Autoprocessing of the Vibrio cholerae RTX toxin by the cysteine protease domain
Autoprocessing of the Vibrio cholerae RTX toxin by the cysteine protease domain
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DOI：
10.1038/sj.emboj.7601700
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发表时间：
2007-05-16
期刊：
影响因子：
11.4
通讯作者：
Satchell, Karla J. Fullner
中科院分区：
文献类型：
--
作者：
Sheahan, Kerri-Lynn;Cordero, Christina L.;Satchell, Karla J. Fullner
霍乱弧菌 RTX 是一种大型多功能细菌毒素，可引起肌动蛋白交联。由于其大小，预计它在易位到宿主细胞期间会经历蛋白水解切割，以将活性结构域传递到胞质溶胶。在这项研究中，我们鉴定了 RTX 毒素中的一个结构域，该结构域在大型梭菌糖基化毒素 TcdB、TcdA、TcnA 和 TcsL 中是保守的。来自创伤弧菌、耶尔森氏菌、光杆菌属和致病杆菌属的推定毒素；以及来自博德特氏菌属的丝状/血凝素样蛋白 FhaL。体内转染研究和纯化重组蛋白的体外表征表明，霍乱弧菌 RTX 毒素的这一结构域是一种自动加工半胱氨酸蛋白酶，其活性受到细胞内环境的刺激。 RTX 全毒素内的半胱氨酸点突变减弱了肌动蛋白交联活性，表明毒素的加工是毒素易位的重要步骤。总的来说，我们发现了一种新机制，通过这种机制，大细菌毒素和蛋白质通过易位后的自动加工向真核细胞胞质溶胶传递催化活性。
Vibrio cholerae RTX is a large multifunctional bacterial toxin that causes actin crosslinking. Due to its size, it was predicted to undergo proteolytic cleavage during translocation into host cells to deliver activity domains to the cytosol. In this study, we identified a domain within the RTX toxin that is conserved in large clostridial glucosylating toxins TcdB, TcdA, TcnA, and TcsL; putative toxins from V. vulnificus, Yersinia sp., Photorhabdus sp., and Xenorhabdus sp.; and a filamentous/ hemagglutinin-like protein FhaL from Bordetella sp. In vivo transfection studies and in vitro characterization of purified recombinant protein revealed that this domain from the V. cholerae RTX toxin is an autoprocessing cysteine protease whose activity is stimulated by the intracellular environment. A cysteine point mutation within the RTX holotoxin attenuated actin crosslinking activity suggesting that processing of the toxin is an important step in toxin translocation. Overall, we have uncovered a new mechanism by which large bacterial toxins and proteins deliver catalytic activities to the eukaryotic cell cytosol by autoprocessing after translocation.