title: Smc5p promotes faithful chromosome transmission and DNA repair in Saccharomyces cerevisiae.
abstract: Heterodimers of structural maintenance of chromosomes (SMC) proteins form the core of several protein complexes involved in the organization of DNA, including condensation and cohesion of the chromosomes at metaphase. The functions of the complexes with a heterodimer of Smc5p and Smc6p are less clear. To better understand them, we created two S. cerevisiae strains bearing temperature-sensitive alleles of SMC5. When shifted to the restrictive temperature, both mutants lose viability gradually, concomitant with the appearance of nuclear abnormalities and phosphorylation of the Rad53p DNA damage checkpoint protein. Removal of Rad52p or overexpression of the SUMO ligase Mms21p partially suppresses the temperature sensitivity of smc5 strains and increases their survival at the restrictive temperature. At the permissive temperature, smc5-31 but not smc5-33 cells exhibit hypersensitivity to several DNA-damaging agents despite induction of the DNA damage checkpoint. Similarly, smc5-31 but not smc5-33 cells are killed by overexpression of the SUMO ligase-defective Mms21-SAp but not by overexpression of wild-type Mms21p. Both smc5 alleles are synthetically lethal with mms21-SA and exhibit Rad52p-independent chromosome fragmentation and loss at semipermissive temperatures. Our data indicate a critical role for the S. cerevisiae Smc5/6-containing complexes in both DNA repair and chromosome segregation.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Cost
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Cozzarelli
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D064447:Checkpoint Kinase 2; D004260:DNA Repair; D019281:Dimerization; D015966:Gene Expression Regulation, Fungal; D008957:Models, Genetic; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051721:Rad52 DNA Repair and Recombination Protein / Q000378:metabolism; D025842:SUMO-1 Protein / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; C500948:Mms21 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; C486627:SMC5 protein, S cerevisiae; C486631:SMC6 protein, S cerevisiae; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae