title: Meiotic recombination initiated by a double-strand break in rad50 delta yeast cells otherwise unable to initiate meiotic recombination.
abstract: Meiotic recombination in Saccharomyces cerevisiae is initiated by double- strand breaks (DSBs). We have developed a system to compare the properties of meiotic DSBs with those created by the site-specific HO endonuclease. HO endonuclease was expressed under the control of the meiotic-specific SPO13 promoter, creating a DSB at a single site on one of yeast's 16 chromosomes. In Rad+ strains the times of appearance of the HO-induced DSBs and of subsequent recombinants are coincident with those induced by normal meiotic DSBs. Physical monitoring of DNA showed that SPO13: : HO induced gene conversions both in Rad+ and in rad50 delta cells that cannot initiate normal meiotic DSBs. We find that the RAD50 gene is important, but not essential, for recombination even after a DSB has been created in a meiotic cell. In rad50 delta cells, some DSBs are not repaired until a broken chromosome has been packaged into a spore and is subsequently germinated. This suggests that a broken chromosome does not signal an arrest of progression through meiosis. The recombination defect in rad50 delta diploids is not, however, meiotic specific, as mitotic rad50 diploids, experiencing an HO-induced DSB, exhibit similar departures from wild-type recombination.
authors.affiliation: Rosenstiel Center, Brandeis University, Waltham, Massachusetts 02254-9110, USA.
authors.forename: A
authors.initials: A
authors.lastname: Malkova
authors.forename: L
authors.initials: L
authors.lastname: Ross
authors.forename: D
authors.initials: D
authors.lastname: Dawson
authors.forename: M F
authors.initials: MF
authors.lastname: Hoekstra
authors.forename: J E
authors.initials: JE
authors.lastname: Haber
mesh_terms: D004271:DNA, Fungal / Q000235:genetics*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics*; D008540:Meiosis / Q000235:genetics*; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D004271:DNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; C530845:HO protein, S cerevisiae; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific