Genetic and Physiological Analysis of Tn21-Encoded Mercury Transport

这项研究的目的是利用遗传和 生理分析，以研究周质的作用 和由Tn21的mer操纵子编码的膜蛋白， 汞运输。 我们之前已经通过分析表明， 缺失和移码突变， 周质蛋白和merT编码的膜蛋白是 既需要耐汞性，也需要汞诱导性 汞吸收。 我们将使用两种药物， 定点诱变和体外定位羟胺 诱变以鉴定特定的氨基酸残基， 参与汞结合和抗汞性。 分子 膜蛋白的拓扑结构将通过以下方式进行研究： 与碱性磷酸酶融合，只有当 分泌到周质中 基本生理 汞迁移系统的特征将包括 研究：对渗透压休克的敏感性，对 各种宿主功能、巯基试剂要求，以及 对能量代谢抑制剂和干扰剂的敏感性。

The objectives of this study are to use genetic and physiological analyses to investigate the roles of periplasmic and membrane proteins encoded by the mer operon of Tn21 in mercury transport. We have previously shown by analysis of deletion and frameshift mutations that the merP-encoded periplasmic protein and the merT-encoded membrane protein are required both for mercury resistance and for mercury-inducible mercury uptake. We will use both oligonucleotide-directed, site-specific mutagenesis and localized in vitro hydroxylamine mutagenesis to identify specific amino acid residues that are involved in mercury binding and mercury resistance. Molecular topology of membrane proteins will be investigated by making fusions with alkaline phosphatase, which is active only if secreted into the periplasm. Basic physiological characterization of the mercury transport system will include investigation of: sensitivity to osmotic shock, dependence on various host function, requirement for sulfhydryl reagents, and sensitivity to inhibitors and uncoulers of energy metabolism.