Kato J, Nishimura Y, Imamura R, Niki H, Hiraga S, Suzuki H
Department of Bacteriology, National Institute of Health of Japan, Tokyo.
Cell. 1990 Oct 19;63(2):393-404. doi: 10.1016/0092-8674(90)90172-b.
The nucleotide sequence of the parC gene essential for chromosome partition in E. coli was determined. The deduced amino acid sequence was homologous to that of the A subunit of gyrase. We found another new gene coding for about 70 kd protein. The gene was sequenced, and the deduced amino acid sequence revealed that the gene product was homologous to the gyrase B subunit. Mutants of this gene were isolated and showed the typical Par phenotype at nonpermissive temperature; thus the gene was named parE. Enhanced relaxation activity of supercoiled plasmid molecules was detected in the combined crude cell lysates prepared from the ParC and ParE overproducers. A topA mutation defective in topoisomerase I could be compensated by increasing both the parC and the parE gene dosage. It is suggested that the parC and parE genes code for the subunits of a new topoisomerase, named topo IV.
测定了大肠杆菌中染色体分配所必需的parC基因的核苷酸序列。推导的氨基酸序列与促旋酶A亚基的序列同源。我们发现了另一个编码约70kd蛋白质的新基因。对该基因进行了测序，推导的氨基酸序列表明该基因产物与促旋酶B亚基同源。分离出该基因的突变体，其在非允许温度下表现出典型的Par表型；因此该基因被命名为parE。在由ParC和ParE过量表达菌株制备的混合粗细胞裂解物中检测到超螺旋质粒分子的增强的松弛活性。拓扑异构酶I缺陷的topA突变可通过增加parC和parE基因剂量来补偿。提示parC和parE基因编码一种名为拓扑异构酶IV的新拓扑异构酶的亚基。
