Manivasakam P, Rosenberg S M, Hastings P J
Department of Genetics, University of Alberta, Edmonton, Canada.
Genetics. 1996 Feb;142(2):407-16. doi: 10.1093/genetics/142.2.407.
In yeast meiotic recombination, alleles used as genetic markers fall into two classes as regards their fate when incorporated into heteroduplex DNA. Normal alleles are those that form heteroduplexes that are nearly always recognized and corrected by the mismatch repair system operating in meiosis. High PMS (postmeiotic segregation) alleles form heteroduplexes that are inefficiently mismatch repaired. We report that placing any of several high PMS alleles very close to normal alleles causes hyperrecombination between these markers. We propose that this hyperrecombination is caused by the high PMS allele blocking a mismatch repair tract initiated from the normal allele, thus preventing corepair of the two alleles, which would prevent formation of recombinants. The results of three point crosses involving two PMS alleles and a normal allele suggest that high PMS alleles placed between two alleles that are normally corepaired block that corepair.
在酵母减数分裂重组过程中，用作遗传标记的等位基因在整合到异源双链DNA中时，就其命运而言可分为两类。正常等位基因形成的异源双链几乎总是被减数分裂中起作用的错配修复系统识别并校正。高PMS（减数分裂后分离）等位基因形成的异源双链进行错配修复的效率较低。我们报告称，将几个高PMS等位基因中的任何一个置于非常靠近正常等位基因的位置，会导致这些标记之间发生超重组。我们提出，这种超重组是由高PMS等位基因阻断从正常等位基因起始的错配修复途径引起的，从而阻止了两个等位基因的共修复，而这会阻止重组体的形成。涉及两个PMS等位基因和一个正常等位基因的三点杂交结果表明，置于通常会进行共修复的两个等位基因之间的高PMS等位基因会阻断这种共修复。
