Studies on the secretion and maturation pathway of bacterial exotoxin

细菌外毒素分泌及成熟途径的研究

基本信息

批准号：
14570237
负责人：
OKAMOTO Keinosuke
金额：
$ 2.24万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Diarrhea caused by the infection of bacteria is usually induced, by the action of the enterotoxin released from the bacteria into outside of the bacteria. It means that the diarrhea is not induced by the bacteria which can not secrete the active toxin into the outside of the cell, even if the bacteria synthesized the toxin in cell. In order to emerge outside of the cell as the active toxin, the toxin synthesized in cell must cross two membranes and form active structure during the secretion. Without this event, the bacteria can not express the toxic activity. We investigated the event in the productions of heat-stable enterotoxin (ST) of Escherichia coli, and enterotoxin of Aeromonas spp. It becomes clear that ST crosses the outer membrane though the pore formed by ToIC and that both Leu-412 and Leu-3 play an important role in the transportation of ST. This suggests that the compound attaching these two residues might interfere the secretion of ST, resulting the suppression of the toxicity of the bacteria producing ST. Subsequently, we found that the enterotoxin of Aeromas spp. possesses hemolytic activity, too. Then, we examined the hemolytic activity of the isolates from patients. Some of strains did not show hemolytic activity but showed enterotoxic activity. To clear the relationship between two activities, we cloned the gene encoding the new hemolysin. The results showed that there are differences in the DNA sequence between the wild type hemolysin gene and the new hemolysin gene in the amino terminal region. Furthermore, we found the protease is involved in the maturation of the hemolysin and that the protease function in cell to survive the bacteria in severe conditions, too.

细菌感染引起的腹泻通常是通过细菌释放的肠毒素进入细菌外部的作用而引起的。这意味着腹泻不是由细菌引起的，即使细菌在细胞内合成了毒素，也不能将活性毒素分泌到细胞外。为了作为活性毒素出现在细胞外，细胞内合成的毒素必须穿过两层膜并在分泌过程中形成活性结构。如果没有这个事件，细菌就无法表现出毒性活性。我们调查了大肠杆菌耐热肠毒素（ST）和气单胞菌肠毒素生产过程中的事件。很明显，ST 通过 ToIC 形成的孔穿过外膜，并且 Leu-412 和 Leu-3 在 ST 的运输中发挥着重要作用。这表明连接这两个残基的化合物可能会干扰ST的分泌，从而抑制产生ST的细菌的毒性。随后，我们发现气杆菌属的肠毒素。也具有溶血活性。然后，我们检查了患者分离株的溶血活性。一些菌株不表现出溶血活性，但表现出肠毒性活性。为了明确两种活性之间的关系，我们克隆了编码新溶血素的基因。结果表明，野生型溶血素基因与新型溶血素基因的DNA序列在氨基末端区域存在差异。此外，我们发现蛋白酶参与溶血素的成熟，并且蛋白酶在细胞中发挥作用以使细菌在恶劣条件下生存。

项目成果

期刊论文数量（62）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Sakae Arimoto-Kobayashi: "Inhibitory effects of (-)-epigallocatechin gallate on the mutation, DNA strand cleavage and DNA-adduct formation by heterocyclic amines"J.Arg.Food Chem.. 51・17. 5150-5153 (2003)

Sakae Arimoto-Kobayashi：“(-)-表没食子儿茶素没食子酸酯对杂环胺的突变、DNA链断裂和DNA加合物形成的抑制作用”J.Arg.Food Chem.. 51・17 (2003)。

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Hiroyasu Yamanaka, Tomohiko Nomura, Naoyuki Morisada, Sumio Shinoda, Keinosuke Okamoto: "Site-directed mutagenesis studies of the amino acid residue at position 412 of Escherichia coli TolC which is required for the activity"Microbial Pathogenesis. 33(2).

Hiroyasu Yamanaka、Tomohiko Nomura、Naoyuki Morisada、Sumio Shinoda、Keinosuke Okamoto：“大肠杆菌 TolC 412 位氨基酸残基的定点诱变研究，这是微生物发病机制活性所需的”。

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Ritsuko Yokoyama, Yoshio Fujii, Yoko Noguchi, Tomohiko, Nomura, Masahiko Akita, Kojun Setstu, Shigeo Yamamoto, Keinosuke Okamoto: "Physicochemical and Biological Properties of an Extracellular Serine Protease of Aeromonas sobria"Microbiology and Immunolog

Ritsuko Yokoyama、Yoshio Fujii、Yoko Noguchi、Tomohiko、Nomura、Masahiko Akita、Kojun Setstu、Shigeo Yamamoto、Keinosuke Okamoto：“气单胞菌胞外丝氨酸蛋白酶的物理化学和生物学特性”微生物学和免疫学