Conserved mutations in the pneumococcal bacteriocin transporter gene, blpA, result in a complex population consisting of producers and cheaters.
Conserved mutations in the pneumococcal bacteriocin transporter gene, blpA, result in a complex population consisting of producers and cheaters.
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肺炎球菌细菌素转运蛋白基因 blpA 的保守突变导致了一个由生产者和作弊者组成的复杂群体。
DOI：
10.1128/mbio.00179-11
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发表时间：
2011
期刊：
影响因子：
6.4
通讯作者：
Dawid,Suzanne
中科院分区：
文献类型：
--
作者：
Son,MatthewR;Shchepetov,Mikhail;Adrian,PeterV;Madhi,ShabirA;deGouveia,Linda;vonGottberg,Anne;Klugman,KeithP;Weiser,JeffreyN;Dawid,Suzanne
所有完全测序的肺炎链球菌都有一种blplocus，负责细菌素的产生和免疫。Bblocus的激活是由ABC转运蛋白BlpA分泌的多肽信息素BlpC的积累刺激的。Blplocus的特点是在blpC型和含有可能的细菌素和免疫基因的基因座上存在显著的多样性。此外，blpA基因可以代表单个大的开放阅读框架，也可以由于移码突变的存在而被分成几个较小的片段。在这项研究中，我们使用一组具有blp依赖的抑制和免疫的菌株来定义导致细菌素生产或免疫表型差异的基因变化。我们证明，在肺炎球菌菌株之间的竞争性相互作用中，blpA、blpC和细菌素/免疫含量的变化可能起着重要的作用。重要的是，在blpA中具有高度保守移码突变的菌株不能分泌细菌素或BlpC，但保留了对共生菌株产生的外源多肽信息素的反应能力，刺激了blp介导的免疫。这些“作弊者”菌株只能与细菌素产生菌共存，细菌素产生菌分泌同源BlpC并共享相同的免疫蛋白。这些相互作用的不同结果有助于解释细菌信息素、细菌素和免疫蛋白含量的异质性。肺炎链球菌生活在一个多菌环境中，通过细菌素这种小的抗菌肽来竞争有限的资源。肺炎链球菌基因组中一组保守的基因通过分泌一种信号信息素参与细菌素及其相关保护性免疫蛋白的产生。在这项研究中，我们表明，由于一种特定的转运蛋白的特定突变，相当数量的菌株已经失去了分泌细菌素和信号信息素的能力。由于保留了该基因的调节和免疫部分，这些“作弊者”菌株可以在细菌素产生菌的入侵下存活下来，而不需要花费细菌素分泌的成本。这种相互作用的结果取决于每个菌株的信息素、免疫蛋白和细菌素基因，因此菌种内的竞争导致细菌素、免疫蛋白和信息素含量的多样性。
All fully sequenced strains of Streptococcus pneumoniae possess a version of theblplocus, which is responsible for bacteriocin production and immunity. Activation of theblplocus is stimulated by accumulation of the peptide pheromone, BlpC, following its secretion by the ABC transporter, BlpA. Theblplocus is characterized by significant diversity inblpCtype and in the region of the locus containing putative bacteriocin and immunity genes. In addition, theblpAgene can represent a single large open reading frame or be divided into several smaller fragments due to the presence of frameshift mutations. In this study, we use a collection of strains withblp-dependent inhibition and immunity to define the genetic changes that bring about phenotypic differences in bacteriocin production or immunity. We demonstrate that alterations inblpA,blpC, and bacteriocin/immunity content likely play an important role in competitive interactions between pneumococcal strains. Importantly, strains with a highly conserved frameshift mutation inblpAare unable to secrete bacteriocins or BlpC, but retain the ability to respond to exogenous peptide pheromone produced by cocolonizing strains, stimulatingblp-mediated immunity. These “cheater” strains can only coexist with bacteriocin-producing strains that secrete their cognate BlpC and share the same immunity proteins. The variable outcome of these interactions helps to explain the heterogeneity of theblppheromone, bacteriocin, and immunity protein content.IMPORTANCEStreptococcus pneumoniae resides in a polymicrobial environment and competes for limited resources by the elaboration of small antimicrobial peptides called bacteriocins. A conserved cluster of genes in the S. pneumoniae genome is involved in the production of bacteriocins and their associated protective immunity proteins through secretion of a signaling pheromone. In this study, we show that a significant number of strains have lost the ability to secrete bacteriocins and signaling pheromones due to a specific mutation in a dedicated transporter protein. Because the regulatory and immunity portion of the locus is retained, these “cheater” strains can survive in the face of invasion from a bacteriocin-producing strain without the cost of bacteriocin secretion. The outcome of such interactions depends on each strain’s repertoire of pheromone, immunity protein, and bacteriocin genes, such that intrastrain competition drives the diversity in bacteriocin, immunity protein, and pheromone content.