Characteristics of ion tranport systems in Vibrio parahaemolyticus and Staphylococcus aureus

副溶血性弧菌和金黄色葡萄球菌是日本食物中毒的两个主要原因。金黄色葡萄球菌也是医院感染的主要原因。前者生长需要Na^+，后者是Na^+相关微生物。基于这些特点，我们研究了这些微生物的离子传输系统，特别是Na^+传输系统。我们从生物化学和分子生物学方面对这些转运系统进行了表征，并研究了这些细菌的嗜盐性或耐盐性与Na^+转运之间的关系。我们鉴定了副溶血性弧菌Na^+/H^+的反向转运蛋白，并克隆了该反向转运蛋白的基因。随后，我们对该基因进行了测序，并揭示了该反转运蛋白的主要结构。我们发现大肠杆菌Na^+/H^+反转运蛋白与NhaB Na^+/H^+反转运蛋白序列相似。因此，我们确定副溶血性嗜血杆菌的反向转运蛋白为NhaB。我们鉴定了Na^+/H^+反转运蛋白的几个功能性氨基酸残基。我们还发现了第三个Na^+/H^+反转运子NhaD，并对其进行了表征。该基因被克隆并测序。我们发现它是一种新型的Na^+/H^+反转运子。结果表明，Na^+/H^+反转运体对嗜盐性和耐盐性非常重要。Na^+/葡萄糖同调体（SglS）也进行了表征。我们克隆了结构基因并对其进行了测序。我们发现SglS与人类SGLT，Na^+/葡萄糖同调体序列相似。研究了金黄色葡萄球菌外翻膜泡的制备方法。我们发现在这种微生物中存在Na^+/H^+反转运蛋白。我们对它进行了表征，克隆了结构基因，并对它们进行了测序。Na^+/H^+反转运子是一种新型的反转运子。我们发现这种反向转运蛋白参与耐盐性和细胞内pH调节。

Vabrio parahaemolyticus and Staphylococcus aureus are two major causes of food poisoning in Japan. S.aureus is also a major cause of infection in hospitals. The former requires Na^+ for its growth, and the latter is a Na^+-torelant microorganism. Base on these characteristics, we investigated ion transport systems, especially Na^+ transport systems, in these microorganisms. We biochemically and molecular biologically characterized such transport systems, and investigated relationship between halophilicity or halotorelance of these bacteria and Na^+ transport.We characterized the Na^+/H^+ antiporter in V.parahaemolyticus and cloned gene for the antiporter. We thereafter sequenced the gene and revealed the primary structure of the antiporter. We found sequence similarity between the Na^+/H^+ antiporter and the NhaB Na^+/H^+ antiporter of Escherichia coli. Thus, we designated the antiporter of V.parahaemolyticus as NhaB.We identified several functional amino acid residues of the Na^+/H^+ antiporters. We also found the third Na^+/H^+ antiporter NhaD and characterized it. The gene was cloned and sequenced. We found that it was a new type of Na^+/H^+ antiporter. It became claer that the Na^+/H^+ antiporters are very important for halophilicity and halotorelance. The Na^+/glucose symporter (SglS) was also characterized. We cloned the structural gene and sequenced it. We found sequence similarity between the SglS and human SGLT,Na^+/glucose symporter.We developed a method for the preparation of everted membrane vesicles of S.aureus. We found that Na^+/H^+ antiporter is present in this microorganism. We characterized it, cloned the structural genes and sequenced them. This Na^+/H^+ antiporter was revelaed to be a novel type of antiporter. We found that this antiporter is involved in halotorelance and intracellular pH regulation.