RUI: Role of VirC1 and VirC2 in Regulation of Substrate Delivery by the VirB/D4 Secretion Apparatus of Agrobacterium Tumefaciens

土壤细菌根癌农杆菌将蛋白质和DNA运输到宿主植物细胞中，导致感染部位的冠瘿瘤（“植物癌”）。由多种VirB蛋白和VirD 4组成的转运机制在细菌膜中作为复合物起作用，以促进DNA和蛋白质的输出，是其他医学上重要的细菌在其哺乳动物宿主中引起疾病所需的几种类似系统的原型。该项目的目标是表征两种蛋白质VirC 1和VirC 2，它们似乎可以提高通过这种运输装置递送DNA的效率。这项研究将测试VirC 1和VirC 2相互作用以将转移的DNA的来源拴系到细菌细胞膜上的特定位点，从而促进DNA与VirB/VirD 4分泌机制的相互作用的假设。将使用生化和显微镜方法来确定VirC 1是否与转运复合物的组分相关。将研究宿主细胞接触对这些相互作用的影响。生物化学和遗传学的方法将被用来探测VirC 1和VirC 2之间的相互作用。获得的数据还将揭示VirC 2位于细胞内的位置，以及VirC 1蛋白的特定区域是否对VirC 1的功能至关重要。结果将提供新的信息，两个不良特征的毒力蛋白，更广泛地说，通过一个重要的模型分泌系统的运输调节。根癌农杆菌被广泛用于将新基因导入植物，但由于一些植物（包括许多农业上重要的谷物）是不良宿主，因此其实用性受到限制。对VirC所起作用的这些调查很可能对迄今为止非宿主物种的遗传修饰产生重大影响，从而对全球粮食生产力产生重大影响。该项目将用于为本科生提供做研究的机会。

The soil bacterium Agrobacterium tumefaciens transports both proteins and DNA into a host plant cell, resulting in crown gall tumors ('plant cancer') at the infection site. The transport machinery, comprised of multiple VirB proteins and VirD4 working as a complex in the bacterial membrane to promote export of the DNA and proteins, is the prototype for several similar systems required for other medically significant bacteria to cause disease in their mammalian hosts. The goal of the project is to characterize two proteins, VirC1 and VirC2, that appear to enhance the efficiency of DNA delivery via this transport apparatus. This research will test the hypothesis that VirC1 and VirC2 interact to tether the source of the transferred DNA to specific sites on the bacterial cell membrane, thereby promoting DNA interactions with the VirB/VirD4 secretion machinery. Biochemical and microscopic approaches will be used to determine if VirC1 associates with components of the transport complex. The influence of host cell contact on these interactions will be investigated. Biochemical and genetic approaches will be used to probe for interactions between VirC1 and VirC2. The data obtained will also reveal where VirC2 is located within the cell, and whether a specific region of the VirC1 protein is essential for VirC1's functions. The results will provide novel information about two poorly characterized virulence proteins and, more broadly, the regulation of trafficking through an important model secretion system. Agrobacterium tumefaciens is widely used to introduce new genes into plants, but its utility is limited by the fact that some plants, including many agriculturally important grains, are poor hosts. These investigations into the roles played by VirC may well have significant implications for the genetic modification of hitherto non-host species, and hence for global food productivity. The project will be used to provide undergraduates in opportunities to do research.