Studies on the Processes of Construction of Active Structure of Bacterial Enterotoxin and of the Secretion to Milieu

细菌肠毒素活性结构构建及向环境分泌过程的研究

• 批准号: 11670280
• 负责人: OKAMOTO Keinosuke
• 金额: $ 2.3万
• 依托单位: OKAYAMA UNIVERSITY (2001)Tokushima Bunri University (1999-2000)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11670280/
• 关键词: Enterotoxin; Escherichia coli; Aeromonas; Secretion; Cytoplasmic Membrane; Maturation; Membrane Protein; 耐熱性下痢毒素; 膜タンパク質; ジスルフィド結合; 菌対外毒素; 毒素; 膜; 遺伝子

Several gram-negative bacteria cause severe diarrhea in human. Many of these enteric bacteria produce enterotoxins into outside of the cells, which are mainly responsible for the diarrhea induced by these bacteria. These enterotoxins are protein. In gram-negative bacteria, it is rare that the protein synthesized in cytoplasm emerges into the outside of cells. In order to emerge in the outside of the cell, the toxin must cross two membranes, inner membrane and outer membrane. And the toxins must be folded into the proper structure during the secretion. The process is called "maturation pathway of toxin". If the toxin failed to become mature toxin, the bacteria would lose the pathogenicity. Therefore, the maturation pathway of the toxin is closely related with the virulence of the bacteria.We examined the maturation pathway of two toxins. One is heat-stable enterotoxin of Escherichia coli (ST) and the other is enterotoxin of Aeromonas sobria. From the study on the former toxin, we found that ST was produced as precursor and processed in periplasm. Then, the intramolecular disulfide bonds are formed in the space by the action of DsbA and the STs cross the outer membrane though the tunnel of TolCs embedded in outer membrane.The study on the enterotoxin of Aeromonas sobria showed that the toxin form dimer in periplasm. The mutation analysis revealed that the carboxy terminal region of the toxin plays an important role in the dimerization. As the monomers of the enterotoxinis are easily digested in cells by proteases and never appear in culture medium, the carboxy terminal region of the hemolysin is important region for the secretion of hemolysin into culture medium.

几种革兰氏阴性菌引起人类严重腹泻。许多这些肠道细菌产生肠毒素进入细胞外，这是主要负责这些细菌引起的腹泻。这些肠毒素是蛋白质。在革兰氏阴性菌中，细胞质中合成的蛋白质很少出现在细胞外。为了在细胞外出现，毒素必须穿过两层膜，内膜和外膜。在分泌过程中，毒素必须折叠成适当的结构。这一过程被称为“毒素成熟途径”。如果毒素不能成为成熟毒素，细菌将失去致病性。因此，毒素的成熟途径与细菌的毒力密切相关。一种是大肠杆菌的耐热肠毒素（ST），另一种是温和气单胞菌的肠毒素。通过对前者毒素的研究发现，ST是作为前体产生并在周质中加工的。然后，在DsbA的作用下，在空间上形成分子内二硫键，ST通过包埋在外膜的TolCs通道穿过外膜。突变分析表明，毒素的羧基末端区域在二聚化中起重要作用。由于肠毒素的单体在细胞内容易被蛋白酶消化，而不会出现在培养基中，因此溶血素的羧基末端区域是溶血素分泌到培养基中的重要区域。

项目成果

櫻井 純: "細菌ハンドブック"株式会社サイエンスフォーラム(印刷中). (2002)

樱井淳：《细菌手册》科学论坛有限公司（正在出版）（2002）。

KEINOSUKE OKAMOTO: "Production of serine protease of Aeromonas sobria is controlled by the protein encoded by the gene lying adjacent to the 3' end of the protease gene"Microbiol.Immunol.. 44・9. 787-798 (2000)

KEINOSUKE OKAMOTO：“Aeromonas sobria 丝氨酸蛋白酶的产生是由位于蛋白酶基因 3 末端附近的基因编码的蛋白质控制的”Microbiol.Immunol.. 787-798 (2000)。

Keinosuke Okamoto, Tomohiko Nomura, Masaki Hamada, Takayuki Fukuda, Yoko Noguchi, and Yoshio Fuju: "Production of serine protease of Aeromonas sobria is controlled by the protein encoded by the gene lying adjacent to the 3' end of the protease gene."Micro

Keinosuke Okamoto、Tomohiko Nomura、Masaki Hamada、Takayuki Fukuda、Yoko Noguchi 和 Yoshio Fuju：“Aeromonas sobria 丝氨酸蛋白酶的产生是由位于蛋白酶基因 3 末端附近的基因编码的蛋白质控制的。”Micro

Keinosuke Okamoto, Hiroyasu Yamanaka, Miho Takeji, and Yoshio Fujii: "Region of heat-stable enterotoxin II of Escherichia coli involved in translocation across the outer membrane."Microbiol. Immunol.. 45 (5). 349-355 (2001)

Keinosuke Okamoto、Hiroyasu Yamanaka、Miho Takeji 和 Yoshio Fujii：“大肠杆菌热稳定肠毒素 II 区域参与跨外膜易位。”微生物学。

Hiroyasu Yamanaka, Hiroshi Izawa and Keinosuke Okamoto: "Carboxy Terminal Region Involved in the Activity of Escherichia coli TolC."J. Bacteriol.. 183 (23). 6961-6964 (2001)

Hiroyasu Yamanaka、Hiroshi Izawa 和 Keinosuke Okamoto：“羧基末端区域参与大肠杆菌 TolC 的活动。”J。