THE P1 PLASMID-PARTITION SYSTEM SYNTHESIZES 2 ESSENTIAL PROTEINS FROM AN AUTOREGULATED OPERON
THE P1 PLASMID-PARTITION SYSTEM SYNTHESIZES 2 ESSENTIAL PROTEINS FROM AN AUTOREGULATED OPERON
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DOI：
10.1016/0147-619x(88)90049-2
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发表时间：
1988-03-01
期刊：
影响因子：
2.6
通讯作者：
AUSTIN, SJ
中科院分区：
文献类型：
--
作者：
FRIEDMAN, SA;AUSTIN, SJ
P1分割区包含两个大的开放阅读框，编码蛋白ParA和ParB。先前的研究表明，ParA对分区活动至关重要。使用一种新的分析方法，我们发现ParB蛋白也是分割的绝对需要，并且它在转化到分割质粒中是活跃的。parA和parB的互补测试的发展使我们能够将P1微质粒的一些分裂缺陷点突变分配到parA和parB顺子上。利用基因融合技术，发现parA和parB构成了一个由parA近端启动子控制的操纵子。该启动子的转录由一个对ParA和ParB蛋白一致敏感的反馈回路自动调节。parB基因似乎也从顺子间边界的第二个启动子低水平表达。这导致ParA蛋白的低水平表达和严格的自动调节，而对ParB合成的控制略不严格。
The P1 partition region contains two large open reading frames that encode the proteins ParA and ParB. It was previously shown that ParA is essential for partition activity. Using a novel assay, we show that ParB protein is also an absolute requirement for partition and that it is active in trans to the partitioning plasmid. Development of complementation tests for parA and parB allowed us to assign a number of partition-defective point mutants of a P1 miniplasmid to the parA and parB cistrons. Using gene fusion techniques, it was shown that parA and parB constitute an operon controlled from a promoter proximal to the start of parA. Transcription from this promoter is autoregulated by a feedback loop that is sensitive to the ParA and ParB proteins in concert. The parB gene also appears to be expressed at a low level from a second promoter at the intercistronic boundary. This results in a low level of expression and tight autoregulation for the ParA protein and slightly less stringent control for ParB synthesis.