U S A 2003; 100:14822-7. [PMID: 14634210 PMCID: PMC299810 DOI: 10.1073/pnas.2433654100] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA mismatch repair is central to the maintenance of genomic stability. It is initiated by the recognition of base-base mismatches and insertion/deletion loops by the family of MutS proteins. Subsequently, ATP induces a unique conformational change in the MutS-mismatch complex but not in the MutS-homoduplex complex that sets off the cascade of events that leads to repair. To gain insight into the mechanism by which MutS discriminates between mismatch and homoduplex DNA, we have examined the conformations of specific and nonspecific MutS-DNA complexes by using atomic force microscopy. Interestingly, MutS-DNA complexes exhibit a single population of conformations, in which the DNA is bent at homoduplex sites, but two populations of conformations, bent and unbent, at mismatch sites. These results suggest that the specific recognition complex is one in which the DNA is unbent. Combining our results with existing biochemical and crystallographic data leads us to propose that MutS: (i) binds to DNA nonspecifically and bends it in search of a mismatch; (ii) on specific recognition of a mismatch, undergoes a conformational change to an initial recognition complex in which the DNA is kinked, with interactions similar to those in the published crystal structures; and (iii) finally undergoes a further conformational change to the ultimate recognition complex in which the DNA is unbent. Our results provide a structural explanation for the long-standing question of how MutS achieves mismatch repair specificity.
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Affiliation(s)
- Hong Wang
- Department of Chemistry and Curriculum in Applied and Materials Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
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Bjornson KP, Blackwell LJ, Sage H, Baitinger C, Allen D, Modrich P. Assembly and molecular activities of the MutS tetramer. J Biol Chem 2003; 278:34667-73. [PMID: 12829697 DOI: 10.1074/jbc.m305513200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Analytical equilibrium ultracentrifugation indicates that Escherichia coli MutS exists as an equilibrating mixture of dimers and tetramers. The association constant for the dimer-to-tetramer transition is 2.1 x 10(7) M-1, indicating that the protein would consist of both dimers and tetramers at physiological concentrations. The carboxyl terminus of MutS is required for tetramer assembly because a previously described 53-amino acid carboxyl-terminal truncation (MutS800) forms a limiting species of a dimer (Obmolova, G., Ban, C., Hsieh, P., and Yang, W. (2000) Nature 407, 703-710; Lamers, M. H., Perrakis, A., Enzlin, J. H., Winterwerp, H. H., de Wind, N., and Sixma, T. K. (2000) Nature 407, 711-717). MutS800 binds a 20-base pair heteroduplex an order of magnitude more weakly than full-length MutS, and at saturating protein concentrations, the heteroduplex-bound mass observed with MutS800 is only half that observed with the full length protein, indicating that the subunit copy number of heteroduplex-bound MutS is twice that of MutS800. Analytical equilibrium ultracentrifugation using a fluorescein-tagged 20-base pair heteroduplex demonstrated that native MutS forms a tetramer on this single site-sized heteroduplex DNA. Equilibrium fluorescence experiments indicated that dimer-to-tetramer assembly promotes mismatch binding by MutS and that the tetramer can bind only a single heteroduplex molecule, implying nonequivalence of the two dimers within the tetramer. Compared with native MutS, the ability of MutS800 to promote MutL-dependent activation of MutH is substantially reduced.
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Affiliation(s)
- Keith P Bjornson
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Kijas AW, Studamire B, Alani E. Msh2 separation of function mutations confer defects in the initiation steps of mismatch repair. J Mol Biol 2003; 331:123-38. [PMID: 12875840 DOI: 10.1016/s0022-2836(03)00694-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In eukaryotes the MSH2-MSH3 and MSH2-MSH6 heterodimers initiate mismatch repair (MMR) by recognizing and binding to DNA mismatches. The MLH1-PMS1 heterodimer then interacts with the MSH proteins at or near the mismatch site and is thought to act as a mediator to recruit downstream repair proteins. Here we analyzed five msh2 mutants that are functional in removing 3' non-homologous tails during double-strand break repair but are completely defective in MMR. Because non-homologous tail removal does not require MSH6, MLH1, or PMS1 functions, a characterization of the msh2 separation of function alleles should provide insights into early steps in MMR. Using the Taq MutS crystal structure as a model, three of the msh2 mutations, msh2-S561P, msh2-K564E, msh2-G566D, were found to map to a domain in MutS involved in stabilizing mismatch binding. Gel mobility shift and DNase I footprinting assays showed that two of these mutations conferred strong defects on MSH2-MSH6 mismatch binding. The other two mutations, msh2-S656P and msh2-R730W, mapped to the ATPase domain. DNase I footprinting, ATP hydrolysis, ATP binding, and MLH1-PMS1 interaction assays indicated that the msh2-S656P mutation caused defects in ATP-dependent dissociation of MSH2-MSH6 from mismatch DNA and in interactions between MSH2-MSH6 and MLH1-PMS1. In contrast, the msh2-R730W mutation disrupted MSH2-MSH6 ATPase activity but did not strongly affect ATP binding or interactions with MLH1-PMS1. These results support a model in which MMR can be dissected into discrete steps: stable mismatch binding and sensing, MLH1-PMS1 recruitment, and recycling of MMR components.
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Affiliation(s)
- Amanda Wraith Kijas
- Department of Molecular Biology and Genetics, Cornell University, 459 Biotech Building, Ithaca, NY 14853-2703, USA
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