MECHANISM OF ACTION OF E. COLI PROTEIN EXPORT FACTORS

本研究对E.杆菌 SecB蛋白识别注定要输出的蛋白质， 细胞质 遗传学研究将确定哪些特征， 输出蛋白被SecB蛋白识别，SecB蛋白的哪一部分 蛋白质参与识别。 此外，生物化学研究 将确定secB突变对蛋白质易位的影响， 体外并表征SecB之间可能存在的任何相互作用 蛋白质和翻译输出蛋白质的多核糖体。 为未来 研究，这些实验将扩展到详细的分析， SecB蛋白与其底物之间的相互作用。 第二个目标是通过突变体分离鉴定其他蛋白质， 输出因子的功能类似于SecB蛋白，但特异于 不同的输出蛋白质谱。 因为secB基因突变会影响 如果仅输出输出蛋白质的子集，则存在至少一个 蛋白质输出的SecB非依赖性途径。 该途径可能包括 该因子在功能上类似于SecB蛋白。 如果这个模型是 正确的，使用多种途径可以为细胞提供一种手段， 用它来调节不同蛋白质输出的位点和速率。 为了使细胞有序生长，亚细胞结构的组装必须 仔细控制;这项研究的长期目标是了解 使细胞能够执行这一基本功能的机制。

The research involves analysis of the mechanism of action of the E. coli SecB protein in recognition of proteins destined to be exported out of the cell cytoplasm. Genetic studies will determine what features of the exported protein are recognized by SecB protein and what part of SecB protein is involved in the recognition. In addition, biochemical studies will determine the effects of secB mutations on protein translocation in vitro and characterize any interactions that might exist between SecB protein and polysomes that are translating exported proteins. For future research, these experiments will be extended to a detailed analysis of the interaction between SecB protein and its substrate. A second goal is to identify, through mutant isolation, other protein export factors that function like SecB protein but are specific for a different spectrum of exported proteins. Bacause secB mutations afect the export of only a subset of exported proteins, there is at lease one SecB-independent pathway for protein export. This pathway may include a factor that is functionally analogous to SecB protein. If this model is correct, the use of multiple pathways could provide the cell with a means with which to regulate the sites and rates of exort of different proteins. For orderly cell growth, the assembly of subcellular structures must be carefully controlled; the long term goal of this research is to understand the mechanism that allows the cell to perform this basic function.