title: Novel essential DNA repair proteins Nse1 and Nse2 are subunits of the fission yeast Smc5-Smc6 complex.
abstract: The structural maintenance of chromosomes (SMC) family of proteins play essential roles in genomic stability. SMC heterodimers are required for sister-chromatid cohesion (Cohesin: Smc1 & Smc3), chromatin condensation (Condensin: Smc2 & Smc4), and DNA repair (Smc5 & Smc6). The SMC heterodimers do not function alone and must associate with essential non-SMC subunits. To gain further insight into the essential and DNA repair roles of the Smc5-6 complex, we have purified fission yeast Smc5 and identified by mass spectrometry the co-precipitating proteins, Nse1 and Nse2. We show that both Nse1 and Nse2 interact with Smc5 in vivo, as part of the Smc5-6 complex. Nse1 and Nse2 are essential proteins and conserved from yeast to man. Loss of Nse1 and Nse2 function leads to strikingly similar terminal phenotypes to those observed for Smc5-6 inactivation. In addition, cells expressing hypomorphic alleles of Nse1 and Nse2 are, like Smc5-6 mutants, hypersensitive to DNA damage. Epistasis analysis suggests that like Smc5-6, Nse1, and Nse2 function together with Rhp51 in the homologous recombination repair of DNA double strand breaks. The results of this study strongly suggest that Nse1 and Nse2 are novel non-SMC subunits of the fission yeast Smc5-6 DNA repair complex.
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
authors.forename: W Hayes
authors.initials: WH
authors.lastname: McDonald
authors.forename: Yelena
authors.initials: Y
authors.lastname: Pavlova
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: Michael N
authors.initials: MN
authors.lastname: Boddy
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry*; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D002850:Chromatography, Gel; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000502:physiology; D019281:Dimerization; D004307:Dose-Response Relationship, Radiation; D017353:Gene Deletion; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010641:Phenotype; D051135:Rad51 Recombinase; D011995:Recombination, Genetic; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D012568:Schizosaccharomyces; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; C460369:NSE1 protein, S cerevisiae; C479823:Nse2 protein, S pombe; D009687:Nuclear Proteins; D010455:Peptides; C084232:RHP51 protein, S pombe; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C486628:Smc5 protein, S pombe; C486630:smc6 protein, S pombe; D051135:Rad51 Recombinase