Li Y F, Hayashi T, Terawaki Y
Department of Bacteriology, Shinshu University School of Medicine, Matsumoto, Japan.
Plasmid. 1998 Sep;40(2):140-9. doi: 10.1006/plas.1998.1360.
Rts1 RepA and P1 RepA are trans-acting proteins essential for initiation of replication of Rts1 and P1 plasmids, respectively. We recently found that P1 RepA bound in vitro to the Rts1 replication origin as strongly as Rts1 RepA and activated the origin in vivo. However, the ori activation was quite inefficient. This study shows that by replacing a small region of P1 RepA with the corresponding region of Rts1 RepA, the efficiency of Rts1 ori activation increased markedly. Interestingly, the same subregion of P1 RepA was found to be important for in vivo activation of the P1 origin. Thus, a region essential for efficient activation of the replication origin was assigned to the P1 RepA molecule as well as to the Rts1 RepA molecule. The region was distinct from a domain necessary for in vitro binding to the origin, although both regions were required for in vivo activation of the respective origin.
Rts1 RepA和P1 RepA分别是Rts1和P1质粒复制起始所必需的反式作用蛋白。我们最近发现，P1 RepA在体外与Rts1复制起点的结合强度与Rts1 RepA相同，并在体内激活该起点。然而，ori激活效率相当低。本研究表明，通过用Rts1 RepA的相应区域替换P1 RepA的一个小区域，Rts1 ori激活效率显著提高。有趣的是，发现P1 RepA的同一亚区域对P1起点的体内激活很重要。因此，一个对复制起点高效激活必不可少的区域被确定为P1 RepA分子以及Rts1 RepA分子所共有。该区域与体外结合起点所需的结构域不同，尽管这两个区域对于各自起点的体内激活都是必需的。
