Chen W, Jinks-Robertson S
Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia 30322, USA.
Genetics. 1999 Apr;151(4):1299-313. doi: 10.1093/genetics/151.4.1299.
Nonidentical recombination substrates recombine less efficiently than do identical substrates in yeast, and much of this inhibition can be attributed to action of the mismatch repair (MMR) machinery. In this study an intron-based inverted repeat assay system has been used to directly compare the rates of mitotic and meiotic recombination between pairs of 350-bp substrates varying from 82% to 100% in sequence identity. The recombination rate data indicate that sequence divergence impacts mitotic and meiotic recombination similarly, although subtle differences are evident. In addition to assessing recombination rates as a function of sequence divergence, the endpoints of mitotic and meiotic recombination events involving 94%-identical substrates were determined by DNA sequencing. The endpoint analysis indicates that the extent of meiotic heteroduplex DNA formed in a MMR-defective strain is 65% longer than that formed in a wild-type strain. These data are consistent with a model in which the MMR machinery interferes with the formation and/or extension of heteroduplex intermediates during recombination.
在酵母中，非同源重组底物的重组效率低于同源底物，这种抑制作用很大程度上可归因于错配修复（MMR）机制的作用。在本研究中，基于内含子的反向重复检测系统被用于直接比较序列同一性从82%到100%不等的350bp底物对之间的有丝分裂和减数分裂重组率。重组率数据表明，序列差异对有丝分裂和减数分裂重组的影响相似，尽管存在细微差异。除了评估重组率作为序列差异的函数外，还通过DNA测序确定了涉及94%同一性底物的有丝分裂和减数分裂重组事件的终点。终点分析表明，在MMR缺陷菌株中形成的减数分裂异源双链DNA的长度比在野生型菌株中形成的长65%。这些数据与一个模型一致，即在重组过程中，MMR机制会干扰异源双链中间体的形成和/或延伸。
