Rsp5, a Ubiquitin-Protein Ligase, Is Involved in Degradation of the Single-Stranded-DNA Binding Protein Rfa1 in Saccharomyces cerevisiae
AUTOR(ES)
Erdeniz, Naz
FONTE
American Society for Microbiology
RESUMO
In Saccharomyces cerevisiae, RAD1 and RAD52 are required for alternate pathways of mitotic recombination. Double-mutant strains exhibit a synergistic interaction that decreases direct repeat recombination rates dramatically. A mutation in RFA1, the largest subunit of a single-stranded DNA-binding protein complex (RP-A), suppresses the recombination deficiency of rad1 rad52 strains (J. Smith and R. Rothstein, Mol. Cell. Biol. 15:1632–1641, 1995). Previously, we hypothesized that this mutation, rfa1-D228Y, causes an increase in recombinogenic lesions as well as the activation of a RAD52-independent recombination pathway. To identify gene(s) acting in this pathway, temperature-sensitive (ts) mutations were screened for those that decrease recombination levels in a rad1 rad52 rfa1-D228Y strain. Three mutants were isolated. Each segregates as a single recessive gene. Two are allelic to RSP5, which encodes an essential ubiquitin-protein ligase. One allele, rsp5-25, contains two mutations within its open reading frame. The first mutation does not alter the amino acid sequence of Rsp5, but it decreases the amount of full-length protein in vivo. The second mutation results in the substitution of a tryptophan with a leucine residue in the ubiquitination domain. In rsp5-25 mutants, the UV sensitivity of rfa1-D228Y is suppressed to the same level as in strains overexpressing Rfa1-D228Y. Measurement of the relative rate of protein turnover demonstrated that the half-life of Rfa1-D228Y in rsp5-25 mutants was extended to 65 min compared to a 35-min half-life in wild-type strains. We propose that Rsp5 is involved in the degradation of Rfa1 linking ubiquitination with the replication-recombination machinery.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=85078Documentos Relacionados
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