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D'Arcy BM, Arrington J, Weisman J, McClellan SB, Vandana , Yang Z, Deivanayagam C, Blount J, Prakash A. PMS2 variant results in loss of ATPase activity without compromising mismatch repair. Mol Genet Genomic Med 2022; 10:e1908. [PMID: 35189042 PMCID: PMC9034662 DOI: 10.1002/mgg3.1908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 02/08/2022] [Indexed: 02/01/2023] Open
Abstract
Hereditary cancer syndromes account for approximately 5%-10% of all diagnosed cancer cases. Lynch syndrome (LS) is an autosomal dominant hereditary cancer condition that predisposes individuals to an elevated lifetime risk for developing colorectal, endometrial, and other cancers. LS results from a pathogenic mutation in one of four mismatch repair (MMR) genes (MSH2, MSH6, MLH1, and PMS2). The diagnosis of LS is often challenged by the identification of missense mutations, termed variants of uncertain significance, whose functional effect on the protein is not known. Of the eight PMS2 variants initially selected for this study, we identified a variant within the N-terminal domain where asparagine 335 is mutated to serine, p.Asn335Ser, which lacked ATPase activity, yet appears to be proficient in MMR. To expand our understanding of this functional dichotomy, we performed biophysical and structural studies, and noted that p.Asn335Ser binds to ATP but is unable to hydrolyze it to ADP. To examine the impact of p.Asn335Ser on MMR, we developed a novel in-cell fluorescent-based microsatellite instability reporter that revealed p.Asn335Ser maintained genomic stability. We conclude that in the absence of gross structural changes, PMS2 ATP hydrolysis is not necessary for proficient MMR and that the ATPase deficient p.Asn335Ser variant is likely benign.
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Affiliation(s)
- Brandon M. D'Arcy
- Mitchell Cancer InstituteUniversity of South Alabama HealthMobileAlabamaUSA
- Department of Biochemistry and Molecular BiologyUniversity of South AlabamaMobileAlabamaUSA
| | - Jennifer Arrington
- Mitchell Cancer InstituteUniversity of South Alabama HealthMobileAlabamaUSA
- Department of Biochemistry and Molecular BiologyUniversity of South AlabamaMobileAlabamaUSA
| | - Justin Weisman
- Mitchell Cancer InstituteUniversity of South Alabama HealthMobileAlabamaUSA
- Department of Biochemistry and Molecular BiologyUniversity of South AlabamaMobileAlabamaUSA
| | - Steven B. McClellan
- Mitchell Cancer InstituteUniversity of South Alabama HealthMobileAlabamaUSA
- Flow Cytometry Shared Resource LabMitchell Cancer InstituteMobileAlabamaUSA
| | - Vandana
- Mitchell Cancer InstituteUniversity of South Alabama HealthMobileAlabamaUSA
- Department of Biochemistry and Molecular BiologyUniversity of South AlabamaMobileAlabamaUSA
| | - Zhengrong Yang
- Department of Biochemistry and Molecular GeneticsSchool of Medicine University of Alabama at BirminghamBirminghamAlabamaUSA
| | - Champion Deivanayagam
- Department of Biochemistry and Molecular GeneticsSchool of Medicine University of Alabama at BirminghamBirminghamAlabamaUSA
| | | | - Aishwarya Prakash
- Mitchell Cancer InstituteUniversity of South Alabama HealthMobileAlabamaUSA
- Department of Biochemistry and Molecular BiologyUniversity of South AlabamaMobileAlabamaUSA
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2
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Biswas K, Couillard M, Cavallone L, Burkett S, Stauffer S, Martin BK, Southon E, Reid S, Plona TM, Baugher RN, Mellott SD, Pike KM, Albaugh ME, Maedler-Kron C, Hamel N, Tessarollo L, Marcus V, Foulkes WD, Sharan SK. A novel mouse model of PMS2 founder mutation that causes mismatch repair defect due to aberrant splicing. Cell Death Dis 2021; 12:838. [PMID: 34489406 PMCID: PMC8421400 DOI: 10.1038/s41419-021-04130-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 08/10/2021] [Accepted: 08/18/2021] [Indexed: 11/09/2022]
Abstract
Hereditary non-polyposis colorectal cancer, now known as Lynch syndrome (LS) is one of the most common cancer predisposition syndromes and is caused by germline pathogenic variants (GPVs) in DNA mismatch repair (MMR) genes. A common founder GPV in PMS2 in the Canadian Inuit population, NM_000535.5: c.2002A>G, leads to a benign missense (p.I668V) but also acts as a de novo splice site that creates a 5 bp deletion resulting in a truncated protein (p.I668*). Individuals homozygous for this GPV are predisposed to atypical constitutional MMR deficiency with a delayed onset of first primary malignancy. We have generated mice with an equivalent germline mutation (Pms2c.1993A>G) and demonstrate that it results in a splicing defect similar to those observed in humans. Homozygous mutant mice are viable like the Pms2 null mice. However, unlike the Pms2 null mice, these mutant mice are fertile, like humans homozygous for this variant. Furthermore, these mice exhibit a significant increase in microsatellite instability and intestinal adenomas on an Apc mutant background. Rectification of the splicing defect in human and murine fibroblasts using antisense morpholinos suggests that this novel mouse model can be valuable in evaluating the efficacy aimed at targeting the splicing defect in PMS2 that is highly prevalent among the Canadian Inuits.
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Affiliation(s)
- Kajal Biswas
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Martin Couillard
- The Lady Davis Institute of the Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Luca Cavallone
- The Lady Davis Institute of the Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Sandra Burkett
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Stacey Stauffer
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Betty K Martin
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Eileen Southon
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Susan Reid
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Teri M Plona
- CLIA Molecular Diagnostics Laboratory, Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Ryan N Baugher
- CLIA Molecular Diagnostics Laboratory, Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Stephanie D Mellott
- CLIA Molecular Diagnostics Laboratory, Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Kristen M Pike
- CLIA Molecular Diagnostics Laboratory, Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Mary E Albaugh
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
- Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | | | - Nancy Hamel
- Department of Oncology, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Lino Tessarollo
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Victoria Marcus
- Department of Pathology, McGill University, Montreal, QC, Canada
| | - William D Foulkes
- The Lady Davis Institute of the Jewish General Hospital, McGill University, Montreal, QC, Canada
- Department of Oncology, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- Department of Medical Genetics, Jewish General Hospital, McGill University, Montreal, QC, H3T 1E2, Canada
- Department of Medical Genetics and Cancer Research Program, Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3JI, Canada
| | - Shyam K Sharan
- Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA.
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3
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Rahman MM, Mohiuddin M, Shamima Keka I, Yamada K, Tsuda M, Sasanuma H, Andreani J, Guerois R, Borde V, Charbonnier JB, Takeda S. Genetic evidence for the involvement of mismatch repair proteins, PMS2 and MLH3, in a late step of homologous recombination. J Biol Chem 2021; 295:17460-17475. [PMID: 33453991 DOI: 10.1074/jbc.ra120.013521] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 09/28/2020] [Indexed: 12/15/2022] Open
Abstract
Homologous recombination (HR) repairs DNA double-strand breaks using intact homologous sequences as template DNA. Broken DNA and intact homologous sequences form joint molecules (JMs), including Holliday junctions (HJs), as HR intermediates. HJs are resolved to form crossover and noncrossover products. A mismatch repair factor, MLH3 endonuclease, produces the majority of crossovers during meiotic HR, but it remains elusive whether mismatch repair factors promote HR in nonmeiotic cells. We disrupted genes encoding the MLH3 and PMS2 endonucleases in the human B cell line, TK6, generating null MLH3-/- and PMS2-/- mutant cells. We also inserted point mutations into the endonuclease motif of MLH3 and PMS2 genes, generating endonuclease death MLH3DN/DN and PMS2EK/EK cells. MLH3-/- and MLH3DN/DN cells showed a very similar phenotype, a 2.5-fold decrease in the frequency of heteroallelic HR-dependent repair of restriction enzyme-induced double-strand breaks. PMS2-/- and PMS2EK/EK cells showed a phenotype very similar to that of the MLH3 mutants. These data indicate that MLH3 and PMS2 promote HR as an endonuclease. The MLH3DN/DN and PMS2EK/EK mutations had an additive effect on the heteroallelic HR. MLH3DN/DN/PMS2EK/EK cells showed normal kinetics of γ-irradiation-induced Rad51 foci but a significant delay in the resolution of Rad51 foci and a 3-fold decrease in the number of cisplatin-induced sister chromatid exchanges. The ectopic expression of the Gen1 HJ re-solvase partially reversed the defective heteroallelic HR of MLH3DN/DN/PMS2EK/EK cells. Taken together, we propose that MLH3 and PMS2 promote HR as endonucleases, most likely by processing JMs in mammalian somatic cells.
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Affiliation(s)
- Md Maminur Rahman
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Mohiuddin Mohiuddin
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Islam Shamima Keka
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kousei Yamada
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masataka Tsuda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroyuki Sasanuma
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Jessica Andreani
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique (CEA), CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Raphael Guerois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique (CEA), CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Valerie Borde
- Institut Curie, CNRS, UMR3244, PSL Research University, Paris, France
| | - Jean-Baptiste Charbonnier
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique (CEA), CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
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Hereditary brain tumor with a homozygous germline mutation in PMS2: pedigree analysis and prenatal screening in a family with constitutional mismatch repair deficiency (CMMRD) syndrome. Fam Cancer 2019; 18:261-265. [PMID: 30478739 DOI: 10.1007/s10689-018-0112-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Precise genetic counseling and prenatal diagnosis are often hindered by incomplete penetrance of risk variance and complex patterns of inheritance. Here, we performed a clinical and genetic study of a five-generation Pakistani family with a history of multiple cases of childhood brain tumors. Six affected individuals died of brain tumors at very early ages and three were confirmed as having a homozygous mutation in exon 6 of the PMS2 gene (c.543delT). Fifteen members of the family were identified as heterozygous carriers of this mutation with a lack of cancer incidence. Both clinical manifestations and genetic test results of brain tumor patients in the family support the diagnosis of constitutional mismatch repair deficiency (CMMRD) syndrome, a condition in which individuals carry homozygous germline mutations in mismatch repair machinery genes with an early onset of malignancies such as glioma. This information was used to guide prenatal diagnosis with genetic testing on chorionic villus samples for the family. This is the first report of prenatal genetic diagnosis of hereditary brain tumor.
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5
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Kadyrova LY, Kadyrov FA. Endonuclease activities of MutLα and its homologs in DNA mismatch repair. DNA Repair (Amst) 2016; 38:42-49. [PMID: 26719141 PMCID: PMC4820397 DOI: 10.1016/j.dnarep.2015.11.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 08/26/2015] [Accepted: 11/30/2015] [Indexed: 12/28/2022]
Abstract
MutLα is a key component of the DNA mismatch repair system in eukaryotes. The DNA mismatch repair system has several genetic stabilization functions. Of these functions, DNA mismatch repair is the major one. The loss of MutLα abolishes DNA mismatch repair, thereby predisposing humans to cancer. MutLα has an endonuclease activity that is required for DNA mismatch repair. The endonuclease activity of MutLα depends on the DQHA(X)2E(X)4E motif which is a part of the active site of the nuclease. This motif is also present in many bacterial MutL and eukaryotic MutLγ proteins, DNA mismatch repair system factors that are homologous to MutLα. Recent studies have shown that yeast MutLγ and several MutL proteins containing the DQHA(X)2E(X)4E motif possess endonuclease activities. Here, we review the endonuclease activities of MutLα and its homologs in the context of DNA mismatch repair.
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Affiliation(s)
- Lyudmila Y Kadyrova
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Farid A Kadyrov
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.
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Peña-Diaz J, Rasmussen LJ. Approaches to diagnose DNA mismatch repair gene defects in cancer. DNA Repair (Amst) 2015; 38:147-154. [PMID: 26708048 DOI: 10.1016/j.dnarep.2015.11.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 08/12/2015] [Accepted: 11/30/2015] [Indexed: 12/12/2022]
Abstract
The DNA repair pathway mismatch repair (MMR) is responsible for the recognition and correction of DNA biosynthetic errors caused by inaccurate nucleotide incorporation during replication. Faulty MMR leads to failure to address the mispairs or insertion deletion loops (IDLs) left behind by the replicative polymerases and results in increased mutation load at the genome. The realization that defective MMR leads to a hypermutation phenotype and increased risk of tumorigenesis highlights the relevance of this pathway for human disease. The association of MMR defects with increased risk of cancer development was first observed in colorectal cancer patients that carried inactivating germline mutations in MMR genes and the disease was named as hereditary non-polyposis colorectal cancer (HNPCC). Currently, a growing list of cancers is found to be MMR defective and HNPCC has been renamed Lynch syndrome (LS) partly to include the associated risk of developing extra-colonic cancers. In addition, a number of non-hereditary, mostly epigenetic, alterations of MMR genes have been described in sporadic tumors. Besides conferring a strong cancer predisposition, genetic or epigenetic inactivation of MMR genes also renders cells resistant to some chemotherapeutic agents. Therefore, diagnosis of MMR deficiency has important implications for the management of the patients, the surveillance of their relatives in the case of LS and for the choice of treatment. Some of the alterations found in MMR genes have already been well defined and their pathogenicity assessed. Despite this substantial wealth of knowledge, the effects of a large number of alterations remain uncharacterized (variants of uncertain significance, VUSs). The advent of personalized genomics is likely to increase the list of VUSs found in MMR genes and anticipates the need of diagnostic tools for rapid assessment of their pathogenicity. This review describes current tools and future strategies for addressing the relevance of MMR gene alterations in human disease.
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Affiliation(s)
- Javier Peña-Diaz
- Center for Healthy Aging, Department of Neuroscience and Pharmacology, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| | - Lene Juel Rasmussen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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7
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Abstract
DNA mismatch repair (MMR) identifies and corrects errors made during replication. In all organisms except those expressing MutH, interactions between a DNA mismatch, MutS, MutL, and the replication processivity factor (β-clamp or PCNA) activate the latent MutL endonuclease to nick the error-containing daughter strand. This nick provides an entry point for downstream repair proteins. Despite the well-established significance of strand-specific nicking in MMR, the mechanism(s) by which MutS and MutL assemble on mismatch DNA to allow the subsequent activation of MutL's endonuclease activity by β-clamp/PCNA remains elusive. In both prokaryotes and eukaryotes, MutS homologs undergo conformational changes to a mobile clamp state that can move away from the mismatch. However, the function of this MutS mobile clamp is unknown. Furthermore, whether the interaction with MutL leads to a mobile MutS-MutL complex or a mismatch-localized complex is hotly debated. We used single molecule FRET to determine that Thermus aquaticus MutL traps MutS at a DNA mismatch after recognition but before its conversion to a sliding clamp. Rather than a clamp, a conformationally dynamic protein assembly typically containing more MutL than MutS is formed at the mismatch. This complex provides a local marker where interaction with β-clamp/PCNA could distinguish parent/daughter strand identity. Our finding that MutL fundamentally changes MutS actions following mismatch detection reframes current thinking on MMR signaling processes critical for genomic stability.
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8
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The effect of genotypes and parent of origin on cancer risk and age of cancer development in PMS2 mutation carriers. Genet Med 2015; 18:405-9. [PMID: 26110232 DOI: 10.1038/gim.2015.83] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/15/2015] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Lynch syndrome (LS), a heritable disorder with an increased risk of primarily colorectal cancer (CRC) and endometrial cancer (EC), can be caused by mutations in the PMS2 gene. We wished to establish whether genotype and/or parent-of-origin effects (POE) explain (part of) the reported variability in severity of the phenotype. METHODS European PMS2 mutation carriers (n = 381) were grouped and compared based on RNA expression and whether the mutation was inherited paternally or maternally. RESULTS Mutation carriers with loss of RNA expression (group 1) had a significantly lower age at CRC diagnosis (51.1 years vs. 60.0 years, P = 0.035) and a lower age at EC diagnosis (55.8 years vs. 61.0 years, P = 0.2, nonsignificant) compared with group 2 (retention of RNA expression). Furthermore, group 1 showed slightly higher, but nonsignificant, hazard ratios (HRs) for both CRC (HR: 1.31, P = 0.38) and EC (HR: 1.22, P = 0.72). No evidence for a significant parent-of-origin effect was found for either CRC or EC. CONCLUSIONS PMS2 mutation carriers with retention of RNA expression developed CRC 9 years later than those with loss of RNA expression. If confirmed, this finding would justify a delay in surveillance for these cases. Cancer risk was not influenced by a parent-of-origin effect.Genet Med 18 4, 405-409.
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Abstract
Three processes act in series to accurately replicate the eukaryotic nuclear genome. The major replicative DNA polymerases strongly prevent mismatch formation, occasional mismatches that do form are proofread during replication, and rare mismatches that escape proofreading are corrected by mismatch repair (MMR). This review focuses on MMR in light of increasing knowledge about nuclear DNA replication enzymology and the rate and specificity with which mismatches are generated during leading- and lagging-strand replication. We consider differences in MMR efficiency in relation to mismatch recognition, signaling to direct MMR to the nascent strand, mismatch removal, and the timing of MMR. These studies are refining our understanding of relationships between generating and repairing replication errors to achieve accurate replication of both DNA strands of the nuclear genome.
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Affiliation(s)
- Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina 27709;
| | - Dorothy A Erie
- Department of Chemistry and Curriculum in Applied Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599-3290;
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10
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Goellner EM, Smith CE, Campbell CS, Hombauer H, Desai A, Putnam CD, Kolodner RD. PCNA and Msh2-Msh6 activate an Mlh1-Pms1 endonuclease pathway required for Exo1-independent mismatch repair. Mol Cell 2014; 55:291-304. [PMID: 24981171 DOI: 10.1016/j.molcel.2014.04.034] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/09/2014] [Accepted: 04/28/2014] [Indexed: 11/17/2022]
Abstract
Genetic evidence has implicated multiple pathways in eukaryotic DNA mismatch repair (MMR) downstream of mispair recognition and Mlh1-Pms1 recruitment, including Exonuclease 1 (Exo1)-dependent and -independent pathways. We identified 14 mutations in POL30, which encodes PCNA in Saccharomyces cerevisiae, specific to Exo1-independent MMR. The mutations identified affected amino acids at three distinct sites on the PCNA structure. Multiple mutant PCNA proteins had defects either in trimerization and Msh2-Msh6 binding or in activation of the Mlh1-Pms1 endonuclease that initiates excision during MMR. The latter class of mutations led to hyperaccumulation of repair intermediate Mlh1-Pms1 foci and were enhanced by an msh6 mutation that disrupted the Msh2-Msh6 interaction with PCNA. These results reveal a central role for PCNA in the Exo1-independent MMR pathway and suggest that Msh2-Msh6 localizes PCNA to repair sites after mispair recognition to activate the Mlh1-Pms1 endonuclease for initiating Exo1-dependent repair or for driving progressive excision in Exo1-independent repair.
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Affiliation(s)
- Eva M Goellner
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Catherine E Smith
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Christopher S Campbell
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Hans Hombauer
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Arshad Desai
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Christopher D Putnam
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA
| | - Richard D Kolodner
- Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Moores-UCSD Cancer Center, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Institute of Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
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11
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Campbell CS, Hombauer H, Srivatsan A, Bowen N, Gries K, Desai A, Putnam CD, Kolodner RD. Mlh2 is an accessory factor for DNA mismatch repair in Saccharomyces cerevisiae. PLoS Genet 2014; 10:e1004327. [PMID: 24811092 PMCID: PMC4014439 DOI: 10.1371/journal.pgen.1004327] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 03/10/2014] [Indexed: 12/30/2022] Open
Abstract
In Saccharomyces cerevisiae, the essential mismatch repair (MMR) endonuclease Mlh1-Pms1 forms foci promoted by Msh2-Msh6 or Msh2-Msh3 in response to mispaired bases. Here we analyzed the Mlh1-Mlh2 complex, whose role in MMR has been unclear. Mlh1-Mlh2 formed foci that often colocalized with and had a longer lifetime than Mlh1-Pms1 foci. Mlh1-Mlh2 foci were similar to Mlh1-Pms1 foci: they required mispair recognition by Msh2-Msh6, increased in response to increased mispairs or downstream defects in MMR, and formed after induction of DNA damage by phleomycin but not double-stranded breaks by I-SceI. Mlh1-Mlh2 could be recruited to mispair-containing DNA in vitro by either Msh2-Msh6 or Msh2-Msh3. Deletion of MLH2 caused a synergistic increase in mutation rate in combination with deletion of MSH6 or reduced expression of Pms1. Phylogenetic analysis demonstrated that the S. cerevisiae Mlh2 protein and the mammalian PMS1 protein are homologs. These results support a hypothesis that Mlh1-Mlh2 is a non-essential accessory factor that acts to enhance the activity of Mlh1-Pms1. Lynch syndrome (hereditary nonpolyposis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. In this syndrome, predisposition to cancer results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the human mismatch repair genes MLH1, MSH2, MSH6 or PMS2. In addition to these genes, various DNA replication factors and the excision factor EXO1 function in the repair of damaged DNA by the MMR pathway. In Saccharomyces cerevisiae, the MLH2 gene encodes a MutL homolog protein whose role in DNA mismatch repair has been unclear. Here, we used phylogenetic analysis to demonstrate that the S. cerevisiae Mlh2 protein and the mammalian Pms1 protein are homologs. A combination of genetics, biochemistry and imaging studies were used to demonstrate that the Mlh1-Mlh2 complex is recruited to mispair-containing DNA by the Msh2-Msh6 and Msh2-Msh3 mispair recognition complexes where it forms foci that colocalize with Mlh1-Pms1 foci (note that scPms1 is the homolog of hPms2) and augments the function of the Mlh1-Pms1 complex. Thus, this work establishes the Mlh1-Mlh2 complex as a non-essential accessory factor that functions in MMR.
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Affiliation(s)
- Christopher S. Campbell
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Hans Hombauer
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, Heidelberg, Germany
| | - Anjana Srivatsan
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Nikki Bowen
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Kerstin Gries
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, Heidelberg, Germany
| | - Arshad Desai
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Christopher D. Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
| | - Richard D. Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, California, United States of America
- * E-mail:
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12
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Rogacheva MV, Manhart CM, Chen C, Guarne A, Surtees J, Alani E. Mlh1-Mlh3, a meiotic crossover and DNA mismatch repair factor, is a Msh2-Msh3-stimulated endonuclease. J Biol Chem 2014; 289:5664-73. [PMID: 24403070 DOI: 10.1074/jbc.m113.534644] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Crossing over between homologous chromosomes is initiated in meiotic prophase in most sexually reproducing organisms by the appearance of programmed double strand breaks throughout the genome. In Saccharomyces cerevisiae the double-strand breaks are resected to form three prime single-strand tails that primarily invade complementary sequences in unbroken homologs. These invasion intermediates are converted into double Holliday junctions and then resolved into crossovers that facilitate homolog segregation during Meiosis I. Work in yeast suggests that Msh4-Msh5 stabilizes invasion intermediates and double Holliday junctions, which are resolved into crossovers in steps requiring Sgs1 helicase, Exo1, and a putative endonuclease activity encoded by the DNA mismatch repair factor Mlh1-Mlh3. We purified Mlh1-Mlh3 and showed that it is a metal-dependent and Msh2-Msh3-stimulated endonuclease that makes single-strand breaks in supercoiled DNA. These observations support a direct role for an Mlh1-Mlh3 endonuclease activity in resolving recombination intermediates and in DNA mismatch repair.
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Affiliation(s)
- Maria V Rogacheva
- From the Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
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13
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Smith CE, Mendillo ML, Bowen N, Hombauer H, Campbell CS, Desai A, Putnam CD, Kolodner RD. Dominant mutations in S. cerevisiae PMS1 identify the Mlh1-Pms1 endonuclease active site and an exonuclease 1-independent mismatch repair pathway. PLoS Genet 2013; 9:e1003869. [PMID: 24204293 PMCID: PMC3814310 DOI: 10.1371/journal.pgen.1003869] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/25/2013] [Indexed: 12/28/2022] Open
Abstract
Lynch syndrome (hereditary nonpolypsis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. Predisposition to cancer in this syndrome results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2/scPMS1. To better understand the function of Mlh1-Pms1 in MMR, we used Saccharomyces cerevisiae to identify six pms1 mutations (pms1-G683E, pms1-C817R, pms1-C848S, pms1-H850R, pms1-H703A and pms1-E707A) that were weakly dominant in wild-type cells, which surprisingly caused a strong MMR defect when present on low copy plasmids in an exo1Δ mutant. Molecular modeling showed these mutations caused amino acid substitutions in the metal coordination pocket of the Pms1 endonuclease active site and biochemical studies showed that they inactivated the endonuclease activity. This model of Mlh1-Pms1 suggested that the Mlh1-FERC motif contributes to the endonuclease active site. Consistent with this, the mlh1-E767stp mutation caused both MMR and endonuclease defects similar to those caused by the dominant pms1 mutations whereas mutations affecting the predicted metal coordinating residue Mlh1-C769 had no effect. These studies establish that the Mlh1-Pms1 endonuclease is required for MMR in a previously uncharacterized Exo1-independent MMR pathway. Lynch syndrome (hereditary nonpolypsis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. Predisposition to cancer in this syndrome results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2/scPMS1. In addition to these genes, various DNA replication factors and the excision factor EXO1 function in the repair of damaged DNA by the MMR pathway. Although EXO1 is considered to be the major repair nuclease functioning in mismatch repair, the relatively low mutation rates caused by an exo1 deletion suggest otherwise. Here we used genetics, microscopy and protein biochemistry to analyze the model organism Saccharomyces cerevisiae to further characterize a poorly understood mismatch repair pathway that functions in the absence of EXO1 that is highly dependent on the Mlh1-Pms1 complex. Surprisingly, we found that the highly conserved metal binding site that is critical for the endonuclease activity of the Mlh1-Pms1 heterodimer is required for MMR in the absence of Exo1 to a much greater extent than in the presence of Exo1. Thus, this work establishes that there are at least two different polynucleotide excision pathways that function in MMR.
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Affiliation(s)
- Catherine E Smith
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, California, United States of America
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14
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Drost M, Koppejan H, de Wind N. Inactivation of DNA mismatch repair by variants of uncertain significance in the PMS2 gene. Hum Mutat 2013; 34:1477-80. [PMID: 24027009 DOI: 10.1002/humu.22426] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/05/2013] [Indexed: 01/14/2023]
Abstract
Lynch syndrome (LS) is a common cancer predisposition caused by an inactivating mutation in one of four DNA mismatch repair (MMR) genes. Frequently a variant of uncertain significance (VUS), rather than an obviously pathogenic mutation, is identified in one of these genes. The inability to define pathogenicity of such variants precludes targeted healthcare. Here, we have modified a cell-free assay to test VUS in the MMR gene PMS2 for functional activity. We have analyzed nearly all VUS in PMS2 found thus far and describe loss of MMR activity for five, suggesting the applicability of the assay for diagnosis of LS.
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Affiliation(s)
- Mark Drost
- Department of Toxicogenetics, Leiden University Medical Center, Leiden, The Netherlands
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15
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Borràs E, Pineda M, Cadiñanos J, Del Valle J, Brieger A, Hinrichsen I, Cabanillas R, Navarro M, Brunet J, Sanjuan X, Musulen E, van der Klift H, Lázaro C, Plotz G, Blanco I, Capellá G. Refining the role of PMS2 in Lynch syndrome: germline mutational analysis improved by comprehensive assessment of variants. J Med Genet 2013; 50:552-63. [PMID: 23709753 DOI: 10.1136/jmedgenet-2012-101511] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND AIM The majority of mismatch repair (MMR) gene mutations causing Lynch syndrome (LS) occur either in MLH1 or MSH2. However, the relative contribution of PMS2 is less well defined. The aim of this study was to evaluate the role of PMS2 in LS by assessing the pathogenicity of variants of unknown significance (VUS) detected in the mutational analysis of PMS2 in a series of Spanish patients. METHODS From a cohort of 202 LS suspected patients, 13 patients showing loss of PMS2 expression in tumours were screened for germline mutations in PMS2, using a long range PCR based strategy and multiplex ligation dependent probe amplification (MLPA). Pathogenicity assessment of PMS2 VUS was performed evaluating clinicopathological data, frequency in control population and in silico and in vitro analyses at the RNA and protein level. RESULTS Overall 25 different PMS2 DNA variants were detected. Fourteen were classified as polymorphisms. Nine variants were classified as pathogenic: seven alterations based on their molecular nature and two after demonstrating a functional defect (c.538-3C>G affected mRNA processing and c.137G>T impaired MMR activity). The c.1569C>G variant was classified as likely neutral while the c.384G>A remained as a VUS. We have also shown that the polymorphic variant c.59G>A is MMR proficient. CONCLUSIONS Pathogenic PMS2 mutations were detected in 69% of patients harbouring LS associated tumours with loss of PMS2 expression. In all, PMS2 mutations account for 6% of the LS cases identified. The comprehensive functional analysis shown here has been useful in the classification of PMS2 VUS and contributes to refining the role of PMS2 in LS.
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Affiliation(s)
- Ester Borràs
- Hereditary Cancer Program, Catalan Institute of Oncology, ICO-IDIBELL, Hospitalet de Llobregat, Barcelona, Spain
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16
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Structure of the MutLα C-terminal domain reveals how Mlh1 contributes to Pms1 endonuclease site. Nat Struct Mol Biol 2013; 20:461-8. [PMID: 23435383 DOI: 10.1038/nsmb.2511] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 01/04/2013] [Indexed: 01/30/2023]
Abstract
Mismatch-repair factors have a prominent role in surveying eukaryotic DNA-replication fidelity and in ensuring correct meiotic recombination. These functions depend on MutL-homolog heterodimers with Mlh1. In humans, MLH1 mutations underlie half of hereditary nonpolyposis colorectal cancers (HNPCCs). Here we report crystal structures of the MutLα (Mlh1-Pms1 heterodimer) C-terminal domain (CTD) from Saccharomyces cerevisiae, alone and in complex with fragments derived from Mlh1 partners. These structures reveal structural rearrangements and additional domains in MutLα as compared to the bacterial MutL counterparts and show that the strictly conserved C terminus of Mlh1 forms part of the Pms1 endonuclease site. The structures of the ternary complexes between MutLα(CTD) and Exo1 or Ntg2 fragments reveal the binding mode of the MIP-box motif shared by several Mlh1 partners. Finally, the structures provide a rationale for the deleterious impact of MLH1 mutations in HNPCCs.
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17
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Martín-López JV, Barrios Y, Medina-Arana V, Andújar M, Lee S, Gu L, Li GM, Rüschoff J, Salido E, Fishel R. The hMSH2(M688R) Lynch syndrome mutation may function as a dominant negative. Carcinogenesis 2012; 33:1647-54. [PMID: 22739024 DOI: 10.1093/carcin/bgs199] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The hMSH2(M688R) mismatch repair (MMR) gene mutation has been found in five large families from Tenerife, Spain, suggesting it is a Lynch syndrome or hereditary non-polyposis colorectal cancer (LS/HNPCC) founder mutation. In addition to classical LS/HNPCC tumors, these families present with a high incidence of central nervous system (CNS) tumors normally associated with Turcot or constitutional mismatch repair deficiency (CMMR-D) syndromes. Turcot and CMMR-D mutations may be biallelic, knocking out both copies of the MMR gene. The hMSH2(M688R) mutation is located in the ATP hydrolysis (ATPase) domain. We show that the hMSH2(M688R)-hMSH6 heterodimer binds to mismatched nucleotides but lacks normal ATP functions and inhibits MMR in vitro when mixed with the wild-type (WT) heterodimer. Another alteration that has been associated with LS/HNPCC, hMSH2(M688I)-hMSH6, displays no identifiable differences with the WT heterodimer. Interestingly, some extracolonic tumors from hMSH2(M688R) carriers may express hMSH2-hMSH6, yet display microsatellite instability (MSI). The functional analysis along with variability in tumor expression and the high incidence of CNS tumors suggests that hMSH2(M688R) may act as a dominant negative in some tissues, while the hMSH2(M688I) is most likely a benign polymorphism.
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Affiliation(s)
- Juana V Martín-López
- Unidad de Investigación Mixta HUC-ULL, Facultad de Medicina, Universidad de La Laguna, La Laguna, Santa Cruz de Tenerife, 38002, Spain
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18
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Hombauer H, Campbell CS, Smith CE, Desai A, Kolodner RD. Visualization of eukaryotic DNA mismatch repair reveals distinct recognition and repair intermediates. Cell 2012; 147:1040-53. [PMID: 22118461 DOI: 10.1016/j.cell.2011.10.025] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 07/22/2011] [Accepted: 10/07/2011] [Indexed: 11/17/2022]
Abstract
DNA mismatch repair (MMR) increases replication fidelity by eliminating mispaired bases resulting from replication errors. In Saccharomyces cerevisiae, mispairs are primarily detected by the Msh2-Msh6 complex and corrected following recruitment of the Mlh1-Pms1 complex. Here, we visualized functional fluorescent versions of Msh2-Msh6 and Mlh1-Pms1 in living cells. We found that the Msh2-Msh6 complex is an S phase component of replication centers independent of mispaired bases; this localized pool accounted for 10%-15% of MMR in wild-type cells but was essential for MMR in the absence of Exo1. Unexpectedly, Mlh1-Pms1 formed nuclear foci that, although dependent on Msh2-Msh6 for formation, rarely colocalized with Msh2-Msh6 replication-associated foci. Mlh1-Pms1 foci increased when the number of mispaired bases was increased; in contrast, Msh2-Msh6 foci were unaffected. These findings suggest the presence of replication machinery-coupled and -independent pathways for mispair recognition by Msh2-Msh6, which direct formation of superstoichiometric Mlh1-Pms1 foci that represent sites of active MMR.
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Affiliation(s)
- Hans Hombauer
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA
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19
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Correa EME, Martina MA, De Tullio L, Argaraña CE, Barra JL. Some amino acids of the Pseudomonas aeruginosa MutL D(Q/M)HA(X)(2)E(X)(4)E conserved motif are essential for the in vivo function of the protein but not for the in vitro endonuclease activity. DNA Repair (Amst) 2011; 10:1106-13. [PMID: 21889424 DOI: 10.1016/j.dnarep.2011.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 08/05/2011] [Accepted: 08/10/2011] [Indexed: 11/25/2022]
Abstract
Human and Saccharomyces cerevisiae MutLα, and some bacterial MutL proteins, possess a metal ion-dependent endonuclease activity which is important for the in vivo function of these proteins. Conserved amino acids of the C-terminal region of human PMS2, S. cerevisiae PMS1 and of some bacterial MutL proteins have been implicated in the metal-binding/endonuclease activity. However, the contribution of individual amino acids to these activities has not yet been fully elucidated. In this work we show that Pseudomonas aeruginosa MutL protein possess an in vitro metal ion-dependent endonuclease activity. In agreement with previous published results, we observed that mutation of the aspartic acid, the first histidine or the first glutamic acid of the conserved C-terminal DMHAAHERITYE region results in nonfunctional in vivo proteins. We also determined that the arginine residue is essential for the in vivo function of this protein. However, we unexpectedly observed that although the first glutamic acid mutant derivative is not functional in vivo, its in vitro endonuclease activity is even higher than that of the wild-type protein.
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Affiliation(s)
- Elisa M E Correa
- Centro de Investigaciones en Química Biológica de Córdoba, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
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20
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Johnson JR, Erdeniz N, Nguyen M, Dudley S, Liskay RM. Conservation of functional asymmetry in the mammalian MutLα ATPase. DNA Repair (Amst) 2011; 9:1209-13. [PMID: 20864418 DOI: 10.1016/j.dnarep.2010.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 08/14/2010] [Indexed: 11/30/2022]
Abstract
The DNA mismatch repair (MMR) protein dimer MutLα is comprised of the MutL homologues MLH1 and PMS2, which each belong to the family of GHL ATPases. These ATPases undergo functionally important conformational changes, including dimerization of the NH₂-termini associated with ATP binding and hydrolysis. Previous studies in yeast and biochemical studies with the mammalian proteins established the importance of the MutLα ATPase for overall MMR function. Additionally, the studies in yeast demonstrated a functional asymmetry between the contributions of the Mlh1 and Pms1 ATPase domains to MMR that was not reflected in the biochemical studies. We investigated the effect of mutating the highly conserved ATP hydrolysis and Mg²(+) binding residues of MLH1 and PMS2 in mammalian cell lines. Amino acid substitutions in MLH1 intended to impact either ATP binding or hydrolysis disabled MMR, as measured by instability at microsatellite sequences, to an extent similar to MLH1-null mutation. Furthermore, cells expressing these MLH1 mutations exhibited resistance to the MMR-dependent cytotoxic effect of 6-thioguanine (6-TG). In contrast, ATP hydrolysis and binding mutants of PMS2 displayed no measurable increase in microsatellite instability or resistance to 6-TG. Our findings suggest that, in vivo, the integrity of the MLH1 ATPase domain is more critical than the PMS2 ATPase domain for normal MMR functions. These in vivo results are in contrast to results obtained previously in vitro that showed no functional asymmetry within the MutLα ATPase, highlighting the differences between in vivo and in vitro systems.
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21
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Namadurai S, Jain D, Kulkarni DS, Tabib CR, Friedhoff P, Rao DN, Nair DT. The C-terminal domain of the MutL homolog from Neisseria gonorrhoeae forms an inverted homodimer. PLoS One 2010; 5:e13726. [PMID: 21060849 PMCID: PMC2965676 DOI: 10.1371/journal.pone.0013726] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 09/23/2010] [Indexed: 01/07/2023] Open
Abstract
The mismatch repair (MMR) pathway serves to maintain the integrity of the genome by removing mispaired bases from the newly synthesized strand. In E. coli, MutS, MutL and MutH coordinate to discriminate the daughter strand through a mechanism involving lack of methylation on the new strand. This facilitates the creation of a nick by MutH in the daughter strand to initiate mismatch repair. Many bacteria and eukaryotes, including humans, do not possess a homolog of MutH. Although the exact strategy for strand discrimination in these organisms is yet to be ascertained, the required nicking endonuclease activity is resident in the C-terminal domain of MutL. This activity is dependent on the integrity of a conserved metal binding motif. Unlike their eukaryotic counterparts, MutL in bacteria like Neisseria exist in the form of a homodimer. Even though this homodimer would possess two active sites, it still acts a nicking endonuclease. Here, we present the crystal structure of the C-terminal domain (CTD) of the MutL homolog of Neisseria gonorrhoeae (NgoL) determined to a resolution of 2.4 Å. The structure shows that the metal binding motif exists in a helical configuration and that four of the six conserved motifs in the MutL family, including the metal binding site, localize together to form a composite active site. NgoL-CTD exists in the form of an elongated inverted homodimer stabilized by a hydrophobic interface rich in leucines. The inverted arrangement places the two composite active sites in each subunit on opposite lateral sides of the homodimer. Such an arrangement raises the possibility that one of the active sites is occluded due to interaction of NgoL with other protein factors involved in MMR. The presentation of only one active site to substrate DNA will ensure that nicking of only one strand occurs to prevent inadvertent and deleterious double stranded cleavage.
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Affiliation(s)
| | - Deepti Jain
- Laboratory 4, National Centre for Biological Sciences, Bangalore, India
| | | | - Chaitanya R. Tabib
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Peter Friedhoff
- Institut für Biochemie (FB 08), Justus-Liebig-Universität, Giessen, Germany
| | - Desirazu N. Rao
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Deepak T. Nair
- Laboratory 4, National Centre for Biological Sciences, Bangalore, India
- * E-mail:
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22
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PMS2 endonuclease activity has distinct biological functions and is essential for genome maintenance. Proc Natl Acad Sci U S A 2010; 107:13384-9. [PMID: 20624957 DOI: 10.1073/pnas.1008589107] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The DNA mismatch repair protein PMS2 was recently found to encode a novel endonuclease activity. To determine the biological functions of this activity in mammals, we generated endonuclease-deficient Pms2E702K knock-in mice. Pms2EK/EK mice displayed increased genomic mutation rates and a strong cancer predisposition. In addition, class switch recombination, but not somatic hypermutation, was impaired in Pms2EK/EK B cells, indicating a specific role in Ig diversity. In contrast to Pms2-/- mice, Pms2EK/EK male mice were fertile, indicating that this activity is dispensable in spermatogenesis. Therefore, the PMS2 endonuclease activity has distinct biological functions and is essential for genome maintenance and tumor suppression.
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23
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Functional analysis of human mismatch repair gene mutations identifies weak alleles and polymorphisms capable of polygenic interactions. Proc Natl Acad Sci U S A 2010; 107:5070-5. [PMID: 20176959 DOI: 10.1073/pnas.1000798107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Many of the mutations reported as potentially causing Lynch syndrome are missense mutations in human mismatch repair (MMR) genes. Here, we used a Saccharomyces cerevisiae-based system to study polymorphisms and suspected missense mutations in human MMR genes by modeling them at the appropriate S. cerevisiae chromosomal locus and determining their effect on mutation rates. We identified a number of weak alleles of MMR genes and MMR gene polymorphisms that are capable of interacting with other weak alleles of MMR genes to produce strong polygenic MMR defects. We also identified a number of alleles of MSH2 that act as if they inactivate the Msh2-Msh3 mispair recognition complex thus causing weak MMR defects that interact with an msh6Delta mutation to result in complete MMR defects. These results indicate that weak MMR gene alleles capable of polygenic interactions with other MMR gene alleles may be relatively common.
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24
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The C-terminal domain is sufficient for endonuclease activity of Neisseria gonorrhoeae MutL. Biochem J 2009; 423:265-77. [PMID: 19656086 DOI: 10.1042/bj20090626] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The mutL gene of Neisseria gonorrhoeae has been cloned and the gene product purified. We have found that the homodimeric N. gonorrhoeae MutL (NgoL) protein displays an endonuclease activity that incises covalently closed circular DNA in the presence of Mn(2+), Mg(2+) or Ca(2+) ions, unlike human MutLalpha which shows endonuclease activity only in the presence of Mn(2+). We report in the present paper that the C-terminal domain of N. gonorrhoeae MutL (NgoL-CTD) consisting of amino acids 460-658 exhibits Mn(2+)-dependent endonuclease activity. Sedimentation velocity, sedimentation equilibrium and dynamic light scattering experiments show NgoL-CTD to be a dimer. The probable endonucleolytic active site is localized to a metal-binding motif, DMHAX2EX4E, and the nicking endonuclease activity is dependent on the integrity of this motif. By in vitro comparison of wild-type and a mutant NgoL-CTD protein, we show that the latter protein exhibits highly reduced endonuclease activity. We therefore suggest that the mode of excision initiation in DNA mismatch repair may be different in organisms that lack MutH protein, but have MutL proteins that harbour the D[M/Q]HAX2EX4E motif.
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25
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Hsieh P, Yamane K. DNA mismatch repair: molecular mechanism, cancer, and ageing. Mech Ageing Dev 2008; 129:391-407. [PMID: 18406444 PMCID: PMC2574955 DOI: 10.1016/j.mad.2008.02.012] [Citation(s) in RCA: 291] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2007] [Revised: 02/22/2008] [Accepted: 02/28/2008] [Indexed: 02/09/2023]
Abstract
DNA mismatch repair (MMR) proteins are ubiquitous players in a diverse array of important cellular functions. In its role in post-replication repair, MMR safeguards the genome correcting base mispairs arising as a result of replication errors. Loss of MMR results in greatly increased rates of spontaneous mutation in organisms ranging from bacteria to humans. Mutations in MMR genes cause hereditary nonpolyposis colorectal cancer, and loss of MMR is associated with a significant fraction of sporadic cancers. Given its prominence in mutation avoidance and its ability to target a range of DNA lesions, MMR has been under investigation in studies of ageing mechanisms. This review summarizes what is known about the molecular details of the MMR pathway and the role of MMR proteins in cancer susceptibility and ageing.
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Affiliation(s)
- Peggy Hsieh
- Genetics & Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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26
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Kosinski J, Plotz G, Guarné A, Bujnicki JM, Friedhoff P. The PMS2 subunit of human MutLalpha contains a metal ion binding domain of the iron-dependent repressor protein family. J Mol Biol 2008; 382:610-27. [PMID: 18619468 DOI: 10.1016/j.jmb.2008.06.056] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 06/13/2008] [Accepted: 06/23/2008] [Indexed: 12/22/2022]
Abstract
DNA mismatch repair (MMR) is responsible for correcting replication errors. MutLalpha, one of the main players in MMR, has been recently shown to harbor an endonuclease/metal-binding activity, which is important for its function in vivo. This endonuclease activity has been confined to the C-terminal domain of the hPMS2 subunit of the MutLalpha heterodimer. In this work, we identify a striking sequence-structure similarity of hPMS2 to the metal-binding/dimerization domain of the iron-dependent repressor protein family and present a structural model of the metal-binding domain of MutLalpha. According to our model, this domain of MutLalpha comprises at least three highly conserved sequence motifs, which are also present in most MutL homologs from bacteria that do not rely on the endonuclease activity of MutH for strand discrimination. Furthermore, based on our structural model, we predict that MutLalpha is a zinc ion binding protein and confirm this prediction by way of biochemical analysis of zinc ion binding using the full-length and C-terminal domain of MutLalpha. Finally, we demonstrate that the conserved residues of the metal ion binding domain are crucial for MMR activity of MutLalpha in vitro.
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Affiliation(s)
- Jan Kosinski
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
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27
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Nishant KT, Plys AJ, Alani E. A mutation in the putative MLH3 endonuclease domain confers a defect in both mismatch repair and meiosis in Saccharomyces cerevisiae. Genetics 2008; 179:747-755. [PMID: 18505871 PMCID: PMC2429871 DOI: 10.1534/genetics.108.086645] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 03/20/2008] [Indexed: 07/26/2023] Open
Abstract
Interference-dependent crossing over in yeast and mammalian meioses involves the mismatch repair protein homologs MSH4-MSH5 and MLH1-MLH3. The MLH3 protein contains a highly conserved metal-binding motif DQHA(X)(2)E(X)(4)E that is found in a subset of MLH proteins predicted to have endonuclease activities (Kadyrov et al. 2006). Mutations within this motif in human PMS2 and Saccharomyces cerevisiae PMS1 disrupted the endonuclease and mismatch repair activities of MLH1-PMS2 and MLH1-PMS1, respectively (Kadyrov et al. 2006, 2007; Erdeniz et al. 2007). As a first step in determining whether such an activity is required during meiosis, we made mutations in the MLH3 putative endonuclease domain motif (-D523N, -E529K) and found that single and double mutations conferred mlh3-null-like defects with respect to meiotic spore viability and crossing over. Yeast two-hybrid and chromatography analyses showed that the interaction between MLH1 and mlh3-D523N was maintained, suggesting that the mlh3-D523N mutation did not disrupt the stability of MLH3. The mlh3-D523N mutant also displayed a mutator phenotype in vegetative growth that was similar to mlh3Delta. Overexpression of this allele conferred a dominant-negative phenotype with respect to mismatch repair. These studies suggest that the putative endonuclease domain of MLH3 plays an important role in facilitating mismatch repair and meiotic crossing over.
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Affiliation(s)
- K T Nishant
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA
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Kadyrov FA, Holmes SF, Arana ME, Lukianova OA, O'Donnell M, Kunkel TA, Modrich P. Saccharomyces cerevisiae MutLalpha is a mismatch repair endonuclease. J Biol Chem 2007; 282:37181-90. [PMID: 17951253 PMCID: PMC2302834 DOI: 10.1074/jbc.m707617200] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
MutL homologs are crucial for mismatch repair and genetic stability, but their function is not well understood. Human MutLalpha (MLH1-PMS2 heterodimer) harbors a latent endonuclease that is dependent on the integrity of a PMS2 DQHA(X)2E(X)4E motif (Kadyrov, F. A., Dzantiev, L., Constantin, N., and Modrich, P. (2006) Cell 126, 297-308). This sequence element is conserved in many MutL homologs, including the PMS1 subunit of Saccharomyces cerevisiae MutLalpha, but is absent in MutL proteins from bacteria like Escherichia coli that rely on d(GATC) methylation for strand directionality. We show that yeast MutLalpha is a strand-directed endonuclease that incises DNA in a reaction that depends on a mismatch, yMutSalpha, yRFC, yPCNA, ATP, and a pre-existing strand break, whereas E. coli MutL is not. Amino acid substitution within the PMS1 DQHA(X)2E(X)4E motif abolishes yMutLalpha endonuclease activity in vitro and confers strong genetic instability in vivo, but does not affect yMutLalpha ATPase activity or the ability of the protein to support assembly of the yMutLalpha.yMutSalpha.heteroduplex ternary complex. The loaded form of yPCNA may play an important effector role in directing yMutLalpha incision to the discontinuous strand of a nicked heteroduplex.
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Affiliation(s)
- Farid A Kadyrov
- Department of Biochemistry and Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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Erdeniz N, Nguyen M, Deschênes SM, Liskay RM. Mutations affecting a putative MutLalpha endonuclease motif impact multiple mismatch repair functions. DNA Repair (Amst) 2007; 6:1463-70. [PMID: 17567544 PMCID: PMC2366940 DOI: 10.1016/j.dnarep.2007.04.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 04/16/2007] [Indexed: 12/11/2022]
Abstract
Mutations in DNA mismatch repair (MMR) lead to increased mutation rates and higher recombination between similar, but not identical sequences, as well as resistance to certain DNA methylating agents. Recently, a component of human MMR machinery, MutLalpha, has been shown to display a latent endonuclease activity. The endonuclease active site appears to include a conserved motif, DQHA(X)(2)E(X)(4)E, within the COOH-terminus of human PMS2. Substitution of the glutamic acid residue (E705) abolished the endonuclease activity and mismatch-dependent excision in vitro. Previously, we showed that the PMS2-E705K mutation and the corresponding mutation in Saccharomyces cerevisiae were both recessive loss of function alleles for mutation avoidance in vivo. Here, we show that mutations impacting this endonuclease motif also significantly affect MMR-dependent suppression of homeologous recombination in yeast and responses to S(n)1-type methylating agents in both yeast and mammalian cells. Thus, our in vivo results suggest that the endonuclease activity of MutLalpha is important not only in MMR-dependent mutation avoidance but also for recombination and damage response functions.
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Affiliation(s)
- Naz Erdeniz
- Department of Molecular and Medical Genetics, Oregon Health & Science University L103, 3181 SW, Sam Jackson Park Road, Portland, OR 97239-3098, United States
| | - Megan Nguyen
- Department of Molecular and Medical Genetics, Oregon Health & Science University L103, 3181 SW, Sam Jackson Park Road, Portland, OR 97239-3098, United States
| | - Suzanne M. Deschênes
- Department of Biology, Sacred Heart University, 5151 Park Ave., Fairfield, CT 06825, United States
| | - R. Michael Liskay
- Department of Molecular and Medical Genetics, Oregon Health & Science University L103, 3181 SW, Sam Jackson Park Road, Portland, OR 97239-3098, United States
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