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首页> 外文期刊>Journal of bacteriology >Regulation of Bacteriocin Production in Streptococcus mutans by the Quorum-Sensing System Required for Development of Genetic Competence
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Regulation of Bacteriocin Production in Streptococcus mutans by the Quorum-Sensing System Required for Development of Genetic Competence

机译：遗传能力发展所需的群体感应系统调控变形链球菌中细菌素的产生

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In Streptococcus mutans, competence for genetic transformation and biofilm formation are dependent on the two-component signal transduction system ComDE together with the inducer peptide pheromone competence-stimulating peptide (CSP) (encoded by comC). Here, it is shown that the same system is also required for expression of the nlmAB genes, which encode a two-peptide nonlantibiotic bacteriocin. Expression from a transcriptional nlmAB′-lacZ fusion was highest at high cell density and was increased up to 60-fold following addition of CSP, but it was abolished when the comDE genes were interrupted. Two more genes, encoding another putative bacteriocin and a putative bacteriocin immunity protein, were also regulated by this system. The regions upstream of these genes and of two further putative bacteriocin-encoding genes and a gene encoding a putative bacteriocin immunity protein contained a conserved 9-bp repeat element just upstream of the transcription start, which suggests that expression of these genes is also dependent on the ComCDE regulatory system. Mutations in the repeat element of the nlmAB promoter region led to a decrease in CSP-dependent expression of nlmAB′-lacZ. In agreement with these results, a comDE mutant and mutants unable to synthesize or export CSP did not produce bacteriocins. It is speculated that, at high cell density, bacteriocin production is induced to liberate DNA from competing streptococci.
机译：在变形链球菌中，遗传转化和生物膜形成的能力取决于两组分信号转导系统ComDE以及诱导剂肽信息素能力刺激肽（CSP）（由 comC编码） / em>）。在这里，显示了 nlmAB 基因的表达也需要相同的系统，该基因编码两肽非抗生素细菌素。转录 nlmAB '- lacZ 融合蛋白的表达在高细胞密度下最高，并在加入CSP后增加至60倍，但当 > comDE 基因被打断。该系统还调节了另外两个编码另一个推定的细菌素和推定的细菌素免疫蛋白的基因。这些基因和另外两个推定的细菌素编码基因以及编码推定的细菌素免疫蛋白的基因的上游区域在转录起始上游包含一个保守的9 bp重复元件，这表明这些基因的表达还取决于ComCDE监管系统。 nlmAB 启动子区域的重复元件突变导致 nlmAB ' -lacZ 的CSP依赖性表达降低。与这些结果一致， comDE 突变体和无法合成或输出CSP的突变体均不产生细菌素。据推测，在高细胞密度下，诱导细菌素产生以从竞争性链球菌中释放DNA。

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