title: Yeast Rad55 and Rad57 proteins form a heterodimer that functions with replication protein A to promote DNA strand exchange by Rad51 recombinase.
abstract: Saccharomyces cerevisiae RAD51, RAD55, and RAD57 genes, required for genetic recombination and DNA double-strand-break repair, encode proteins homologous to one another and to the Escherichia coli RecA protein. Rad51 protein catalyzes the DNA strand-exchange reaction with a dependence on ATP and on the heterotrimeric single-strand DNA (ssDNA) binding factor replication protein A (RPA). By several independent criteria, RAD55- and RAD57-encoded products are shown here to exist as a stable heterodimer, with a dissociation constant of <2 x 10(-10) M. In strand exchange, the reaction proceeds efficiently if RPA is incorporated after nucleation of Rad51 onto ssDNA, but if RPA is present during the nucleation phase, as is likely the case in vivo, the amount of strand-exchange products becomes relatively insignificant. Inclusion of the Rad55-Rad57 heterodimer with Rad51 and RPA results in a marked stimulation of strand exchange, providing evidence for a role of the Rad55-Rad57 heterodimer in overcoming the inhibitory effect of RPA.
authors.affiliation: Sealy Center for Molecular Science, University of Texas Medical Branch at Galveston, 77555-1061, USA. sung@uthscsa.edu
authors.forename: P
authors.initials: P
authors.lastname: Sung
mesh_terms: D000251:Adenosine Triphosphatases; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004271:DNA, Fungal / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D019426:Integrases; D051135:Rad51 Recombinase; D011938:Rec A Recombinases / Q000378:metabolism; D045522:Recombinases; D011995:Recombination, Genetic; D051716:Replication Protein A; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D004271:DNA, Fungal; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C087191:RAD55 protein, S cerevisiae; D045522:Recombinases; D051716:Replication Protein A; D029701:Saccharomyces cerevisiae Proteins; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; D011938:Rec A Recombinases; C115006:integron integrase IntI1; D000251:Adenosine Triphosphatases; C071451:RAD57 protein, S cerevisiae; D045643:DNA Repair Enzymes