title: Tid1/Rdh54 promotes colocalization of rad51 and dmc1 during meiotic recombination.
abstract: Two RecA homologs, Rad51 and Dmc1, assemble as cytologically visible complexes (foci) at the same sites on meiotic chromosomes. Time course analysis confirms that co-foci appear and disappear as the single predominant form. A large fraction of co-foci are eliminated in a red1 mutant, which is expected as a characteristic of the interhomolog-specific recombination pathway. Previous studies suggested that normal Dmc1 loading depends on Rad51. We show here that a mutation in TID1/RDH54, encoding a RAD54 homolog, reduces Rad51-Dmc1 colocalization relative to WT. A rad54 mutation, in contrast, has relatively little effect on RecA homolog foci except when strains also contain a tid1/rdh54 mutation. The role of Tid1/Rdh54 in coordinating RecA homolog assembly may be very direct, because Tid1/Rdh54 is known to physically bind both Dmc1 and Rad51. Also, Dmc1 foci appear early in a tid1/rdh54 mutant. Thus, Tid1 may normally act with Rad51 to promote ordered RecA homolog assembly by blocking Dmc1 until Rad51 is present. Finally, whereas double-staining foci predominate in WT nuclei, a subset of nuclei with expanded chromatin exhibit individual Rad51 and Dmc1 foci side-by-side, suggesting that a Rad51 homo-oligomer and a Dmc1 homo-oligomer assemble next to one another at the site of a single double-strand break (DSB) recombination intermediate.
authors.affiliation: Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyma, Toyonaka, Osaka 560-0043, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Shinohara
authors.forename: S L
authors.initials: SL
authors.lastname: Gasior
authors.forename: D K
authors.initials: DK
authors.lastname: Bishop
authors.forename: A
authors.initials: A
authors.lastname: Shinohara
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins; D004265:DNA Helicases; D045643:DNA Repair Enzymes; D026942:DNA Topoisomerases; D004268:DNA-Binding Proteins / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D006168:Guinea Pigs; D008540:Meiosis / Q000235:genetics*; D051135:Rad51 Recombinase; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D018797:Cell Cycle Proteins; C513033:DMC1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase; C075468:RAD54 protein, S cerevisiae; D004265:DNA Helicases; D026942:DNA Topoisomerases; C541336:RDH54 protein, S cerevisiae; D045643:DNA Repair Enzymes