Malone R E, Ward T, Lin S, Waring J
Department of Biology, University of Iowa, Iowa City 52242.
Curr Genet. 1990 Aug;18(2):111-6. doi: 10.1007/BF00312598.
Mutations in the RAD50 gene of Saccharomyces cerevisiae have been shown to reduce double strand break repair, meiotic recombination, and radiation-inducible mitotic recombination. Several different point mutations (including ochre and amber alleles) have been previously examined for effects on spontaneous mitotic recombination and did not reduce the frequency of recombination. Instead, the rad50 mutations conferred a moderate hyper-rec phenotype. This paper examines a deletion/interruption allele of RAD50 that removes 998 of 1312 amino acids and adds 1.1 kb of foreign DNA. The results clearly indicate that spontaneous mitotic recombination can occur in the absence of RAD50; in fact, the frequency of recombination is elevated over the wild-type cell. One possible interpretation of these observations is that the initiating lesion in spontaneous recombination events in mitosis might not be a double strand break.
酿酒酵母RAD50基因的突变已被证明会降低双链断裂修复、减数分裂重组和辐射诱导的有丝分裂重组。先前已检测了几种不同的点突变（包括赭石型和琥珀型等位基因）对自发有丝分裂重组的影响，这些突变并未降低重组频率。相反，rad50突变赋予了中等程度的高重组表型。本文研究了RAD50的一个缺失/中断等位基因，该等位基因去除了1312个氨基酸中的998个，并添加了1.1 kb的外源DNA。结果清楚地表明，在没有RAD50的情况下也能发生自发有丝分裂重组；事实上，重组频率比野生型细胞有所提高。对这些观察结果的一种可能解释是，有丝分裂中自发重组事件的起始损伤可能不是双链断裂。
