Effects of the chromosome partitioning protein Spo0J (ParB) on oriC of positioning and replication initiation Bacillus subtilis
Effects of the chromosome partitioning protein Spo0J (ParB) on oriC of positioning and replication initiation Bacillus subtilis
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DOI：
10.1128/jb.185.4.1326-1337.2003
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发表时间：
2003-02-01
影响因子：
3.2
通讯作者：
Grossman, AD
中科院分区：
文献类型：
--
作者：
Lee, PS;Lin, DCH;Grossman, AD
枯草芽孢杆菌的Spo 0 J [阿里斯]是一种DNA结合蛋白，属于许多细菌物种中有效质粒和染色体分配所需的保守蛋白质家族。我们发现Spo 0 J有助于定位染色体oriC区域，但可能不是通过将起源区域招募到特定的亚细胞位置。在指数生长期间的野生型细胞中，复制的起源区域通常位于细胞区周围。在spo 0 J无效突变体中，姐妹起源区域通常更靠近中间细胞。我们发现，通过使用Spo 0 J-绿色荧光蛋白[GFP]融合，Spo 0 J的亚细胞位置是Spo 0 J结合位点的染色体位置的结果。当在八个已知parS位点中的六个不存在的情况下将一系列结合位点（parS位点）插入到不同的染色体位置时，Spo 0 J-GFP不再主要存在于细胞区，表明Spo 0 J不足以将染色体parS位点募集到细胞区。spo 0 J也影响孢子形成过程中染色体的定位。一个spo 0 J无效突变体表现出一些位于前孢子的起源远端区域的细胞数量增加。此外，spo 0 J无效突变导致每个细胞的LacI-GFP结合到插入在染色体中的各个位置（包括起源区域）的lac操纵子阵列的焦点数目增加，DNA-蛋白质比率增加，以及每个细胞的起源增加，如通过流式细胞术所确定的。这些结果表明，spo 0 J突变体产生了显着比例的细胞染色体含量增加，可能是由于增加和异步启动的DNA复制。
Spo0J [P aris] of Bacillus subtilis is a DNA-binding protein that belongs to a conserved family of proteins required for efficient plasmid and chromosome partitioning in many bacterial species. We found that Spo0J contributes to the positioning of the chromosomal oriC region, but probably not by recruiting the origin regions to specific subcellular locations. In wild-type cells during exponential growth, duplicated origin regions were generally positioned around the cell quarters. In a spo0J null mutant, sister origin regions were often closer together, nearer to midcell. We found, by using a Spo0J-green fluorescent protein [GFP] fusion, that the subcellular location of Spo0J was a consequence of the chromosomal positions of the Spo0J binding sites. When an array of binding sites (parS sites) were inserted at various chromosomal locations in the absence of six of the eight known parS sites, Spo0J-GFP was no longer found predominantly at the cell quarters, indicating that Spo0J is not sufficient to recruit chromosomal parS sites to the cell quarters. spo0J also affected chromosome positioning during sporulation. A spo0J null mutant showed an increase in the number of cells with some origin-distal regions located in the forespore. In addition, a spo0J null mutation caused an increase in the number of foci per cell of LacI-GFP bound to arrays of lac operators inserted in various positions in the chromosome, including the origin region, an increase in the DNA-protein ratio, and an increase in origins per cell, as determined by flow cytometry. These results indicate that the spo0J mutant produced a significant proportion of cells with increased chromosome content, probably due to increased and asynchronous initiation of DNA replication.