文章基本信息

标题：Phospholipase A activity of adenylate cyclase toxin mediates translocation of its adenylate cyclase domain
本地全文：下载
作者：David González-Bullón ; Kepa B. Uribe ; César Martín 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：33
页码：E6784-E6793
DOI：10.1073/pnas.1701783114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Adenylate cyclase toxin (ACT or CyaA) plays a crucial role in respiratory tract colonization and virulence of the whooping cough causative bacterium Bordetella pertussis . Secreted as soluble protein, it targets myeloid cells expressing the CD11b/CD18 integrin and on delivery of its N-terminal adenylate cyclase catalytic domain (AC domain) into the cytosol, generates uncontrolled toxic levels of cAMP that ablates bactericidal capacities of phagocytes. Our study deciphers the fundamentals of the heretofore poorly understood molecular mechanism by which the ACT enzyme domain directly crosses the host cell membrane. By combining molecular biology, biochemistry, and biophysics techniques, we discover that ACT has intrinsic phospholipase A (PLA) activity, and that such activity determines AC translocation. Moreover, we show that elimination of the ACT–PLA activity abrogates ACT toxicity in macrophages, particularly at toxin concentrations close to biological reality of bacterial infection. Our data support a molecular mechanism in which in situ generation of nonlamellar lysophospholipids by ACT–PLA activity into the cell membrane would form, likely in combination with membrane-interacting ACT segments, a proteolipidic toroidal pore through which AC domain transfer could directly take place. Regulation of ACT–PLA activity thus emerges as novel target for therapeutic control of the disease.
关键词：bacterial toxins ; RTX toxin family ; protein translocation ; biological membranes ; membrane remodeling