Kobayashi T, Hidaka M, Horiuchi T
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
EMBO J. 1989 Aug;8(8):2435-41. doi: 10.1002/j.1460-2075.1989.tb08374.x.
Activity binding specifically to the 22 bp of the DNA replication terminus (ter) sequence on plasmid R6K and the Escherichia coli genome was detected in the crude extract of E. coli cells. This activity was inactivated by heat or by protease but not by RNase treatments. Overproduction of the ter binding activity was observed when the extract was prepared from the cell carrying a plasmid with a chromosomal-derived 5.0 kb EcoRI fragment, on which one of the four terC sites, terC2, was also located. By mutagenesis of the 5.0 kb fragment on the plasmid with transposon Tn3 and subsequent replacement of the corresponding chromosomal region with the resulting mutant alleles, we isolated tau- mutants completely defective in ter binding activity. These mutants simultaneously lost the activity to block the progress of the DNA replication fork at any ter site, on the genome or the plasmid. It would thus appear that the ter binding protein plays an essential role in the termination reaction, at the ter sites.
在大肠杆菌细胞的粗提物中检测到了与质粒R6K及大肠杆菌基因组上DNA复制终点（ter）序列的22个碱基对特异性结合的活性。该活性可被加热或蛋白酶灭活，但不能被RNA酶处理灭活。当从携带一个带有染色体来源的5.0 kb EcoRI片段的质粒的细胞中制备提取物时，观察到ter结合活性过量产生，该片段上四个terC位点之一terC2也位于其上。通过用转座子Tn3对质粒上的5.0 kb片段进行诱变，并随后用产生的突变等位基因替换相应的染色体区域，我们分离出了在ter结合活性方面完全缺陷的tau-突变体。这些突变体同时丧失了在基因组或质粒上的任何ter位点处阻断DNA复制叉前进的活性。因此，ter结合蛋白似乎在ter位点的终止反应中起重要作用。
