Diversifying selection at the Bacillus quorum-sensing locus and determinants of modification specificity during synthesis of the ComX pheromone
Diversifying selection at the Bacillus quorum-sensing locus and determinants of modification specificity during synthesis of the ComX pheromone
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DOI：
10.1128/jb.186.1.15-21.2004
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发表时间：
2004-01-01
影响因子：
3.2
通讯作者：
Dubnau, D
中科院分区：
文献类型：
--
作者：
Ansaldi, M;Dubnau, D
枯草芽孢杆菌的感受态群体传感系统由双组分调节蛋白ComP（组胺酸激酶）和反应调节剂ComA（细胞外信息素（ComX））以及蛋白质水解切割和修饰所需的蛋白质组成。前ComX（ComQ）。ComQ和pre-ComX对于活性信息素的产生都是必要的和足够的，所述活性信息素作为异戊二烯化肽释放。实验室菌株168和一些自然分离的杆菌在它们的信息素的一级序列以及它们的异戊二烯基加合物的质量方面不同。我们已经表明，ComX，ComQ和ComP的膜定位传感器结构域在与B实验室菌株密切相关的杆菌的天然分离物中具有高度多态性。枯草杆菌。在这项研究中，我们使用了两个统计检验（同义和非同义替换率的比率和田岛D测试）来证明这些多态性序列是通过多样化选择而不是中性漂移进化的。我们表明，异戊二烯基衍生物的选择是由C-末端（成熟）序列的前ComX，而不是由ComQ蛋白。这些研究结果的进化的群体感应系统和蛋白质-蛋白质相互作用参与确定特异性的影响进行了讨论。
The competence quorum-sensing system of Bacillus subtilis consists of two-component regulatory proteins, ComP (histidine kinase) and the response regulator, ComA, an extracellular pheromone (ComX), and a protein that is needed for the proteolytic cleavage and modification of pre-ComX (ComQ). ComQ and pre-ComX are both necessary and sufficient for the production of active pheromone, which is released as an isoprenylated peptide. Laboratory strain 168 and a number of natural isolates of bacilli differ in the primary sequences of their pheromones as well as in the masses of their isoprenyl adducts. We have shown that ComX, ComQ, and the membrane-localized sensor domain of ComP are highly polymorphic in natural isolates of bacilli all closely related to the laboratory strain of B. subtilis. In this study, we used two statistical tests (the ratio of synonymous and nonsynonymous substitution rates and the Tajima D test) to demonstrate that these polymorphic sequences evolved by diversifying selection rather than by neutral drift. We show that the choice of isoprenyl derivative is determined by the C-terminal (mature) sequence of pre-ComX rather than by the ComQ protein. The implications of these findings for the evolution of the quorum-sensing system and for the protein-protein interactions involved in determining specificity are discussed.