Small, noncoding RNAs and the evolution of Yersinia pestis virulence

描述(申请人提供)：细菌病原体的进化不仅通过蛋白质编码基因的获得或丢失发生，而且通过调节这些蛋白质编码基因的机制的改变而发生。这些改变可能导致基因相关的细菌，其表型截然不同。造成毁灭性疾病鼠疫的鼠疫耶尔森氏菌和引起轻度自限性疾病耶尔森氏病的假结核耶尔森氏菌就是这种现象的极好例子。虽然这两个物种在基因上高度相似，鼠疫杆菌被认为是假结核杆菌的最新克隆，但它们的传播途径、临床疾病表现和死亡率都有很大的不同。目前还不清楚这些密切相关的物种是如何导致这种不同的表型疾病的。近年来，小分子非编码RNA(SRNAs)在转录后水平对基因表达的调控受到了广泛关注。SRNAs与靶mRNAs碱基配对，改变翻译速率，从而影响蛋白质丰度。通过使用深度测序技术，我的实验室最近确定了鼠疫杆菌和假结核杆菌表达的sRNA(又名sRNA-ome)的全球谱系。这一分析表明，虽然大多数已鉴定的sRNA基因在两个物种中都是保守的，但鼠疫耶尔森氏菌基因组编码了5个假结核杆菌所没有的sRNA基因。由于我们已经证明，在肺鼠疫期间，至少需要这些鼠疫杆菌特异性sRNA中的一个才能完全毒力，我们推测，在鼠疫杆菌从假结核杆菌进化的过程中，鼠疫菌sRNA组的变化通过改变共同和/或不同毒力决定因素的调节，导致了其引起疾病鼠疫的特异性能力。我们将使用sRNA基因破坏结合动物感染模型来操纵鼠疫耶尔森氏菌的sRNA含量，以测试每个鼠疫特异性sRNA如何影响动物的腺鼠疫和肺鼠疫的严重程度和结果，如果是这样的话，这些sRNA促进毒力的机制。这些研究将为细菌病原体的进化提供独特的见解 转录后水平，并应广泛适用于其他密切相关但表型不同的物种。

DESCRIPTION (provided by applicant): The evolution of bacterial pathogens not only occurs through the gain or loss of protein-coding genes but also through changes in the mechanisms by which those protein-coding genes are regulated. These alterations may result in genetically related bacteria that are phenotypically quite distinct. Yersinia pestis, responsible for the devastating disease plague, and Yersinia pseudotuberculosis, the causative agent of the mild, self-limiting disease Yersiniosis, are excellent examples of this phenomenon. Although these two species are highly genetically similar and Y. pestis is considered to be a recently evolved clone of Y. pseudotuberculosis, the routes of transmission, clinical disease manifestations, and mortality rates caused by each are dramatically different. It is still unclear as to how these closely related species cause such phenotypically distinct diseases. In recent years, the regulation of gene expression at the post-transcriptional level by small, noncoding RNAs (sRNAs) has gained considerable attention. sRNAs base-pair with target mRNAs to alter translation rates and therefore affect protein abundance. By using deep sequencing technology, my laboratory recently determined the global repertoire of sRNAs (aka the sRNA-ome) expressed by both Y. pestis and Y. pseudotuberculosis. This analysis revealed that, while the majority of sRNA genes identified are conserved in both species, the Y. pestis genome encodes 5 sRNA genes that are absent from Y. pseudotuberculosis. As we have shown that at least one of these Y. pestis-specific sRNAs is required for full virulence during pneumonic plague, we hypothesize that changes in the sRNA-ome of Y. pestis during its evolution from Y. pseudotuberculosis contributed to its specific ability to cause the disease plague by changing the regulation of shared and/or distinct virulence determinants. We will use sRNA gene disruption combined with animal models of infection to manipulate the sRNA content of Y. pestis to test how each Y. pestis-specific sRNA may affect the severity and outcome of bubonic and pneumonic plague in animals and if so, the mechanisms by which these sRNAs contribute to virulence. These studies will provide a unique insight into the evolution of bacterial pathogens at the post-transcriptional level and should be broadly applicable to other closely related but phenotypically distinct species.