THE GENETICS AND BIOCHEMISTRY OF PLASMID TRANSFER

毒力因子和抗生素耐药决定簇分布于 革兰氏阴性菌之间的接合质粒。 所有这些质粒 表达皮利，丝状结构，这是建立 DNA转移所必需的供体和受体细胞之间的接触。 在F接合系统中，有14个以上的基因在F接合系统中转移， 操纵子似乎参与F-菌毛的合成和表达。 其中许多产物尚未被鉴定，它们的分子作用 还没有被理解。 最近，我们已经表明，F-菌毛的合成， 亚基需要将F-traA产物加工成F-菌毛蛋白。 的 处理反应需要来自先前未识别的 转移操纵子基因（traQ），并可能需要额外的身份不明的 活动也是。 我们计划鉴定出基因和基因产物 参与F-菌毛蛋白亚基的合成，并研究其性质， 在这条途径中发生的生化反应。 我们还计划，与 转导质粒和嵌合质粒衍生物，以鉴定所有的 参与F-菌毛蛋白装配的基因和基因产物 亚单位，并研究它们之间的相互作用，并与 F-菌毛蛋白在组装过程中。 预计拟议的研究将 有助于我们理解菌毛的合成和表达， 阐明菌毛组装和回缩在接合中的作用。

Virulence factors and antibiotic resistance determinants are distributed among Gram-negative bacteria by conjugative plasmids. All such plasmids express pili, filamentous structures which are essential for establishing the contact between donor and recipient cells necessary for DNA transfer. In the F conjugative system, more than fourteen genes in the F transfer operon appear to be involved in the synthesis and expression of F-pili. Many of these products have not been identified, and their molecular role is not yet understood. Recently we have shown that synthesis of F-pilus subunits requires the processing of F-traA product to F-pilin. The processing reaction requires an activity from a previously unidentified transfer operon gene (traQ), and may require additional unidentified activities as well. We plan to identify the genes and gene products involved in F-pilin subunit synthesis, and investigate the nature of the biochemical reactions which occur in this pathway. We also plan, with transducing phages and chimeric plasmid derivitives, to identify all of the genes and gene products which are involved in the assembly of F-pilin subunits, and to investigate their interactions with each other and with F-pilin during the assembly process. The studies proposed are expected to contribute to our understanding of pilus synthesis and expression, and to elucidate the role of pilus assembly and retraction in conjugation.