Reduced mismatch repair of heteroduplexes reveals "non"-interfering crossing over in wild-type Saccharomyces cerevisiae.
Using small palindromes to monitor meiotic double-strand-break-repair (DSBr) events, we demonstrate that two distinct classes of crossovers occur during meiosis in wild-type yeast. We found that crossovers accompanying 5:3 segregation of a palindrome show no conventional (i.e., positive) interference, while crossovers with 6:2 or normal 4:4 segregation for the same palindrome, in the same cross, do manifest interference. Our observations support the concept of a "non"-interference class and an interference class of meiotic double-strand-break-repair events, each with its own rules for mismatch repair of heteroduplexes. We further show that deletion of MSH4 reduces crossover tetrads with 6:2 or normal 4:4 segregation more than it does those with 5:3 segregation, consistent with Msh4p specifically promoting formation of crossovers in the interference class. Additionally, we present evidence that an ndj1 mutation causes a shift of noncrossovers to crossovers specifically within the "non"-interference class of DSBr events. We use these and other data in support of a model in which meiotic recombination occurs in two phases-one specializing in homolog pairing, the other in disjunction-and each producing both noncrossovers and crossovers.
Getz
Tony J
TJ
Department of Biology, University of Oregon, Eugene, Oregon 97403-1229, USA.
Banse
Stephen A
SA
Young
Lisa S
LS
Banse
Allison V
AV
Swanson
Johanna
J
Wang
Grace M
GM
Browne
Barclay L
BL
Foss
Henriette M
HM
Stahl
Franklin W
FW
D002874:Chromosome Mapping; D020090:Chromosome Segregation; D003434:Crossing Over, Genetic / Q000235:genetics*; D053843:DNA Mismatch Repair; D004171:Diploidy; D017353:Gene Deletion; D005819:Genetic Markers; D008957:Models, Genetic; D009692:Nucleic Acid Heteroduplexes / Q000378:metabolism*; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism
D005819:Genetic Markers; D009692:Nucleic Acid Heteroduplexes; D029701:Saccharomyces cerevisiae Proteins