A Novel Pheromone Quorum-Sensing System Controls the Development of Natural Competence in Streptococcus thermophilus and Streptococcus salivarius
A Novel Pheromone Quorum-Sensing System Controls the Development of Natural Competence in Streptococcus thermophilus and Streptococcus salivarius
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DOI：
10.1128/jb.01251-09
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发表时间：
2010-03-01
影响因子：
3.2
通讯作者：
Hols, Pascal
中科院分区：
文献类型：
--
作者：
Fontaine, Laetitia;Boutry, Celiine;Hols, Pascal
在链球菌物种中，能力发展的关键步骤是comX的转录诱导，它编码替代sigma因子sigma(X)，该因子正向调节DNA转化所需的基因。在属于mittis和mutans组的链球菌中，comX的诱导依赖于一个由分泌的信息素、组氨酸激酶和反应调节剂组成的三组分系统的激活。在嗜热链球菌中，寡肽转运体Ami在能力诱导条件下对comX的表达至关重要。这表明基于信号肽的产生和再输入的能力的不同调节途径。我们工作的目的是确定在嗜热链球菌LMD-9中参与comX诱导的早期步骤的主要参与者。利用转录组学方法，鉴定了四个高度诱导的早期能力操纵子。其中，我们发现了一个rgg样调节因子（Ster_0316）与一个编码24个氨基酸的疏水肽（Shp0316）的非注释基因相关。通过基因缺失，我们发现这两个基因对于comX的诱导是必不可少的。此外，在含有Shp0316 c端合成肽的培养基中，恢复了缺乏Shp0316菌株的comX诱导和转化。这些肽也诱导了嗜热链球菌和唾液链球菌菌株的能力，这些菌株不易转化或不能转化。总之，我们的研究结果表明，Ster_0316和Shp0316，更名为ComRS，是一个新的群体感应系统的两个成员，负责在唾液组物种中诱导comX，这与之前在链球菌中发现的经典磷中继三组分系统不同。
In streptococcal species, the key step of competence development is the transcriptional induction of comX, which encodes the alternative sigma factor sigma(X), which positively regulates genes necessary for DNA transformation. In Streptococcus species belonging to the mitis and mutans groups, induction of comX relies on the activation of a three-component system consisting of a secreted pheromone, a histidine kinase, and a response regulator. In Streptococcus thermophilus, a species belonging to the salivarius group, the oligopeptide transporter Ami is essential for comX expression under competence-inducing conditions. This suggests a different regulation pathway of competence based on the production and reimportation of a signal peptide. The objective of our work was to identify the main actors involved in the early steps of comX induction in S. thermophilus LMD-9. Using a transcriptomic approach, four highly induced early competence operons were identified. Among them, we found a Rgg-like regulator (Ster_0316) associated with a nonannotated gene encoding a 24-amino-acid hydrophobic peptide (Shp0316). Through genetic deletions, we showed that these two genes are essential for comX induction. Moreover, addition to the medium of synthetic peptides derived from the C-terminal part of Shp0316 restored comX induction and transformation of a Shp0316-deficient strain. These peptides also induced competence in S. thermophilus and Streptococcus salivarius strains that are poorly transformable or not transformable. Altogether, our results show that Ster_0316 and Shp0316, renamed ComRS, are the two members of a novel quorum-sensing system responsible for comX induction in species from the salivarius group, which differs from the classical phosphorelay three-component system identified previously in streptococci.