1
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Sloan DB, Broz AK, Kuster SA, Muthye V, Peñafiel-Ayala A, Marron JR, Lavrov DV, Brieba LG. Expansion of the MutS Gene Family in Plants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.17.603841. [PMID: 39071318 PMCID: PMC11275761 DOI: 10.1101/2024.07.17.603841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The MutS gene family is distributed across the tree of life and is involved in recombination, DNA repair, and protein translation. Multiple evolutionary processes have expanded the set of MutS genes in plants relative to other eukaryotes. Here, we investigate the origins and functions of these plant-specific genes. Land plants, green algae, red algae, and glaucophytes share cyanobacterial-like MutS1 and MutS2 genes that presumably were gained via plastid endosymbiotic gene transfer. MutS1 was subsequently lost in some taxa, including seed plants, whereas MutS2 was duplicated in Viridiplantae (i.e., land plants and green algae) with widespread retention of both resulting paralogs. Viridiplantae also have two anciently duplicated copies of the eukaryotic MSH6 gene (i.e., MSH6 and MSH7) and acquired MSH1 via horizontal gene transfer - potentially from a nucleocytovirus. Despite sharing the same name, "plant MSH1" is not directly related to the gene known as MSH1 in some fungi and animals, which may be an ancestral eukaryotic gene acquired via mitochondrial endosymbiosis and subsequently lost in most eukaryotic lineages. There has been substantial progress in understanding the functions of MSH1 and MSH6/MSH7 in plants, but the roles of the cyanobacterial-like MutS1 and MutS2 genes remain uncharacterized. Known functions of bacterial homologs and predicted protein structures, including fusions to diverse nuclease domains, provide hypotheses about potential molecular mechanisms. Because most plant-specific MutS proteins are targeted to the mitochondria and/or plastids, the expansion of this family appears to have played a large role in shaping plant organelle genetics.
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Affiliation(s)
- Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Shady A Kuster
- Department of Biology, Colorado State University, Fort Collins, CO, USA
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA
| | - Viraj Muthye
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Alejandro Peñafiel-Ayala
- Unidad de Genómica Avanzada, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Gto, México
| | - Jennifer R Marron
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Dennis V Lavrov
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
| | - Luis G Brieba
- Unidad de Genómica Avanzada, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Gto, México
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2
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Pal S, Yuvaraj R, Krishnan H, Venkatraman B, Abraham J, Gopinathan A. Unraveling radiation resistance strategies in two bacterial strains from the high background radiation area of Chavara-Neendakara: A comprehensive whole genome analysis. PLoS One 2024; 19:e0304810. [PMID: 38857267 PMCID: PMC11164402 DOI: 10.1371/journal.pone.0304810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 05/18/2024] [Indexed: 06/12/2024] Open
Abstract
This paper reports the results of gamma irradiation experiments and whole genome sequencing (WGS) performed on vegetative cells of two radiation resistant bacterial strains, Metabacillus halosaccharovorans (VITHBRA001) and Bacillus paralicheniformis (VITHBRA024) (D10 values 2.32 kGy and 1.42 kGy, respectively), inhabiting the top-ranking high background radiation area (HBRA) of Chavara-Neendakara placer deposit (Kerala, India). The present investigation has been carried out in the context that information on strategies of bacteria having mid-range resistance for gamma radiation is inadequate. WGS, annotation, COG and KEGG analyses and manual curation of genes helped us address the possible pathways involved in the major domains of radiation resistance, involving recombination repair, base excision repair, nucleotide excision repair and mismatch repair, and the antioxidant genes, which the candidate could activate to survive under ionizing radiation. Additionally, with the help of these data, we could compare the candidate strains with that of the extremely radiation resistant model bacterium Deinococccus radiodurans, so as to find the commonalities existing in their strategies of resistance on the one hand, and also the rationale behind the difference in D10, on the other. Genomic analysis of VITHBRA001 and VITHBRA024 has further helped us ascertain the difference in capability of radiation resistance between the two strains. Significantly, the genes such as uvsE (NER), frnE (protein protection), ppk1 and ppx (non-enzymatic metabolite production) and those for carotenoid biosynthesis, are endogenous to VITHBRA001, but absent in VITHBRA024, which could explain the former's better radiation resistance. Further, this is the first-time study performed on any bacterial population inhabiting an HBRA. This study also brings forward the two species whose radiation resistance has not been reported thus far, and add to the knowledge on radiation resistant capabilities of the phylum Firmicutes which are abundantly observed in extreme environment.
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Affiliation(s)
- Sowptika Pal
- Molecular Endocrinology Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Ramani Yuvaraj
- Radiological and Environmental Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India
| | - Hari Krishnan
- Radiological and Environmental Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India
| | - Balasubramanian Venkatraman
- Radiological and Environmental Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu, India
| | - Jayanthi Abraham
- Microbial Biotechnology Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Anilkumar Gopinathan
- Molecular Endocrinology Laboratory, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
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3
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Fukui K, Inoue M, Murakawa T, Baba S, Kumasaka T, Yano T. Structural and functional insights into the mechanism by which MutS2 recognizes a DNA junction. Structure 2022; 30:973-982.e4. [DOI: 10.1016/j.str.2022.03.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/11/2022] [Accepted: 03/23/2022] [Indexed: 10/18/2022]
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4
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Wang J, Zhu J, Wang C, Zhou G, Yu X, Fan H, An R, Komiyama M, Liang X. Thermus thermophilus DNA Ligase Connects Two Fragments Having Exceptionally Short Complementary Termini at High Temperatures. Biochemistry 2020; 59:400-406. [PMID: 31887028 DOI: 10.1021/acs.biochem.9b00866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thermus thermophilus DNA ligase (Tth DNA ligase) is widely employed for cloning, enzymatic synthesis, and molecular diagnostics at high temperatures (e.g., 65 °C). It has been long believed that the complementary ends must be very long (e.g., >30 bp) to place two DNA fragments nearby for the ligation. In the current study, the length of the complementary portion was systematically varied, and the ligation efficiency was evaluated using the high resolution melting (HRM) method. Unexpectedly, very short oligonucleotides (7-10 nt) were successfully ligated on the complementary overhang attached to a dsDNA at 70 °C. Furthermore, sticky ends with the overhang of only 4 nt long, available after scission with many restriction enzymes, were also efficiently ligated at 45-70 °C. The ligation yield for the 6-nt-long sticky ends was as high as 80%. It was concluded that Tth DNA ligase can be used as a unique tool for DNA manipulation that cannot be otherwise easily accomplished.
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Affiliation(s)
- Jing Wang
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China.,CAS Key laboratory of Marine Ecology and Environmental Sciences , Institute of Oceanology, Chinese Academy of Sciences , Qingdao 266071 , China
| | - Jianming Zhu
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Chenru Wang
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Guangqing Zhou
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Xin Yu
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Huijun Fan
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Ran An
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China.,Laboratory for Marine Drugs and Bioproducts , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266003 , China
| | - Makoto Komiyama
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Xingguo Liang
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China.,Laboratory for Marine Drugs and Bioproducts , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266003 , China
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5
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Zhang Y, Lu C. The Enigmatic Roles of PPR-SMR Proteins in Plants. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1900361. [PMID: 31380188 PMCID: PMC6662315 DOI: 10.1002/advs.201900361] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/03/2019] [Indexed: 05/21/2023]
Abstract
The pentatricopeptide repeat (PPR) protein family, with more than 400 members, is one of the largest and most diverse protein families in land plants. A small subset of PPR proteins contain a C-terminal small MutS-related (SMR) domain. Although there are relatively few PPR-SMR proteins, they play essential roles in embryo development, chloroplast biogenesis and gene expression, and plastid-to-nucleus retrograde signaling. Here, recent advances in understanding the roles of PPR-SMR proteins and the SMR domain based on a combination of genetic, biochemical, and physiological analyses are described. In addition, the potential of the PPR-SMR protein SOT1 to serve as a tool for RNA manipulation is highlighted.
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Affiliation(s)
- Yi Zhang
- State Key Laboratory of Crop BiologyCollege of Life SciencesShandong Agricultural UniversityTaianShandong271018P. R. China
| | - Congming Lu
- State Key Laboratory of Crop BiologyCollege of Life SciencesShandong Agricultural UniversityTaianShandong271018P. R. China
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6
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Ohshita K, Fukui K, Sato M, Morisawa T, Hakumai Y, Morono Y, Inagaki F, Yano T, Ashiuchi M, Wakamatsu T. Archaeal MutS5 tightly binds to Holliday junction similarly to eukaryotic MutSγ. FEBS J 2017; 284:3470-3483. [PMID: 28834211 DOI: 10.1111/febs.14204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/28/2017] [Accepted: 08/17/2017] [Indexed: 01/15/2023]
Abstract
Archaeal DNA recombination mechanism and the related proteins are similar to those in eukaryotes. However, no functional homolog of eukaryotic MutSγ, which recognizes Holliday junction to promote homologous recombination, has been identified in archaea. Hence, the whole molecular mechanism of archaeal homologous recombination has not yet been revealed. In this study, to identify the archaeal functional homolog of MutSγ, we focused on a functionally uncharacterized MutS homolog, MutS5, from a hyperthermophilic archaeon Pyrococcus horikoshii (phMutS5). Archaeal MutS5 has a Walker ATPase motif-containing amino acid sequence that shows similarity to the ATPase domain of MutSγ. It is known that the ATPase domain of MutS homologs is also a dimerization domain. Chemical cross-linking revealed that purified phMutS5 has an ability to dimerize in solution. phMutS5 bound to Holliday junction with a higher affinity than to other branched and linear DNAs, which resembles the DNA-binding specificities of MutSγ and bacterial MutS2, a Holliday junction-resolving MutS homolog. However, phMutS5 has no nuclease activity against branched DNA unlike MutS2. The ATPase activity of phMutS5 was significantly stimulated by the presence of Holliday junction similarly to MutSγ. Furthermore, site-directed mutagenesis revealed that the ATPase activity is dependent on the Walker ATPase motif of the protein. These results suggest that archaeal MutS5 should stabilize the Holliday junction and play a role in homologous recombination, which is analogous to the function of eukaryotic MutSγ.
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Affiliation(s)
- Koki Ohshita
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Japan
| | - Kenji Fukui
- Department of Biochemistry, Osaka Medical College, Takatsuki, Japan
| | - Mizuki Sato
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Japan
| | - Takashi Morisawa
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Japan
| | - Yuichi Hakumai
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Japan
| | - Yuki Morono
- Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Japan.,Geobio-Engineering and Technology Group, Submarine Resources Research Project, JAMSTEC, Nankoku, Japan
| | - Fumio Inagaki
- Geomicrobiology Group, Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Japan.,Geobio-Engineering and Technology Group, Submarine Resources Research Project, JAMSTEC, Nankoku, Japan.,Research and Development Center for Ocean Drilling Science, Yokohama, Japan
| | - Takato Yano
- Department of Biochemistry, Osaka Medical College, Takatsuki, Japan
| | - Makoto Ashiuchi
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Japan
| | - Taisuke Wakamatsu
- Agricultural Science, Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Japan
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7
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Molecular basis for the functions of a bacterial MutS2 in DNA repair and recombination. DNA Repair (Amst) 2017; 57:161-170. [PMID: 28800560 DOI: 10.1016/j.dnarep.2017.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 06/08/2017] [Accepted: 07/11/2017] [Indexed: 02/06/2023]
Abstract
Bacterial MutS2 proteins, consisting of functional domains for ATPase, DNA-binding, and nuclease activities, play roles in DNA recombination and repair. Here we observe a mechanism for generating MutS2 expression diversity in the human pathogen Helicobacter pylori, and identify a unique MutS2 domain responsible for specific DNA-binding. H. pylori strains differ in mutS2 expression due to variations in the DNA upstream sequence containing short sequence repeats. Based on Western blots, mutS2 in some strains appears to be co-translated with the upstream gene, but in other strains (e.g. UA948) such translational coupling does not occur. Accordingly, strain UA948 had phenotypes similar to its ΔmutS2 derivative, whereas expression of MutS2 at a separate locus in UA948 (the genetically complemented strain) displayed a lower mutation rate and lower transformation frequency than did ΔmutS2. A series of truncated HpMutS2 proteins were purified and tested for their specific abilities to bind 8-oxoG-containing DNA (GO:C) and Holiday Junction structures (HJ). The specific DNA binding domain was localized to an area adjacent to the Smr nuclease domain, and it encompasses 30-amino-acid-residues containing a "KPPKNKFKPPK" motif. Gel shift assays and competition assays supported that a truncated version of HpMutS2-C12 (∼12kDa protein containing the specific DNA-binding domain) has much greater capacity to bind to HJ or GO:C DNA than to normal double stranded DNA. By studying the in vivo roles of the separate domains of HpMutS2, we observed that the truncated versions were unable to complement the ΔmutS2 strain, suggesting the requirement for coordinated function of all the domains in vivo.
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8
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Burby PE, Simmons LA. MutS2 Promotes Homologous Recombination in Bacillus subtilis. J Bacteriol 2017; 199:e00682-16. [PMID: 27799325 PMCID: PMC5198493 DOI: 10.1128/jb.00682-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 10/21/2016] [Indexed: 02/07/2023] Open
Abstract
Bacterial MutS proteins are subdivided into two families, MutS1 and MutS2. MutS1 family members recognize DNA replication errors during their participation in the well-characterized mismatch repair (MMR) pathway. In contrast to the well-described function of MutS1, the function of MutS2 in bacteria has remained less clear. In Helicobacter pylori and Thermus thermophilus, MutS2 has been shown to suppress homologous recombination. The role of MutS2 is unknown in the Gram-positive bacterium Bacillus subtilis In this work, we investigated the contribution of MutS2 to maintaining genome integrity in B. subtilis We found that deletion of mutS2 renders B. subtilis sensitive to the natural antibiotic mitomycin C (MMC), which requires homologous recombination for repair. We demonstrate that the C-terminal small MutS-related (Smr) domain is necessary but not sufficient for tolerance to MMC. Further, we developed a CRISPR/Cas9 genome editing system to test if the inducible prophage PBSX was the underlying cause of the observed MMC sensitivity. Genetic analysis revealed that MMC sensitivity was dependent on recombination and not on nucleotide excision repair or a symptom of prophage PBSX replication and cell lysis. We found that deletion of mutS2 resulted in decreased transformation efficiency using both plasmid and chromosomal DNA. Further, deletion of mutS2 in a strain lacking the Holliday junction endonuclease gene recU resulted in increased MMC sensitivity and decreased transformation efficiency, suggesting that MutS2 could function redundantly with RecU. Together, our results support a model where B. subtilis MutS2 helps to promote homologous recombination, demonstrating a new function for bacterial MutS2. IMPORTANCE Cells contain pathways that promote or inhibit recombination. MutS2 homologs are Smr-endonuclease domain-containing proteins that have been shown to function in antirecombination in some bacteria. We present evidence that B. subtilis MutS2 promotes recombination, providing a new function for MutS2. We found that cells lacking mutS2 are sensitive to DNA damage that requires homologous recombination for repair and have reduced transformation efficiency. Further analysis indicates that the C-terminal Smr domain requires the N-terminal portion of MutS2 for function in vivo Moreover, we show that a mutS2 deletion is additive with a recU deletion, suggesting that these proteins have a redundant function in homologous recombination. Together, our study shows that MutS2 proteins have adapted different functions that impact recombination.
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Affiliation(s)
- Peter E Burby
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lyle A Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
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9
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Damke PP, Dhanaraju R, Marsin S, Radicella JP, Rao DN. The nuclease activities of both the Smr domain and an additional LDLK motif are required for an efficient anti-recombination function of Helicobacter pylori MutS2. Mol Microbiol 2015; 96:1240-56. [PMID: 25800579 DOI: 10.1111/mmi.13003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2015] [Indexed: 12/23/2022]
Abstract
Helicobacter pylori, a human pathogen, is a naturally and constitutively competent bacteria, displaying a high rate of intergenomic recombination. While recombination events are essential for evolution and adaptation of H. pylori to dynamic gastric niches and new hosts, such events should be regulated tightly to maintain genomic integrity. Here, we analyze the role of the nuclease activity of MutS2, a protein that limits recombination during transformation in H. pylori. In previously studied MutS2 proteins, the C-terminal Smr domain was mapped as the region responsible for its nuclease activity. We report here that deletion of Smr domain does not completely abolish the nuclease activity of HpMutS2. Using bioinformatics analysis and mutagenesis, we identified an additional and novel nuclease motif (LDLK) at the N-terminus of HpMutS2 unique to Helicobacter and related ε-proteobacterial species. A single point mutation (D30A) in the LDLK motif and the deletion of Smr domain resulted in ∼ 5-10-fold loss of DNA cleavage ability of HpMutS2. Interestingly, the mutant forms of HpMutS2 wherein the LDLK motif was mutated or the Smr domain was deleted were unable to complement the hyper-recombination phenotype of a mutS2(-) strain, suggesting that both nuclease sites are indispensable for an efficient anti-recombinase activity of HpMutS2.
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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
- Institute of Cellular and Molecular Radiobiology, CEA, Fontenay-aux-Roses, France.,INSERM UMR967, Fontenay-aux-Roses, France.,Universités Paris Diderot et Paris Sud, Fontenay-aux-Roses, France
| | - Juan Pablo Radicella
- Institute of Cellular and Molecular Radiobiology, CEA, 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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10
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Zhang H, Xu Q, Lu M, Xu X, Wang Y, Wang L, Zhao Y, Hua Y. Structural and functional studies of MutS2 from Deinococcus radiodurans. DNA Repair (Amst) 2014; 21:111-9. [DOI: 10.1016/j.dnarep.2014.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 04/18/2014] [Accepted: 04/20/2014] [Indexed: 01/13/2023]
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11
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Jeong E, Jo H, Kim TG, Ban C. Characterization of multi-functional properties and conformational analysis of MutS2 from Thermotoga maritima MSB8. PLoS One 2012; 7:e34529. [PMID: 22545085 PMCID: PMC3335848 DOI: 10.1371/journal.pone.0034529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/01/2012] [Indexed: 11/18/2022] Open
Abstract
The MutS2 homologues have received attention because of their unusual activities that differ from those of MutS. In this work, we report on the functional characteristics and conformational diversities of Thermotoga maritima MutS2 (TmMutS2). Various biochemical features of the protein were demonstrated via diverse techniques such as scanning probe microscopy (SPM), ATPase assays, analytical ultracentrifugation, DNA binding assays, size chromatography, and limited proteolytic analysis. Dimeric TmMutS2 showed the temperature-dependent ATPase activity. The non-specific nicking endonuclease activities of TmMutS2 were inactivated in the presence of nonhydrolytic ATP (ADPnP) and enhanced by the addition of TmMutL. In addition, TmMutS2 suppressed the TmRecA-mediated DNA strand exchange reaction in a TmMutL-dependent manner. We also demonstrated that small-angle X-ray scattering (SAXS) analysis of dimeric TmMutS2 exhibited nucleotide- and DNA-dependent conformational transitions. Particularly, TmMutS2-ADPnP showed the most compressed form rather than apo-TmMutS2 and the TmMutS2-ADP complex, in accordance with the results of biochemical assays. In the case of the DNA-binding complexes, the stretched conformation appeared in the TmMutS2-four-way junction (FWJ)-DNA complex. Convergences of biochemical- and SAXS analysis provided abundant information for TmMutS2 and clarified ambiguous experimental results.
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Affiliation(s)
- Euiyoung Jeong
- Department of Chemistry, Pohang University of Science and Technology, Pohang, Gyungbuk, South Korea
| | - Hunho Jo
- Department of Chemistry, Pohang University of Science and Technology, Pohang, Gyungbuk, South Korea
| | - Tae Gyun Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang, Gyungbuk, South Korea
| | - Changill Ban
- Department of Chemistry, Pohang University of Science and Technology, Pohang, Gyungbuk, South Korea
- * E-mail:
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12
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Jeong EY, Kim TG, Ban C. Modulated nicking endonuclease function by the N-terminal extended region of the smr domain in human Bcl-3 binding protein. Proteins 2011; 80:327-32. [DOI: 10.1002/prot.23211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/09/2011] [Accepted: 09/22/2011] [Indexed: 11/07/2022]
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13
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Fukui K, Kuramitsu S. Structure and Function of the Small MutS-Related Domain. Mol Biol Int 2011; 2011:691735. [PMID: 22091410 PMCID: PMC3200294 DOI: 10.4061/2011/691735] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 05/13/2011] [Indexed: 01/04/2023] Open
Abstract
MutS family proteins are widely distributed in almost all organisms from bacteria to human and play central roles in various DNA transactions such as DNA mismatch repair and recombinational events. The small MutS-related (Smr) domain was originally found in the C-terminal domain of an antirecombination protein, MutS2, a member of the MutS family. MutS2 is thought to suppress homologous recombination by endonucleolytic resolution of early intermediates in the process. The endonuclease activity of MutS2 is derived from the Smr domain. Interestingly, sequences homologous to the Smr domain are abundant in a variety of proteins other than MutS2 and can be classified into 3 subfamilies. Recently, the tertiary structures and endonuclease activities of all 3 Smr subfamilies were reported. In this paper, we review the biochemical characteristics and structures of the Smr domains as well as cellular functions of the Smr-containing proteins.
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Affiliation(s)
- Kenji Fukui
- RIKEN SPring-8 Center, Harima Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
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14
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Inactivation of the DNA repair genes mutS, mutL or the anti-recombination gene mutS2 leads to activation of vitamin B1 biosynthesis genes. PLoS One 2011; 6:e19053. [PMID: 21552516 PMCID: PMC3084264 DOI: 10.1371/journal.pone.0019053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 03/22/2011] [Indexed: 11/20/2022] Open
Abstract
Oxidative stress generates harmful reactive oxygen species (ROS) that attack biomolecules including DNA. In living cells, there are several mechanisms for detoxifying ROS and repairing oxidatively-damaged DNA. In this study, transcriptomic analyses clarified that disruption of DNA repair genes mutS and mutL, or the anti-recombination gene mutS2, in Thermus thermophilus HB8, induces the biosynthesis pathway for vitamin B1, which can serve as an ROS scavenger. In addition, disruption of mutS, mutL, or mutS2 resulted in an increased rate of oxidative stress-induced mutagenesis. Co-immunoprecipitation and pull-down experiments revealed previously-unknown interactions of MutS2 with MutS and MutL, indicating that these proteins cooperatively participate in the repair of oxidatively damaged DNA. These results suggested that bacterial cells sense the accumulation of oxidative DNA damage or absence of DNA repair activity, and signal the information to the transcriptional regulation machinery for an ROS-detoxifying system.
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15
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Crystal structure of YdaL, a stand-alone small MutS-related protein from Escherichia coli. J Struct Biol 2011; 174:282-9. [PMID: 21276852 DOI: 10.1016/j.jsb.2011.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 01/11/2011] [Accepted: 01/20/2011] [Indexed: 11/21/2022]
Abstract
Sequence homologs of the small MutS-related (Smr) domain, the C-terminal endonuclease domain of MutS2, also exist as stand-alone proteins. In this study, we report the crystal structure of a proteolyzed fragment of YdaL (YdaL₃₉-₁₇₅), a stand-alone Smr protein from Escherichia coli. In this structure, residues 86-170 assemble into a classical Smr core domain and are embraced by an N-terminal extension (residues 40-85) with an α/β/α fold. Sequence alignment indicates that the N-terminal extension is conserved among a number of stand-alone Smr proteins, suggesting structural diversity among Smr domains. We also discovered that the DNA binding affinity and endonuclease activity of the truncated YdaL₃₉-₁₇₅ protein were slightly lower than those of full-length YdaL₁-₁₈₇, suggesting that residues 1-38 may be involved in DNA binding.
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Morita R, Nakane S, Shimada A, Inoue M, Iino H, Wakamatsu T, Fukui K, Nakagawa N, Masui R, Kuramitsu S. Molecular mechanisms of the whole DNA repair system: a comparison of bacterial and eukaryotic systems. J Nucleic Acids 2010; 2010:179594. [PMID: 20981145 PMCID: PMC2957137 DOI: 10.4061/2010/179594] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 07/27/2010] [Indexed: 11/20/2022] Open
Abstract
DNA is subjected to many endogenous and exogenous damages. All organisms have developed a complex network of DNA repair mechanisms. A variety of different DNA repair pathways have been reported: direct reversal, base excision repair, nucleotide excision repair, mismatch repair, and recombination repair pathways. Recent studies of the fundamental mechanisms for DNA repair processes have revealed a complexity beyond that initially expected, with inter- and intrapathway complementation as well as functional interactions between proteins involved in repair pathways. In this paper we give a broad overview of the whole DNA repair system and focus on the molecular basis of the repair machineries, particularly in Thermus thermophilus HB8.
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Affiliation(s)
- Rihito Morita
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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Shimada A, Masui R, Nakagawa N, Takahata Y, Kim K, Kuramitsu S, Fukui K. A novel single-stranded DNA-specific 3'-5' exonuclease, Thermus thermophilus exonuclease I, is involved in several DNA repair pathways. Nucleic Acids Res 2010; 38:5692-705. [PMID: 20457749 PMCID: PMC2943613 DOI: 10.1093/nar/gkq350] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Single-stranded DNA (ssDNA)-specific exonucleases (ssExos) are expected to be involved in a variety of DNA repair pathways corresponding to their cleavage polarities; however, the relationship between the cleavage polarity and the respective DNA repair pathways is only partially understood. To understand the cellular function of ssExos in DNA repair better, genes encoding ssExos were disrupted in Thermus thermophilus HB8 that seems to have only a single set of 5'-3' and 3'-5' ssExos unlike other model organisms. Disruption of the tthb178 gene, which was expected to encode a 3'-5' ssExo, resulted in significant increase in the sensitivity to H(2)O(2) and frequency of the spontaneous mutation rate, but scarcely affected the sensitivity to ultraviolet (UV) irradiation. In contrast, disruption of the recJ gene, which encodes a 5'-3' ssExo, showed little effect on the sensitivity to H(2)O(2), but caused increased sensitivity to UV irradiation. In vitro characterization revealed that TTHB178 possessed 3'-5' ssExo activity that degraded ssDNAs containing deaminated and methylated bases, but not those containing oxidized bases or abasic sites. Consequently, we concluded that TTHB178 is a novel 3'-5' ssExo that functions in various DNA repair systems in cooperation with or independently of RecJ. We named TTHB178 as T. thermophilus exonuclease I.
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Affiliation(s)
- Atsuhiro Shimada
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 and RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
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18
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Fukui K, Nakagawa N, Kitamura Y, Nishida Y, Masui R, Kuramitsu S. Crystal structure of MutS2 endonuclease domain and the mechanism of homologous recombination suppression. J Biol Chem 2008; 283:33417-27. [PMID: 18838375 PMCID: PMC2662267 DOI: 10.1074/jbc.m806755200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 09/24/2008] [Indexed: 11/06/2022] Open
Abstract
DNA recombination events need to be strictly regulated, because an increase in the recombinational frequency causes unfavorable alteration of genetic information. Recent studies revealed the existence of a novel anti-recombination enzyme, MutS2. However, the mechanism by which MutS2 inhibits homologous recombination has been unknown. Previously, we found that Thermus thermophilus MutS2 (ttMutS2) harbors an endonuclease activity and that this activity is confined to the C-terminal domain, whose amino acid sequence is widely conserved in a variety of proteins with unknown function from almost all organisms ranging from bacteria to man. In this study, we determined the crystal structure of the ttMutS2 endonuclease domain at 1.7-angstroms resolution, which resembles the structure of the DNase I-like catalytic domain of Escherichia coli RNase E, a sequence-nonspecific endonuclease. The N-terminal domain of ttMutS2, however, recognized branched DNA structures, including the Holliday junction and D-loop structure, a primary intermediate in homologous recombination. The full-length of ttMutS2 digested the branched DNA structures at the junction. These results indicate that ttMutS2 suppresses homologous recombination through a novel mechanism involving resolution of early intermediates.
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Affiliation(s)
- Kenji Fukui
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-gun, Hyogo, 679-5148, Japan
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19
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Diercks T, AB E, Daniels MA, de Jong RN, Besseling R, Kaptein R, Folkers GE. Solution structure and characterization of the DNA-binding activity of the B3BP-Smr domain. J Mol Biol 2008; 383:1156-70. [PMID: 18804481 DOI: 10.1016/j.jmb.2008.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/01/2008] [Accepted: 09/03/2008] [Indexed: 10/21/2022]
Abstract
The MutS1 protein recognizes unpaired bases and initiates mismatch repair, which are essential for high-fidelity DNA replication. The homologous MutS2 protein does not contribute to mismatch repair, but suppresses homologous recombination. MutS2 lacks the damage-recognition domain of MutS1, but contains an additional C-terminal extension: the small MutS-related (Smr) domain. This domain, which is present in both prokaryotes and eukaryotes, has previously been reported to bind to DNA and to possess nicking endonuclease activity. We determine here the solution structure of the functionally active Smr domain of the Bcl3-binding protein (also known as Nedd4-binding protein 2), a protein with unknown function that lacks other domains present in MutS proteins. The Smr domain adopts a two-layer alpha-beta sandwich fold, which has a structural similarity to the C-terminal domain of IF3, the R3H domain, and the N-terminal domain of DNase I. The most conserved residues are located in three loops that form a contiguous, exposed, and positively charged surface with distinct sequence identity for prokaryotic and eukaryotic Smr domains. NMR titration experiments and DNA binding studies using Bcl3-binding protein-Smr domain mutants suggested that these most conserved loop regions participate in DNA binding to single-stranded/double-stranded DNA junctions. Based on the observed DNA-binding-induced multimerization, the structural similarity with both subdomains of DNase I, and the experimentally identified DNA-binding surface, we propose a model for DNA recognition by the Smr domain.
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Affiliation(s)
- Tammo Diercks
- Bijvoet Center for Biomolecular Research, Department of NMR Spectroscopy, Faculty of Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Lin Z, Nei M, Ma H. The origins and early evolution of DNA mismatch repair genes--multiple horizontal gene transfers and co-evolution. Nucleic Acids Res 2007; 35:7591-603. [PMID: 17965091 PMCID: PMC2190696 DOI: 10.1093/nar/gkm921] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To understand the evolutionary process of the DNA mismatch repair system, we conducted systematic phylogenetic analysis of its key components, the bacterial MutS and MutL genes and their eukaryotic homologs. Based on genome-wide homolog searches, we identified three new MutS subfamilies (MutS3-5) in addition to the previously studied MutS1 and MutS2 subfamilies. Detailed evolutionary analysis strongly suggests that frequent ancient horizontal gene transfer (HGT) occurred with both MutS and MutL genes from bacteria to eukaryotes and/or archaea. Our results further imply that the origins of mismatch repair system in eukaryotes and archaea are largely attributed to ancient HGT from bacteria instead of vertical evolution. Specifically, the eukaryotic MutS and MutL homologs likely originated from endosymbiotic ancestors of mitochondria or chloroplasts, indicating that not only archaea, but also bacteria are important sources of eukaryotic DNA metabolic genes. The archaeal MutS1 and MutL homologs were also acquired from bacteria simultaneously through HGT. Moreover, the distribution and evolution profiles of the MutS1 and MutL genes suggest that they have undergone long-term coevolution. Our work presents an overall portrait of the evolution of these important genes in DNA metabolism and also provides further understanding about the early evolution of cellular organisms.
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Affiliation(s)
- Zhenguo Lin
- Department of Biology and Institute of Molecular Evolutionary Genetics, Pennsylvania State University, University Park, PA 16802, USA
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Fukui K, Takahata Y, Nakagawa N, Kuramitsu S, Masui R. Analysis of a nuclease activity of catalytic domain of Thermus thermophilus MutS2 by high-accuracy mass spectrometry. Nucleic Acids Res 2007; 35:e100. [PMID: 17686785 PMCID: PMC1976465 DOI: 10.1093/nar/gkm575] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Electrospray ionization with Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FT ICR MS) is a powerful tool for analyzing the precise structural features of biopolymers, including oligonucleotides. Here, we described the detailed characterization of a newly discovered nuclease activity of the C-terminal domain of Thermus thermophilus MutS2 (ttMutS2). Using this method, the length, nucleotide content and nature of the 5'- and 3'-termini of the product oligonucleotides were accurately identified. It is revealed that the C-terminal domain of ttMutS2 incised the phosphate backbone of oligodeoxynucleotides non-sequence-specifically at the 3' side of the phosphates. The simultaneous identification of the innumerable fragments was achieved by the extremely high-accuracy of ESI-FT ICR MS.
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Affiliation(s)
- Kenji Fukui
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 and Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Yoshio Takahata
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 and Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Noriko Nakagawa
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 and Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Seiki Kuramitsu
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 and Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Ryoji Masui
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 and Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
- *To whom correspondence should be addressed.+81 06 6850 5433+81 06 6850 5442
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Fukui K, Kosaka H, Kuramitsu S, Masui R. Nuclease activity of the MutS homologue MutS2 from Thermus thermophilus is confined to the Smr domain. Nucleic Acids Res 2007; 35:850-60. [PMID: 17215294 PMCID: PMC1807967 DOI: 10.1093/nar/gkl735] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
MutS homologues are highly conserved enzymes engaged in DNA mismatch repair (MMR), meiotic recombination and other DNA modifications. Genome sequencing projects have revealed that bacteria and plants possess a MutS homologue, MutS2. MutS2 lacks the mismatch-recognition domain of MutS, but contains an extra C-terminal region called the small MutS-related (Smr) domain. Sequences homologous to the Smr domain are annotated as ‘proteins of unknown function’ in various organisms ranging from bacteria to human. Although recent in vivo studies indicate that MutS2 plays an important role in recombinational events, there had been only limited characterization of the biochemical function of MutS2 and the Smr domain. We previously established that Thermus thermophilus MutS2 (ttMutS2) possesses endonuclease activity. In this study, we report that a Smr-deleted ttMutS2 mutant retains the dimerization, ATPase and DNA-binding activities, but has no endonuclease activity. Furthermore, the Smr domain alone was stable and functional in binding and incising DNA. It is noteworthy that an endonuclease activity is associated with a MutS homologue, which is generally thought to recognize specific DNA structures.
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Affiliation(s)
- Kenji Fukui
- Department of Biological Sciences, Graduate School of Science, Osaka UniversityToyonaka, Osaka 560-0043, Japan
| | - Hiromichi Kosaka
- Department of Biological Sciences, Graduate School of Science, Osaka UniversityToyonaka, Osaka 560-0043, Japan
| | - Seiki Kuramitsu
- Department of Biological Sciences, Graduate School of Science, Osaka UniversityToyonaka, Osaka 560-0043, Japan
- RIKEN SPring-8 Center, Harima Institute1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Ryoji Masui
- Department of Biological Sciences, Graduate School of Science, Osaka UniversityToyonaka, Osaka 560-0043, Japan
- RIKEN SPring-8 Center, Harima Institute1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
- To whom correspondence should be addressed at Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyamacho, Toyonaka, Osaka 560-0043, Japan. Tel: +81 06 6850 5433; Fax: +81 06 6850 5442;
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Dunin-Horkawicz S, Feder M, Bujnicki JM. Phylogenomic analysis of the GIY-YIG nuclease superfamily. BMC Genomics 2006; 7:98. [PMID: 16646971 PMCID: PMC1564403 DOI: 10.1186/1471-2164-7-98] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2006] [Accepted: 04/28/2006] [Indexed: 11/28/2022] Open
Abstract
Background The GIY-YIG domain was initially identified in homing endonucleases and later in other selfish mobile genetic elements (including restriction enzymes and non-LTR retrotransposons) and in enzymes involved in DNA repair and recombination. However, to date no systematic search for novel members of the GIY-YIG superfamily or comparative analysis of these enzymes has been reported. Results We carried out database searches to identify all members of known GIY-YIG nuclease families. Multiple sequence alignments together with predicted secondary structures of identified families were represented as Hidden Markov Models (HMM) and compared by the HHsearch method to the uncharacterized protein families gathered in the COG, KOG, and PFAM databases. This analysis allowed for extending the GIY-YIG superfamily to include members of COG3680 and a number of proteins not classified in COGs and to predict that these proteins may function as nucleases, potentially involved in DNA recombination and/or repair. Finally, all old and new members of the GIY-YIG superfamily were compared and analyzed to infer the phylogenetic tree. Conclusion An evolutionary classification of the GIY-YIG superfamily is presented for the very first time, along with the structural annotation of all (sub)families. It provides a comprehensive picture of sequence-structure-function relationships in this superfamily of nucleases, which will help to design experiments to study the mechanism of action of known members (especially the uncharacterized ones) and will facilitate the prediction of function for the newly discovered ones.
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Affiliation(s)
- Stanislaw Dunin-Horkawicz
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
| | - Marcin Feder
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
| | - Janusz M Bujnicki
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland
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Wang G, Alamuri P, Humayun MZ, Taylor DE, Maier RJ. The Helicobacter pylori MutS protein confers protection from oxidative DNA damage. Mol Microbiol 2006; 58:166-76. [PMID: 16164556 DOI: 10.1111/j.1365-2958.2005.04833.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The human gastric pathogenic bacterium Helicobacter pylori lacks a MutSLH-like DNA mismatch repair system. Here, we have investigated the functional roles of a mutS homologue found in H. pylori, and show that it plays an important physiological role in repairing oxidative DNA damage. H. pylori mutS mutants are more sensitive than wild-type cells to oxidative stress induced by agents such as H2O2, paraquat or oxygen. Exposure of mutS cells to oxidative stress results in a significant ( approximately 10-fold) elevation of mutagenesis. Strikingly, most mutations in mutS cells under oxidative stress condition are G:C to T:A transversions, a signature of 8-oxoguanine (8-oxoG). Purified H. pylori MutS protein binds with a high specific affinity to double-stranded DNA (dsDNA) containing 8-oxoG as well as to DNA Holliday junction structures, but only weakly to dsDNA containing a G:A mismatch. Under oxidative stress conditions, mutS cells accumulate higher levels (approximately threefold) of 8-oxoG DNA lesions than wild-type cells. Finally, we observe that mutS mutant cells have reduced colonization capacity in comparison to wild-type cells in a mouse infection model.
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Affiliation(s)
- Ge Wang
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Kang J, Huang S, Blaser MJ. Structural and functional divergence of MutS2 from bacterial MutS1 and eukaryotic MSH4-MSH5 homologs. J Bacteriol 2005; 187:3528-37. [PMID: 15866941 PMCID: PMC1112012 DOI: 10.1128/jb.187.10.3528-3537.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
MutS homologs, identified in nearly all bacteria and eukaryotes, include the bacterial proteins MutS1 and MutS2 and the eukaryotic MutS homologs 1 to 7, and they often are involved in recognition and repair of mismatched bases and small insertion/deletions, thereby limiting illegitimate recombination and spontaneous mutation. To explore the relationship of MutS2 to other MutS homologs, we examined conserved protein domains. Fundamental differences in structure between MutS2 and other MutS homologs suggest that MutS1 and MutS2 diverged early during evolution, with all eukaryotic homologs arising from a MutS1 ancestor. Data from MutS1 crystal structures, biochemical results from MutS2 analyses, and our phylogenetic studies suggest that MutS2 has functions distinct from other members of the MutS family. A mutS2 mutant was constructed in Helicobacter pylori, which lacks mutS1 and mismatch repair genes mutL and mutH. We show that MutS2 plays no role in mismatch or recombinational repair or deletion between direct DNA repeats. In contrast, MutS2 plays a significant role in limiting intergenomic recombination across a range of donor DNA tested. This phenotypic analysis is consistent with the phylogenetic and biochemical data suggesting that MutS1 and MutS2 have divergent functions.
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Affiliation(s)
- Josephine Kang
- Department of Microbiology, New York University School of Medicine, and VA Medical Center, New York, NY 10016, USA.
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Pinto AV, Mathieu A, Marsin S, Veaute X, Ielpi L, Labigne A, Radicella JP. Suppression of Homologous and Homeologous Recombination by the Bacterial MutS2 Protein. Mol Cell 2005; 17:113-20. [PMID: 15629722 DOI: 10.1016/j.molcel.2004.11.035] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 10/01/2004] [Accepted: 10/26/2004] [Indexed: 10/26/2022]
Abstract
In addition to their role in DNA repair, recombination events are associated with processes aimed at providing the genetic variability needed for adaptation and evolution of a population. In bacteria, recombination is involved in the appearance of new variants by allowing the incorporation of exogenous DNA or the reshuffling of endogenous sequences. Here we show that HpMutS2, a protein belonging to the MutS2 family in Helicobacter pylori, is not involved in mismatch repair but inhibits homologous and homeologous recombination. Disruption of HpmutS2 leads to an increased efficiency of exogenous DNA incorporation. HpMutS2 has a selective affinity for DNA structures mimicking recombination intermediates with no specificity for homoduplex DNA or mismatches. The purified protein has an ATPase activity stimulated by the same DNA structures. Finally, we show that HpMutS2 inhibits DNA strand exchange reactions in vitro. Thus, MutS2 proteins are candidates for controlling recombination and therefore genetic diversity in bacteria.
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Affiliation(s)
- A Viviana Pinto
- Département de Radiobiologie et Radiopathologie, UMR217 CNRS/CEA, Commissariat à l'Energie Atomique, BP 6, F-92265 Fontenay aux Roses, France
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