The efficiency of meiotic recombination between dispersed sequences in Saccharomyces cerevisiae depends upon their chromosomal location.
To examine constrains imposed on meiotic recombination by homologue pairing, we measured the frequency of recombination between mutant alleles of the ARG4 gene contained in pBR322-based inserts. Inserts were located at identical loci on homologues (allelic recombination) or at different loci on either homologous or heterologous chromosomes (ectopic recombination). Ectopic recombination between interstitially located inserts on heterologous chromosomes had an efficiency of 6-12% compared to allelic recombination. By contrast, ectopic recombination between interstitial inserts located on homologues had relative efficiencies of 47-99%. These findings suggest that when meiotic ectopic recombination occurs, homologous chromosomes are already colocalized. The efficiency of ectopic recombination between inserts on homologues decreased as the physical distance between insert sites was increased. This result is consistent with the suggestion that during meiotic recombination, homologues are not only close to each other, but also are aligned end to end. Finally, the efficiency of ectopic recombination between inserts near telomeres (within 16 kb) was significantly greater than that observed with inserts > 50 kb from the nearest telomere. Thus, at the time of recombination, there may be a special relationship between the ends of chromosomes not shared with interstitial regions.
Goldman
A S
AS
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. goldman@sunspot.nci.nih.gov
Lichten
M
M
D001123:Argininosuccinate Lyase; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D005656:Fungal Proteins / Q000235:genetics*; D008432:Mathematical Computing; D008957:Models, Genetic; D016254:Mutagenesis, Insertional; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C087900:Arg4 protein, S cerevisiae; D001123:Argininosuccinate Lyase