Regulation of the pAD1-encoded sex pheromone response in Enterococcus faecalis: expression of the positive regulator TraE1.
Regulation of the pAD1-encoded sex pheromone response in Enterococcus faecalis: expression of the positive regulator TraE1.
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粪肠球菌中 pAD1 编码的性信息素反应的调节：正调节因子 TraE1 的表达。
DOI：
10.1128/jb.175.4.1008-1018.1993
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发表时间：
1993
影响因子：
3.2
通讯作者：
Clewell,DB
中科院分区：
文献类型：
--
作者：
Tanimoto,K;Clewell,DB
pAD1 是粪肠球菌中的一种 60 kb 溶血素-细菌素接合质粒，编码对潜在受体细菌分泌的小肽性信息素 cAD1 的交配反应。该反应由一组基因调节，其中包括正调控决定簇 traE1，能够激活接合过程中涉及的关键结构基因。负调控决定子 traA 影响 traE1 的表达，并且对信息素信号敏感。两个决定簇之间有一个基因 iad，它编码一个小肽 iAD1，它是 cAD1 的竞争性抑制剂。决定簇 (traE1-iad-traA) 的方向使得 iad 和 traE1 以相同方向转录，与 traA 方向相反。 iad 和 traA 的转录在这些决定因素之间开始，并在每种情况下向外移动。我们实验室最近的一份关于 traE1-iad 区域转录融合的报告（L. T. Pontius 和 D. B. Clewell, J. Bacteriol. 174:3152-3160, 1992）表明 traE1 表达可能依赖于 iad 和 traE1 之间终止子的转录通读。本报告提供了诱导前和诱导期间相关 RNA 种类的直接分析，并表明 iad 的转录通读确实在 traE1 的初始表达中很重要。然而，数据显示，一旦traE1被激活，它就可以独立表达，可能是因为TraE1激活了自己的启动子。这一观点也得到了遗传互补研究的支持。此外，TraA 的 DNA 结合研究表明该蛋白与 iad 的启动子结合。无法检测到 TraA 与 iad 和 traE1 之间区域的结合；然而，仍然不排除 TraA 参与影响该区域转录终止的可能性，因为可能涉及其他因素。提出了信息素反应调节模型。
pAD1 is a conjugative, 60-kb, hemolysin-bacteriocin plasmid in Enterococcus faecalis that encodes a mating response to a small peptide sex pheromone, cAD1, secreted by potential recipient bacteria. The response is regulated by a cluster of genes that includes a positive regulatory determinant, traE1, able to activate key structural genes involved in the conjugative process. A negative regulatory determinant, traA, affects the expression of traE1 and is sensitive to the pheromone signal. Between the two determinants is a gene, iad, which encodes a small peptide, iAD1, a competitive inhibitor of cAD1. The determinants (traE1-iad-traA) are oriented such that iad and traE1 are transcribed in the same direction, opposite that of traA. Transcription of iad and traA starts between these determinants and moves outward in each case. A recent report from our laboratory, dealing with transcriptional fusions in the traE1-iad region (L. T. Pontius and D. B. Clewell, J. Bacteriol. 174:3152-3160, 1992), indicated that traE1 expression may be dependent on transcriptional read-through of a terminator(s) between iad and traE1. The present report provides direct analyses of relevant RNA species before and during induction and shows that indeed transcriptional read-through from iad is important in the initial expression of traE1. However, the data show that once traE1 is activated, it can then be expressed independently, probably because of TraE1 activating its own promoter. This view is also supported by genetic complementation studies. In addition, DNA binding studies with TraA showed that the protein binds to the promoter of iad. Binding of TraA to the region between iad and traE1 could not be detected; however, the involvement of TraA in influencing transcription termination in this region is still not ruled out, since additional factors could be involved. A model for the regulation of the pheromone response is presented.