Propagation of pSC101 plasmids defective in binding of integration host factor.
Propagation of pSC101 plasmids defective in binding of integration host factor.
复制标题
整合宿主因子结合缺陷的 pSC101 质粒的增殖。
DOI：
10.1128/jb.174.3.785-792.1992
复制
发表时间：
1992
影响因子：
3.2
通讯作者：
Cohen,SN
中科院分区：
文献类型：
--
作者：
Biek,DP;Cohen,SN
整合宿主因子（IHF）是大肠杆菌的一种多功能蛋白，通常是质粒pSC101复制所必需的。T. T. Stenzel， P. Patel和D. Bastia （Cell 49:709- 717,1987）报道IHF结合pSC101复制起点附近的DNA位点，并增强该区域的静态弯曲；IHF结合位点的突变会影响质粒的复制能力。我们在这里报告的研究表明，IHF在pSC101复制起点附近结合的要求部分或完全被以下方式所规避：(i)质粒编码的repA（复制酶）基因或染色体编码的topA基因的突变，（ii） pSC101分割（par）位点的质粒上的存在，或（iii）用强转录启动子取代par位点。除了repA突变外，已知替代功能性起源区IHF结合位点的因子通过增加负DNA超卷曲来改变质粒拓扑结构，IHF本身也是如此。这些结果与IHF结合在pSC101复制起点附近通过诱导构象变化从而形成依赖于repa的dna -蛋白复合物从而促进质粒复制的说法一致。多种与ihf无关的机制可以促进假定的复制起始复合物的形成。
Integration host factor (IHF), a multifunctional protein of E. coli, normally is required for the replication of plasmid pSC101. T. T. Stenzel, P. Patel, and D. Bastia (Cell 49:709-717, 1987) have reported that IHF binds to a DNA locus near the pSC101 replication origin and enhances a static bend present in this region; mutation of the IHF binding site affects the plasmid's ability to replicate. We report here studies indicating that the requirement for IHF binding near the pSC101 replication origin is circumvented partially or completely by (i) mutation of the plasmid-encoded repA (replicase) gene or the chromosomally encoded topA gene, (ii) the presence on the plasmid of the pSC101 partition (par) locus, or (iii) replacement of the par locus by a strong transcriptional promoter. With the exception of the repA mutation, the factors that substitute for a functional origin region IHF binding site are known to alter plasmid topology by increasing negative DNA supercoiling, as does IHF itself. These results are consistent with the proposal that IHF binding near the pSC101 replication origin promotes plasmid replication by inducing a conformational change leading to formation of a repA-dependent DNA-protein complex. A variety of IHF-independent mechanisms can facilitate formation of the putative replication-initiation complex.