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Klucnika A, Mu P, Jezek J, McCormack M, Di Y, Bradshaw CR, Ma H. REC drives recombination to repair double-strand breaks in animal mtDNA. J Cell Biol 2023; 222:e202201137. [PMID: 36355348 PMCID: PMC9652705 DOI: 10.1083/jcb.202201137] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 09/09/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Mechanisms that safeguard mitochondrial DNA (mtDNA) limit the accumulation of mutations linked to mitochondrial and age-related diseases. Yet, pathways that repair double-strand breaks (DSBs) in animal mitochondria are poorly understood. By performing a candidate screen for mtDNA repair proteins, we identify that REC-an MCM helicase that drives meiotic recombination in the nucleus-also localizes to mitochondria in Drosophila. We show that REC repairs mtDNA DSBs by homologous recombination in somatic and germline tissues. Moreover, REC prevents age-associated mtDNA mutations. We further show that MCM8, the human ortholog of REC, also localizes to mitochondria and limits the accumulation of mtDNA mutations. This study provides mechanistic insight into animal mtDNA recombination and demonstrates its importance in safeguarding mtDNA during ageing and evolution.
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Affiliation(s)
- Anna Klucnika
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Peiqiang Mu
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jan Jezek
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Matthew McCormack
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Ying Di
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | | | - Hansong Ma
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
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2
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Hatkevich T, Boudreau V, Rubin T, Maddox PS, Huynh JR, Sekelsky J. Centromeric SMC1 promotes centromere clustering and stabilizes meiotic homolog pairing. PLoS Genet 2019; 15:e1008412. [PMID: 31609962 PMCID: PMC6812850 DOI: 10.1371/journal.pgen.1008412] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/24/2019] [Accepted: 09/10/2019] [Indexed: 01/16/2023] Open
Abstract
During meiosis, each chromosome must selectively pair and synapse with its own unique homolog to enable crossover formation and subsequent segregation. How homolog pairing is maintained in early meiosis to ensure synapsis occurs exclusively between homologs is unknown. We aimed to further understand this process by examining the meiotic defects of a unique Drosophila mutant, Mcm5A7. We found that Mcm5A7 mutants are proficient in homolog pairing at meiotic onset yet fail to maintain pairing as meiotic synapsis ensues, causing seemingly normal synapsis between non-homologous loci. This pairing defect corresponds with a reduction of SMC1-dependent centromere clustering at meiotic onset. Overexpressing SMC1 in this mutant significantly restores centromere clustering, homolog pairing, and crossover formation. These data indicate that the initial meiotic pairing of homologs is not sufficient to yield synapsis exclusively between homologs and provide a model in which meiotic homolog pairing must be stabilized by centromeric SMC1 to ensure proper synapsis. Sexually reproducing organisms must produce gametes (sperm and eggs) that have one copy of each chromosome. This is accomplished through a special cell division called meiosis. Each chromosome replicates to generate identical sister chromatids, then finds and pairs with its unique partner chromosome. A well-regulated recombination process then generates crossovers between paired maternal/paternal partners; these crossovers ensure accurate chromosome segregation in meiosis. The pairing process is very poorly understood. The Drosophila melanogaster (fruit fly) Mcm5A7 mutation was previously shown to reduce crossovers but we show here that this is due to defects in meiotic chromosome pairing. We trace the primary defect to failure to load cohesins, which hold sister chromatids together but have additional roles in meiosis, at the centromere–the region that will later direct chromosome segregation. Thus, defects in centromeric cohesion lead to loss of chromosome pairing and loss of recombination along the arms of the chromosomes, and ultimately loss of fidelity during chromosome segregation.
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Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Vincent Boudreau
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Thomas Rubin
- CIRB, Collège de France, PSL Research University, CNRS UMR7241, Inserm U1050, Paris, France
| | - Paul S. Maddox
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Jean-René Huynh
- CIRB, Collège de France, PSL Research University, CNRS UMR7241, Inserm U1050, Paris, France
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Integrative Program in Biological and Genome Sciences, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * E-mail:
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3
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Meiotic MCM Proteins Promote and Inhibit Crossovers During Meiotic Recombination. Genetics 2019; 212:461-468. [PMID: 31028111 PMCID: PMC6553819 DOI: 10.1534/genetics.119.302221] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/22/2019] [Indexed: 01/29/2023] Open
Abstract
Crossover formation as a result of meiotic recombination is vital for the proper segregation of homologous chromosomes at the end of meiosis I. In many organisms, crossovers are generated through two crossover pathways: Class I and Class II. To ensure accurate crossover formation, meiosis-specific protein complexes regulate the degree to which each pathway is used. One such complex is the mei-mini-chromosome maintenance (MCM) complex, which contains MCM and MCM-like proteins REC (ortholog of Mcm8), MEI-217, and MEI-218. The mei-MCM complex genetically promotes Class I crossovers and inhibits Class II crossovers in Drosophila, but it is unclear how individual mei-MCM proteins contribute to crossover regulation. In this study, we perform genetic analyses to understand how specific regions and motifs of mei-MCM proteins contribute to Class I and II crossover formation, and distribution. Our analyses show that the long, disordered N-terminus of MEI-218 is dispensable for crossover formation, and that mutations that disrupt REC’s Walker A and B motifs differentially affect Class I and Class II crossover formation. In rec Walker A mutants, Class I crossovers exhibit no change but Class II crossovers are increased. However, in rec Walker B mutants, Class I crossovers are severely impaired and Class II crossovers are increased. These results suggest that REC may form multiple complexes that exhibit differential REC-dependent ATP-binding and -hydrolyzing requirements. These results provide genetic insight into the mechanisms through which mei-MCM proteins promote Class I crossovers and inhibit Class II crossovers.
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4
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John A, Vinayan K, Varghese J. Achiasmy: Male Fruit Flies Are Not Ready to Mix. Front Cell Dev Biol 2016; 4:75. [PMID: 27486580 PMCID: PMC4949207 DOI: 10.3389/fcell.2016.00075] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/29/2016] [Indexed: 11/13/2022] Open
Abstract
Maintenance of the chromosomal copy number over generations and recombination between homologous chromosomes are hallmarks of meiotic cell division. This genetic exchange that take place during gamete formation leads to genetic diversity, the main driving force behind natural selection. Formation of chiasmata, the physical link between homologous chromosomes during meiosis, is a requisite for recombination. In addition, chiasmata also aid in proper segregation of homologous chromosomes and has a major impact on reproductive fitness. Given these facts it is intriguing that many insect species have forgone the need for genetic exchange between homologous chromosomes during meiosis. Geneticists for several decades knew that meiotic crossover and recombination is absent in Drosophila males and some female lepidopterans, a condition termed achiasmy. However, a good understanding of the mechanisms that cause achiasmy and the evolutionary benefits of achiasmy is currently lacking. In this article we will discuss possible genetic and molecular basis of achiasmy in male Drosophila.
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Affiliation(s)
- Alphy John
- Drosophila Research in Energy and Metabolism Lab, School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, India
| | - Kavya Vinayan
- Drosophila Research in Energy and Metabolism Lab, School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, India
| | - Jishy Varghese
- Drosophila Research in Energy and Metabolism Lab, School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, India
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5
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Abstract
The study of homologous recombination has its historical roots in meiosis. In this context, recombination occurs as a programmed event that culminates in the formation of crossovers, which are essential for accurate chromosome segregation and create new combinations of parental alleles. Thus, meiotic recombination underlies both the independent assortment of parental chromosomes and genetic linkage. This review highlights the features of meiotic recombination that distinguish it from recombinational repair in somatic cells, and how the molecular processes of meiotic recombination are embedded and interdependent with the chromosome structures that characterize meiotic prophase. A more in-depth review presents our understanding of how crossover and noncrossover pathways of meiotic recombination are differentiated and regulated. The final section of this review summarizes the studies that have defined defective recombination as a leading cause of pregnancy loss and congenital disease in humans.
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Affiliation(s)
- Neil Hunter
- Howard Hughes Medical Institute, Department of Microbiology & Molecular Genetics, Department of Molecular & Cellular Biology, Department of Cell Biology & Human Anatomy, University of California Davis, Davis, California 95616
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6
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Lake CM, Nielsen RJ, Guo F, Unruh JR, Slaughter BD, Hawley RS. Vilya, a component of the recombination nodule, is required for meiotic double-strand break formation in Drosophila. eLife 2015; 4:e08287. [PMID: 26452093 PMCID: PMC4703084 DOI: 10.7554/elife.08287] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/08/2015] [Indexed: 01/25/2023] Open
Abstract
Meiotic recombination begins with the induction of programmed double-strand breaks (DSBs). In most organisms only a fraction of DSBs become crossovers. Here we report a novel meiotic gene, vilya, which encodes a protein with homology to Zip3-like proteins shown to determine DSB fate in other organisms. Vilya is required for meiotic DSB formation, perhaps as a consequence of its interaction with the DSB accessory protein Mei-P22, and localizes to those DSB sites that will mature into crossovers. In early pachytene Vilya localizes along the central region of the synaptonemal complex and to discrete foci. The accumulation of Vilya at foci is dependent on DSB formation. Immuno-electron microscopy demonstrates that Vilya is a component of recombination nodules, which mark the sites of crossover formation. Thus Vilya links the mechanism of DSB formation to either the selection of those DSBs that will become crossovers or to the actual process of crossing over.
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Affiliation(s)
- Cathleen M Lake
- Stowers Institute for Medical Research, Kansas City, United States
| | - Rachel J Nielsen
- Stowers Institute for Medical Research, Kansas City, United States
| | - Fengli Guo
- Stowers Institute for Medical Research, Kansas City, United States
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, United States
| | | | - R Scott Hawley
- Stowers Institute for Medical Research, Kansas City, United States.,Department of Molecular and Integrative Physiology, Kansas University Medical Center, Kansas City, United States
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7
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Gambus A, Blow JJ. Mcm8 and Mcm9 form a dimeric complex in Xenopus laevis egg extract that is not essential for DNA replication initiation. Cell Cycle 2013; 12:1225-32. [PMID: 23518502 PMCID: PMC3674087 DOI: 10.4161/cc.24310] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 03/12/2013] [Accepted: 03/14/2013] [Indexed: 11/22/2022] Open
Abstract
Hexameric complexes of the six related Mcm2-7 proteins form the core of the replicative helicase. Two other proteins, Mcm8 and Mcm9, with significant homology to Mcm2-7 were first shown to play distinct roles during DNA replication in Xenopus laevis egg extract. Recent work has revealed that Mcm8 and 9 form a complex that plays a role during homologous recombination in human, chicken and mouse cells. We have therefore re-examined the behavior of the Xenopus homologs of these proteins. We show that Mcm8 and Mcm9 form a dimeric complex in Xenopus egg extract. They both associate with chromatin at later stages of DNA replication, and this association is stimulated by DNA damage, suggesting that their function is analogous to the one described in higher eukaryotes. In contrast to previous reports, we do not find Mcm9 essential for loading of Mcm2-7 complex onto chromatin during origin licensing nor detect its interaction with Cdt1 origin licensing factor. Altogether, we conclude that the role Mcm8 and Mcm9 play in Xenopus egg extract is not different from recent findings in higher eukaryotes, consistent with an evolutionary conservation of their function.
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Affiliation(s)
- Agnieszka Gambus
- School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
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8
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A germline clone screen on the X chromosome reveals novel meiotic mutants in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2012; 2:1369-77. [PMID: 23173088 PMCID: PMC3484667 DOI: 10.1534/g3.112.003723] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 09/06/2012] [Indexed: 11/28/2022]
Abstract
In an effort to isolate novel meiotic mutants that are severely defective in chromosome segregation and/or exchange, we employed a germline clone screen of the X chromosome of Drosophila melanogaster. We screened over 120,000 EMS-mutagenized chromosomes and isolated 19 mutants, which comprised nine complementation groups. Four of these complementation groups mapped to known meiotic genes, including mei-217, mei-218, mei-9, and nod. Importantly, we have identified two novel complementation groups with strong meiotic phenotypes, as assayed by X chromosome nondisjunction. One complementation group is defined by three alleles, and the second novel complementation group is defined by a single allele. All 19 mutants are homozygous viable, fertile, and fully recessive. Of the 9 mutants that have been molecularly characterized, 5 are canonical EMS-induced transitions, and the remaining 4 are transversions. In sum, we have identified two new genes that are defined by novel meiotic mutants, in addition to isolating new alleles of mei-217, mei-218, mei-9, and nod.
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9
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Nishimura K, Ishiai M, Horikawa K, Fukagawa T, Takata M, Takisawa H, Kanemaki MT. Mcm8 and Mcm9 form a complex that functions in homologous recombination repair induced by DNA interstrand crosslinks. Mol Cell 2012; 47:511-22. [PMID: 22771115 DOI: 10.1016/j.molcel.2012.05.047] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 05/14/2012] [Accepted: 05/31/2012] [Indexed: 01/09/2023]
Abstract
DNA interstrand crosslinks (ICLs) are highly toxic lesions that stall the replication fork to initiate the repair process during the S phase of vertebrates. Proteins involved in Fanconi anemia (FA), nucleotide excision repair (NER), and translesion synthesis (TS) collaboratively lead to homologous recombination (HR) repair. However, it is not understood how ICL-induced HR repair is carried out and completed. Here, we showed that the replicative helicase-related Mcm family of proteins, Mcm8 and Mcm9, forms a complex required for HR repair induced by ICLs. Chicken DT40 cells lacking MCM8 or MCM9 are viable but highly sensitive to ICL-inducing agents, and exhibit more chromosome aberrations in the presence of mitomycin C compared with wild-type cells. During ICL repair, Mcm8 and Mcm9 form nuclear foci that partly colocalize with Rad51. Mcm8-9 works downstream of the FA and BRCA2/Rad51 pathways, and is required for HR that promotes sister chromatid exchanges, probably as a hexameric ATPase/helicase.
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Affiliation(s)
- Kohei Nishimura
- Center for Frontier Research, National Institute of Genetics, Research Organization of Information and Systems, Yata 1111, Mishima, Shizuoka 411-8540, Japan
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10
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Lake CM, Hawley RS. The molecular control of meiotic chromosomal behavior: events in early meiotic prophase in Drosophila oocytes. Annu Rev Physiol 2012; 74:425-51. [PMID: 22335798 DOI: 10.1146/annurev-physiol-020911-153342] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We review the critical events in early meiotic prophase in Drosophila melanogaster oocytes. We focus on four aspects of this process: the formation of the synaptonemal complex (SC) and its role in maintaining homologous chromosome pairings, the critical roles of the meiosis-specific process of centromere clustering in the formation of a full-length SC, the mechanisms by which preprogrammed double-strand breaks initiate meiotic recombination, and the checkpoints that govern the progression and coordination of these processes. Central to this discussion are the roles that somatic pairing events play in establishing the necessary conditions for proper SC formation, the roles of centromere pairing in synapsis initiation, and the mechanisms by which oocytes detect failures in SC formation and/or recombination. Finally, we correlate what is known in Drosophila oocytes with our understanding of these processes in other systems.
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Affiliation(s)
- Cathleen M Lake
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
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11
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Shingu Y, Tokai T, Agawa Y, Toyota K, Ahamed S, Kawagishi-Kobayashi M, Komatsu A, Mikawa T, Yamamoto MT, Wakasa K, Shibata T, Kusano K. The double-stranded break-forming activity of plant SPO11s and a novel rice SPO11 revealed by a Drosophila bioassay. BMC Mol Biol 2012; 13:1. [PMID: 22248237 PMCID: PMC3273433 DOI: 10.1186/1471-2199-13-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 01/16/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND SPO11 is a key protein for promoting meiotic recombination, by generating chromatin locus- and timing-specific DNA double-strand breaks (DSBs). The DSB activity of SPO11 was shown by genetic analyses, but whether SPO11 exerts DSB-forming activity by itself is still an unanswered question. DSB formation by SPO11 has not been detected by biochemical means, probably because of a lack of proper protein-folding, posttranslational modifications, and/or specific SPO11-interacting proteins required for this activity. In addition, plants have multiple SPO11-homologues. RESULTS To determine whether SPO11 can cleave DNA by itself, and to identify which plant SPO11 homologue cleaves DNA, we developed a Drosophila bioassay system that detects the DSB signals generated by a plant SPO11 homologue expressed ectopically. We cytologically and genetically demonstrated the DSB activities of Arabidopsis AtSPO11-1 and AtSPO11-2, which are required for meiosis, in the absence of other plant proteins. Using this bioassay, we further found that a novel SPO11-homologue, OsSPO11D, which has no counterpart in Arabidopsis, displays prominent DSB-forming activity. Quantitative analyses of the rice SPO11 transcripts revealed the specific increase in OsSPO11D mRNA in the anthers containing meiotic pollen mother cells. CONCLUSIONS The Drosophila bioassay system successfully demonstrated that some plant SPO11 orthologues have intrinsic DSB activities. Furthermore, we identified a novel SPO11 homologue, OsSPO11D, with robust DSB activity and a possible meiotic function.
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Affiliation(s)
- Yoshinori Shingu
- Cellular & Molecular Biology Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Takeshi Tokai
- Department of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan
| | - Yasuo Agawa
- Center for Genetic Resource Education & Development, Kyoto Institute of Technology, Saga-Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Kentaro Toyota
- Department of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan
| | - Selina Ahamed
- Department of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan
| | | | - Akira Komatsu
- National Institute of Crop Science, 2-1-8 Kannondai, Tsukuba, Ibaraki 305-8518, Japan
| | - Tsutomu Mikawa
- Cellular & Molecular Biology Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Masa-Toshi Yamamoto
- Center for Genetic Resource Education & Development, Kyoto Institute of Technology, Saga-Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
| | - Kyo Wakasa
- Department of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan
| | - Takehiko Shibata
- Cellular & Molecular Biology Laboratory, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Kohji Kusano
- Center for Genetic Resource Education & Development, Kyoto Institute of Technology, Saga-Ippongi-cho, Ukyo-ku, Kyoto 616-8354, Japan
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12
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Aves SJ, Liu Y, Richards TA. Evolutionary diversification of eukaryotic DNA replication machinery. Subcell Biochem 2012; 62:19-35. [PMID: 22918578 DOI: 10.1007/978-94-007-4572-8_2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
DNA replication research to date has focused on model organisms such as the vertebrate Xenopus laevis and the yeast species Saccharomyces cerevisiae and Schizosaccharomyces pombe. However, animals and fungi both belong to the Opisthokonta, one of about six eukaryotic phylogenetic 'supergroups', and therefore represent only a fraction of eukaryotic diversity. To explore evolutionary diversification of the eukaryotic DNA replication machinery a bioinformatic approach was used to investigate the presence or absence of yeast/animal replisome components in other eukaryotic taxa. A comparative genomic survey was undertaken of 59 DNA replication proteins in a diverse range of 36 eukaryotes from all six supergroups. Twenty-three proteins including Mcm2-7, Cdc45, RPA1, primase, some DNA polymerase subunits, RFC1-5, PCNA and Fen1 are present in all species examined. A further 20 proteins are present in all six eukaryotic supergroups, although not necessarily in every species: with the exception of RNase H2B and the fork protection complex component Timeless/Tof1, all of these are members of anciently derived paralogous families such as ORC, MCM, GINS or RPA. Together these form a set of 43 proteins that must have been present in the last common eukaryotic ancestor (LCEA). This minimal LCEA replisome is significantly more complex than the related replisome in Archaea, indicating evolutionary events including duplications of DNA replication genes in the LCEA lineage which parallel the early evolution of other complex eukaryotic cellular features.
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Affiliation(s)
- Stephen J Aves
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK,
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13
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Li JJ, Schnick J, Hayles J, MacNeill SA. Purification and functional inactivation of the fission yeast MCM(MCM-BP) complex. FEBS Lett 2011; 585:3850-5. [PMID: 22036784 DOI: 10.1016/j.febslet.2011.10.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 10/09/2011] [Accepted: 10/14/2011] [Indexed: 12/31/2022]
Abstract
The MCM (mini-chromosome maintenance) complex is the core of the eukaryotic replicative helicase and comprises six proteins, Mcm2-Mcm7. In humans, a variant form of the complex has Mcm2 replaced by the MCM-BP protein. Recent results suggest that a similar complex exists in fission yeast with an essential role in DNA replication and cell cycle progression. Here, we describe the purification and subunit composition of the fission yeast MCM(Mcb1) complex. Using newly generated temperature-sensitive alleles, we show that loss of MCM(Mcb1) function leads to accumulation of DNA damage, checkpoint activation and cell cycle arrest, and provide evidence for a role for MCM(Mcb1) in meiosis.
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Affiliation(s)
- Juan-juan Li
- Cancer Research UK London Research Institute, London, UK
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14
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Lake CM, Nielsen RJ, Hawley RS. The Drosophila zinc finger protein trade embargo is required for double strand break formation in meiosis. PLoS Genet 2011; 7:e1002005. [PMID: 21383963 PMCID: PMC3044681 DOI: 10.1371/journal.pgen.1002005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Accepted: 12/21/2010] [Indexed: 11/18/2022] Open
Abstract
Homologous recombination in meiosis is initiated by the programmed induction of double strand breaks (DSBs). Although the Drosophila Spo11 ortholog Mei-W68 is required for the induction of DSBs during meiotic prophase, only one other protein (Mei-P22) has been shown to be required for Mei-W68 to exert this function. We show here that the chromatin-associated protein Trade Embargo (Trem), a C2H2 zinc finger protein, is required to localize Mei-P22 to discrete foci on meiotic chromosomes, and thus to promote the formation of DSBs, making Trem the earliest known function in the process of DSB formation in Drosophila oocytes. We speculate that Trem may act by either directing the binding of Mei-P22 to preferred sites of DSB formation or by altering chromatin structure in a manner that allows Mei-P22 to form foci.
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Affiliation(s)
- Cathleen M Lake
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America.
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15
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Abstract
The eukaryotic MCM2-7 complex is recruited onto origins of replication during the G1 phase of the cell cycle and acts as the main helicase at the replication fork during the S phase. Over the last few years a number of structural reports on MCM proteins using both electron microscopy and protein crystallography have been published. The crystal structures of two (almost) full-length archaeal homologs provide the first atomic pictures of a MCM helicase. However one of the structures is at low resolution and the other is of an inactive MCM. Moreover, both proteins are monomeric in the crystal, whereas the activity of the complex is critically dependent on oligomerization. Lower resolution structures derived from electron microscopy studies are therefore crucial to complement the crystallographic analysis and to assemble the multimeric complex that is active in the cell. A critical analysis of all the structural results elucidates the potential conformational changes and dynamic behavior of MCM helicase to provide a first insight into the gamut of molecular configurations adopted during the processes of DNA melting and unwinding.
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16
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Liu Y, Richards TA, Aves SJ. Ancient diversification of eukaryotic MCM DNA replication proteins. BMC Evol Biol 2009; 9:60. [PMID: 19292915 PMCID: PMC2667178 DOI: 10.1186/1471-2148-9-60] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 03/17/2009] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Yeast and animal cells require six mini-chromosome maintenance proteins (Mcm2-7) for pre-replication complex formation, DNA replication initiation and DNA synthesis. These six individual MCM proteins form distinct heterogeneous subunits within a hexamer which is believed to form the replicative helicase and which associates with the essential but non-homologous Mcm10 protein during DNA replication. In contrast Archaea generally only possess one MCM homologue which forms a homohexameric MCM helicase. In some eukaryotes Mcm8 and Mcm9 paralogues also appear to be involved in DNA replication although their exact roles are unclear. RESULTS We used comparative genomics and phylogenetics to reconstruct the diversification of the eukaryotic Mcm2-9 gene family, demonstrating that Mcm2-9 were formed by seven gene duplication events before the last common ancestor of the eukaryotes. Mcm2-7 protein paralogues were present in all eukaryote genomes studied suggesting that no gene loss or functional replacements have been tolerated during the evolutionary diversification of eukaryotes. Mcm8 and 9 are widely distributed in eukaryotes and group together on the MCM phylogenetic tree to the exclusion of all other MCM paralogues suggesting co-ancestry. Mcm8 and Mcm9 are absent in some taxa, including Trichomonas and Giardia, and appear to have been secondarily lost in some fungi and some animals. The presence and absence of Mcm8 and 9 is concordant in all taxa sampled with the exception of Drosophila species. Mcm10 is present in most eukaryotes sampled but shows no concordant pattern of presence or absence with Mcm8 or 9. CONCLUSION A multifaceted and heterogeneous Mcm2-7 hexamer evolved during the early evolution of the eukaryote cell in parallel with numerous other acquisitions in cell complexity and prior to the diversification of extant eukaryotes. The conservation of all six paralogues throughout the eukaryotes suggests that each Mcm2-7 hexamer component has an exclusive functional role, either by a combination of unique lock and key interactions between MCM hexamer subunits and/or by a range of novel side interactions. Mcm8 and 9 evolved early in eukaryote cell evolution and their pattern of presence or absence suggests that they may have linked functions. Mcm8 is highly divergent in all Drosophila species and may not provide a good model for Mcm8 in other eukaryotes.
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Affiliation(s)
- Yuan Liu
- School of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
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Crevel G, Hashimoto R, Vass S, Sherkow J, Yamaguchi M, Heck MM, Cotterill S. Differential requirements for MCM proteins in DNA replication in Drosophila S2 cells. PLoS One 2007; 2:e833. [PMID: 17786205 PMCID: PMC1950684 DOI: 10.1371/journal.pone.0000833] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 07/16/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The MCM2-7 proteins are crucial components of the pre replication complex (preRC) in eukaryotes. Since they are significantly more abundant than other preRC components, we were interested in determining whether the entire cellular content was necessary for DNA replication in vivo. METHODOLOGY/PRINCIPLE FINDINGS We performed a systematic depletion of the MCM proteins in Drosophila S2 cells using dsRNA-interference. Reducing MCM2-6 levels by >95-99% had no significant effect on cell cycle distribution or viability. Depletion of MCM7 however caused an S-phase arrest. MCM2-7 depletion produced no change in the number of replication forks as measured by PCNA loading. We also depleted MCM8. This caused a 30% reduction in fork number, but no significant effect on cell cycle distribution or viability. No additive effects were observed by co-depleting MCM8 and MCM5. CONCLUSIONS/SIGNIFICANCE These studies suggest that, in agreement with what has previously been observed for Xenopus in vitro, not all of the cellular content of MCM2-6 proteins is needed for normal cell cycling. They also reveal an unexpected unique role for MCM7. Finally they suggest that MCM8 has a role in DNA replication in S2 cells.
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Affiliation(s)
- Gilles Crevel
- Basic Medical Sciences, St. George's University of London, London, United Kingdom
| | - Reina Hashimoto
- Department of Applied Biology, Insect Biomedical Research Center, Kyoto Institute of Technology, Kyoto, Japan
| | - Sharron Vass
- Queen's Medical Research Institute Centre for Cardiovascular Science, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Jake Sherkow
- Queen's Medical Research Institute Centre for Cardiovascular Science, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Insect Biomedical Research Center, Kyoto Institute of Technology, Kyoto, Japan
| | - Margarete M.S. Heck
- Queen's Medical Research Institute Centre for Cardiovascular Science, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Sue Cotterill
- Basic Medical Sciences, St. George's University of London, London, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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Lake CM, Teeter K, Page SL, Nielsen R, Hawley RS. A genetic analysis of the Drosophila mcm5 gene defines a domain specifically required for meiotic recombination. Genetics 2007; 176:2151-63. [PMID: 17565942 PMCID: PMC1950621 DOI: 10.1534/genetics.107.073551] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Members of the minichromosome maintenance (MCM) family have pivotal roles in many biological processes. Although originally studied for their role in DNA replication, it is becoming increasingly apparent that certain members of this family are multifunctional and also play roles in transcription, cohesion, condensation, and recombination. Here we provide a genetic dissection of the mcm5 gene in Drosophila that demonstrates an unexpected function for this protein. First, we show that homozygotes for a null allele of mcm5 die as third instar larvae, apparently as a result of blocking those replication events that lead to mitotic divisions without impairing endo-reduplication. However, we have also recovered a viable and fertile allele of mcm5 (denoted mcm5(A7)) that specifically impairs the meiotic recombination process. We demonstrate that the decrease in recombination observed in females homozygous for mcm5(A7) is not due to a failure to create or repair meiotically induced double strand breaks (DSBs), but rather to a failure to resolve those DSBs into meiotic crossovers. Consistent with their ability to repair meiotically induced DSBs, flies homozygous for mcm5(A7) are fully proficient in somatic DNA repair. These results strengthen the observation that members of the prereplicative complex have multiple functions and provide evidence that mcm5 plays a critical role in the meiotic recombination pathway.
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Affiliation(s)
- Cathleen M Lake
- Stowers Institute for Medical Research, 1000 E. 50th Street, Kansas City, MO 64110, USA.
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Nasheuer HP, Pospiech H, Syväoja J. Progress Towards the Anatomy of the Eukaryotic DNA Replication Fork. Genome Integr 2006. [DOI: 10.1007/7050_016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Blanton HL, Radford SJ, McMahan S, Kearney HM, Ibrahim JG, Sekelsky J. REC, Drosophila MCM8, drives formation of meiotic crossovers. PLoS Genet 2006; 1:e40. [PMID: 16189551 PMCID: PMC1231718 DOI: 10.1371/journal.pgen.0010040] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 08/17/2005] [Indexed: 11/19/2022] Open
Abstract
Crossovers ensure the accurate segregation of homologous chromosomes from one another during meiosis. Here, we describe the identity and function of the Drosophila melanogaster gene recombination defective (rec), which is required for most meiotic crossing over. We show that rec encodes a member of the mini-chromosome maintenance (MCM) protein family. Six MCM proteins (MCM2–7) are essential for DNA replication and are found in all eukaryotes. REC is the Drosophila ortholog of the recently identified seventh member of this family, MCM8. Our phylogenetic analysis reveals the existence of yet another family member, MCM9, and shows that MCM8 and MCM9 arose early in eukaryotic evolution, though one or both have been lost in multiple eukaryotic lineages. Drosophila has lost MCM9 but retained MCM8, represented by REC. We used genetic and molecular methods to study the function of REC in meiotic recombination. Epistasis experiments suggest that REC acts after the Rad51 ortholog SPN-A but before the endonuclease MEI-9. Although crossovers are reduced by 95% in rec mutants, the frequency of noncrossover gene conversion is significantly increased. Interestingly, gene conversion tracts in rec mutants are about half the length of tracts in wild-type flies. To account for these phenotypes, we propose that REC facilitates repair synthesis during meiotic recombination. In the absence of REC, synthesis does not proceed far enough to allow formation of an intermediate that can give rise to crossovers, and recombination proceeds via synthesis-dependent strand annealing to generate only noncrossover products. Most of our cells have two copies of each chromosome. For sexual reproduction, these must separate from one another to produce sperm or eggs with one copy of each chromosome. This occurs during meiosis, when chromosomes pair and exchange DNA segments. This exchange— meiotic recombination—creates physical linkages between chromosome pairs and is also a source of genetic diversity. To learn more about the process of meiotic recombination, the authors characterized the gene recombination defective (rec) from the fruit fly Drosophila melanogaster. Molecular analysis revealed that rec is related to a large family of genes found in all animals, plants, and protists. These genes are thought to be important in DNA replication, but rec appears to have a novel function. The authors found that mutants lacking rec are unable to copy enough DNA during meiotic recombination to form linkages between chromosomes. This results in chromosomes segregating randomly during meiosis, so that most eggs have an incorrect number or composition of chromosomes.
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Affiliation(s)
- Hunter L Blanton
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Sarah J Radford
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Susan McMahan
- Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Hutton M Kearney
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Joseph G Ibrahim
- Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Program in Molecular Biology and Biotechnology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
- * To whom correspondence should be addressed. E-mail:
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