Sharples G J, Lloyd R G
Department of Genetics, University of Nottingham, Queens Medical Centre, UK.
Nucleic Acids Res. 1993 Jul 25;21(15):3359-64. doi: 10.1093/nar/21.15.3359.
Escherichia coli RuvC protein is a specific endonuclease that resolves recombination intermediates into viable products. The structural features needed for RuvC activity were investigated by sequencing three ruvC mutations and relating the base pair changes identified to the activity of the mutant proteins. Each of the three mutations is a single base-pair substitution. ruvC51 converts glycine-15 to an aspartic acid residue. The product of ruvC51 was purified and shown to retain the ability to bind junctions, albeit with a slightly reduced affinity. However, it has lost the ability to resolve these structures by symmetrical cleavage. A multicopy ruvC51 plasmid confers sensitivity to UV light in a ruvC+ strain. The ruvC53 allele causes a glycine-17 to serine substitution while ruvC55 produces a stop codon. Neither of these genes produces a stable product. The results suggest that the N-terminal domain of RuvC may be concerned with cleavage of junctions.
大肠杆菌RuvC蛋白是一种特异性核酸内切酶，可将重组中间体分解为有活性的产物。通过对三个ruvC突变进行测序，并将鉴定出的碱基对变化与突变蛋白的活性相关联，研究了RuvC活性所需的结构特征。这三个突变均为单碱基对替换。ruvC51将甘氨酸-15转化为天冬氨酸残基。ruvC51的产物被纯化，并显示出保留结合连接点的能力，尽管亲和力略有降低。然而，它已失去通过对称切割分解这些结构的能力。多拷贝ruvC51质粒在ruvC+菌株中赋予对紫外线的敏感性。ruvC53等位基因导致甘氨酸-17被丝氨酸取代，而ruvC55产生一个终止密码子。这两个基因均不产生稳定的产物。结果表明，RuvC的N端结构域可能与连接点的切割有关。
