Regulation of the Sinorhizobium meliloti ExoS/ChvI signaling pathway critical for host infection

项目摘要/摘要 许多α-蛋白细菌侵入真核宿主的细胞，造成致病或有益的后果。示例 在这种α-蛋白细菌中有人类病原体布鲁氏菌和巴尔通氏菌以及植物共生菌 中华根瘤菌。值得注意的是，尽管这些阿尔法蛋白细菌针对不同宿主中不同类型的细胞， 它们都需要一个保守的细菌双组分信号通路才能成功地与宿主相互作用： 布鲁氏菌中的BvrS/BvrR、巴尔通菌中的Bats/Batr、中华根瘤菌中的ExOS/ChvI。突变细菌缺乏 该途径不能侵入宿主细胞，并表现出多效性表型，如改变细胞被膜功能。 然而，这些缺陷背后的分子机制还不是很清楚。向澄清 这个保守的信号通路的关键作用，本项目重点研究EXOS/ChvI信号通路 研究与真核宿主相互作用的模式α-蛋白细菌--苜蓿中华根瘤菌。最近 全基因组研究发现，在苜蓿链霉菌的exos/chvI调控子中存在蛋白编码基因。这项建议 在这项研究的基础上建立起来，并使用分子遗传学方法来阐明这种保守的 调控途径。该项目的具体目标是：(1)识别直接受 EXOS/ChvI，(2)识别EXOS/ChvI的调控输入，以及(3)鉴定转录靶基因 EXOS/CHVI。这项研究将为深入了解这一重要的信号通路所控制的功能提供帮助 在主持人互动期间。此外，该项目将提供有价值的生物医学研究培训，以 本科生和硕士研究生，包括那些在生物医学研究中代表性不足的群体 事业。

PROJECT SUMMARY/ABSTRACT Many alpha-proteobacteria invade cells of eukaryotic hosts with pathogenic or beneficial outcomes. Examples of such alpha-proteobacteria are the human pathogens Brucella and Bartonella and the plant symbiont Sinorhizobium. Remarkably, although these alpha-proteobacteria target different cell types in different hosts, they all require a conserved bacterial two-component signaling pathway for successful host interaction: BvrS/BvrR in Brucella, BatS/BatR in Bartonella, and ExoS/ChvI in Sinorhizobium. Mutant bacteria deficient in this pathway fail to invade host cells and exhibit pleiotropic phenotypes such as altered cell envelope function. However, the molecular mechanisms underlying these defects are not well understood. Toward elucidating the crucial roles of this conserved signaling pathway, this project focuses on the ExoS/ChvI signaling pathway of Sinorhizobium meliloti, a model alpha-proteobacterium for studying interactions with eukaryotic hosts. A recent genome-wide study identified 64 protein-encoding genes in the ExoS/ChvI regulon of S. meliloti. This proposal builds from that study and uses molecular genetic approaches to clarify the critical functions of this conserved regulatory pathway. Specific aims of the project are to: (1) Identify small RNA genes directly regulated by ExoS/ChvI, (2) Identify regulatory inputs to ExoS/ChvI, and (3) Characterize transcriptional target genes of ExoS/ChvI. This study will provide insight into the functions controlled by this important signaling pathway during host interaction. In addition, the project will provide valuable biomedical research training to undergraduate and master’s students, including those from groups underrepresented in biomedical research careers.