Molecular structures of crossover and noncrossover intermediates during gap repair in yeast: implications for recombination.
The molecular structures of crossover (CO) and noncrossover (NCO) intermediates were determined by sequencing the products formed when a gapped plasmid was repaired using a diverged chromosomal template. Analyses were done in the absence of mismatch repair (MMR) to allow efficient detection of strand-transfer intermediates, and the results reveal striking differences in the extents and locations of heteroduplex DNA (hDNA) in NCO versus CO products. These data indicate that most NCOs are produced by synthesis-dependent strand annealing rather than by a canonical double-strand break repair pathway and that resolution of Holliday junctions formed as part of the latter pathway is highly constrained to generate CO products. We suggest a model in which the length of hDNA formed by the initiating strand invasion event determines susceptibility of the resulting intermediate to antirecombination and ultimately whether a CO- or a NCO-producing pathway is followed.
Mitchel
Katrina
K
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
Zhang
Hengshan
H
Welz-Voegele
Caroline
C
Jinks-Robertson
Sue
S
D015825:Chromosomes, Fungal / Q000235:genetics; D003434:Crossing Over, Genetic; D004260:DNA Repair / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics*; D008957:Models, Genetic; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D004271:DNA, Fungal; D009692:Nucleic Acid Heteroduplexes