Modulation of Vibrio mimicus hemolysin through limited proteolysis by an endogenous metalloprotease
Modulation of Vibrio mimicus hemolysin through limited proteolysis by an endogenous metalloprotease
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DOI：
10.1111/j.1742-4658.2008.06827.x
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发表时间：
2009-02-01
期刊：
影响因子：
5.4
通讯作者：
Miyoshi, Shin-ichi
中科院分区：
文献类型：
--
作者：
Mizuno, Tamaki;Sultan, Syed Z.;Miyoshi, Shin-ichi
拟态弧菌是人类胃肠炎和食物中毒的病原体，该物种产生肠毒性溶血素（拟态弧菌溶血素）作为毒力决定因子。拟态弧菌溶血素作为80 kDa前体分泌，其随后通过Arg 151-Ser 152键的裂解去除N-末端前肽而转化为66 kDa成熟毒素。在这篇文章中，我们研究了内源性金属蛋白酶（拟态弧菌蛋白酶）在拟态弧菌溶血素成熟过程中的作用。使用纯化的蛋白质的体外实验表明，尽管它在早期阶段通过切割Asn 157-Val 158键激活前体，但拟态弧菌蛋白酶最终通过去除C-末端多肽将激活的和生理上成熟的毒素转化为51 kDa的蛋白质。这种51 kDa的衍生物不能溶解红细胞，因为它不能与红细胞膜结合。发现拟态弧菌蛋白酶阴性菌株在细菌生长的对数期产生高水平的拟态弧菌溶血素，并且即使在稳定期也保持高的溶血活性。这些发现表明，尽管拟态弧菌蛋白酶在体内与毒素成熟没有直接关系，但它可以通过有限的蛋白水解来调节拟态弧菌溶血素和/或其前体的活性。
Vibrio mimicus is a causative agent of human gastroenteritis and food poisoning, and this species produces an enterotoxic hemolysin (V. mimicus hemolysin) as a virulence determinant. Vibrio mimicus hemolysin is secreted as an 80 kDa precursor, which is later converted to the 66 kDa mature toxin through removal of an N-terminal propeptide via cleavage of the Arg151-Ser152 bond. In this article, we investigate the role of the endogenous metalloprotease (V. mimicus protease) in the maturation of V. mimicus hemolysin. In vitro experiments using purified proteins showed that, although it activated the precursor at the early stage via cleavage of the Asn157-Val158 bond, V. mimicus protease finally converted the activated and physiologically maturated toxin to a 51 kDa protein through removal of the C-terminal polypeptide. This 51 kDa derivative was unable to lyse erythrocytes because of its inability to bind to the erythrocyte membrane. Vibrio mimicus protease-negative strains were found to produce high levels of V. mimicus hemolysin at the logarithmic phase of bacterial growth and maintained high hemolytic activity even at the stationary phase. These findings indicate that, although it is not directly related to toxin maturation in vivo, V. mimicus protease can modulate the activity of V. mimicus hemolysin and/or its precursor through limited proteolysis.