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首页> 美国卫生研究院文献>Journal of Bacteriology >Pheromone-Regulated Expression of Sex Pheromone Plasmid pAD1-Encoded Aggregation Substance Depends on at Least Six Upstream Genes and a cis-Acting Orientation-Dependent Factor
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Pheromone-Regulated Expression of Sex Pheromone Plasmid pAD1-Encoded Aggregation Substance Depends on at Least Six Upstream Genes and a cis-Acting Orientation-Dependent Factor

机译：信息素调控性信息素质粒pAD1编码的聚集物质的表达取决于至少六个上游基因和一个顺式作用方向依赖性因子

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摘要

Conjugative transfer of Enterococcus faecalis-specific sex pheromone plasmids relies on an adhesin, called aggregation substance, to confer a tight cell-to-cell contact between the mating partners. To analyze the dependence of pAD1-encoded aggregation substance, Asa1, on pheromone induction, a variety of upstream fragments were fused to an α-amylase reporter gene, amyL, by use of a novel promoter probe vector, pAMY-em1. For pheromone-regulated α-amylase activity, a total of at least six genes, traB, traC, traA, traE1, orfY, and orf1, are required: TraB efficiently represses asa1 (by a mechanism unrelated to its presumptive function in pheromone shutdown, since a complete shutdown is observed exclusively in the presence of traC); only traC can relieve traB-mediated repression in a pheromone-dependent manner. In addition to traB, traA is required but not sufficient for negative control. Mutational inactivation of traE1, orfY, or orf1, respectively, results in a total loss of α-amylase activity for constructs normally mediating constitutive expression. Inversion of a fragment covering traA, P0, and traE1 without disrupting any gene or control element switches off amyL or asa1 expression, indicating the involvement of a cis-acting, orientation-dependent factor (as had been shown for plasmid pCF10). Unexpectedly, pAD1 represses all pAMY-em1 derivatives in trans, while its own pheromone-dependent functions are unaffected. The discrepancy between the new data and those of former studies defining TraE1 as a trans-acting positive regulator is discussed.
机译：粪肠球菌特异性性信息素质粒的结合转移依赖于一种称为聚集物质的粘附素，以赋予交配伴侣之间紧密的细胞间接触。为了分析pAD1编码的聚集物质Asa1对信息素的依赖性，通过使用新型启动子探针载体pAMY-em1，将多种上游片段与α-淀粉酶报道基因amyL融合。对于信息素调节的α-淀粉酶活性，总共需要至少六个基因traB，traC，traA，traE1，orfY和orf1：TraB有效抑制asa1（通过与其在信息素关闭中的推测功能无关的机制，因为仅在traC存在下才能观察到完全关闭）；只有traC可以以信息素依赖的方式缓解traB介导的抑制。除traB外，还需要traA，但不足以用于阴性对照。 traE1，orfY或 orf1 的突变失活分别导致通常介导组成型表达的构建体的α-淀粉酶活性完全丧失。覆盖 traA ，P0和 traE1 的片段的倒置而不破坏任何基因或控制元件，会关闭 amyL 或 asa1 表达，表明参与了顺式作用，方向依赖性因子（如质粒pCF10所示）。出乎意料的是，pAD1抑制了 trans 中的所有pAMY-em1衍生物，而其自身依赖信息素的功能却不受影响。讨论了新数据与以前将TraE1定义为 trans 作用正调控子的研究之间的差异。

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