title: Sgs1 function in the repair of DNA replication intermediates is separable from its role in homologous recombinational repair.
abstract: Mutations in human homologues of the bacterial RecQ helicase cause diseases leading to cancer predisposition and/or shortened lifespan (Werner, Bloom, and Rothmund-Thomson syndromes). The budding yeast Saccharomyces cerevisiae has one RecQ helicase, Sgs1, which functions with Top3 and Rmi1 in DNA repair. Here, we report separation-of-function alleles of SGS1 that suppress the slow growth of top3Delta and rmi1Delta cells similar to an SGS1 deletion, but are resistant to DNA damage similar to wild-type SGS1. In one allele, the second acidic region is deleted, and in the other, only a single aspartic acid residue 664 is deleted. sgs1-D664Delta, unlike sgs1Delta, neither disrupts DNA recombination nor has synthetic growth defects when combined with DNA repair mutants. However, during S phase, it accumulates replication-associated X-shaped structures at damaged replication forks. Furthermore, fluorescent microscopy reveals that the sgs1-D664Delta allele exhibits increased spontaneous RPA foci, suggesting that the persistent X-structures may contain single-stranded DNA. Taken together, these results suggest that the Sgs1 function in repair of DNA replication intermediates can be uncoupled from its role in homologous recombinational repair.
authors.affiliation: Department of Genetics & Development, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Kara A
authors.initials: KA
authors.lastname: Bernstein
authors.forename: Erika
authors.initials: E
authors.lastname: Shor
authors.forename: Ivana
authors.initials: I
authors.lastname: Sunjevaric
authors.forename: Marco
authors.initials: M
authors.lastname: Fumasoni
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Burgess
authors.forename: Marco
authors.initials: M
authors.lastname: Foiani
authors.forename: Dana
authors.initials: D
authors.lastname: Branzei
authors.forename: Rodney
authors.initials: R
authors.lastname: Rothstein
mesh_terms: D004260:DNA Repair / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology*; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009154:Mutation; D010641:Phenotype; D053484:RecQ Helicases / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic; D051716:Replication Protein A; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; C082728:RFA1 protein, S cerevisiae; D051716:Replication Protein A; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C090472:SGS1 protein, S cerevisiae; D053484:RecQ Helicases