Heveker N, Bonnaffé D, Ullmann A
Unité de Biochimie des Régulations Cellulaires, Institut Pasteur, Paris, France.
J Biol Chem. 1994 Dec 30;269(52):32844-7.
Adenylate cyclase toxin (ACT), a virulence factor of Bordetella pertussis, acquires hemolytic and toxic activities after post-translational modification of the cyaA gene product, CyaA. The exact nature of this modification is unknown, but homology to the related repeat toxin alpha-hemolysin of Escherichia coli suggests that fatty acylation of a lysine residue may be involved. In the present study, we used an in vitro chemical approach to acylate unmodified, inactive adenylate cyclase protoxin by using a new water-soluble compound, acylpyrophosphate. We show that undirected transfer of lauric, myristic, or palmitic acid chains to the CyaA protoxin is able to confer both hemolytic and toxic activities to ACT. The chemically modified protoxin shows a specific requirement for Ca2+ ions for toxic activity, as does the wild type toxin. However, the toxic and hemolytic activities of chemically modified ACT are low in comparison to ACT modified in vivo, suggesting that in vitro fatty acylation of the protoxin involves random modification of nucleophilic residues present in the toxin in contrast to the in vivo modification of specific sites.
腺苷酸环化酶毒素（ACT）是百日咳博德特氏菌的一种毒力因子，在cyaA基因产物CyaA进行翻译后修饰后获得溶血和毒性活性。这种修饰的确切性质尚不清楚，但与大肠杆菌相关的重复毒素α-溶血素的同源性表明，赖氨酸残基的脂肪酰化可能参与其中。在本研究中，我们使用一种新的水溶性化合物酰基焦磷酸，采用体外化学方法对未修饰的无活性腺苷酸环化酶原毒素进行酰化。我们表明，月桂酸、肉豆蔻酸或棕榈酸链向CyaA原毒素的无定向转移能够赋予ACT溶血和毒性活性。化学修饰的原毒素对Ca2+离子的毒性活性有特定需求，野生型毒素也是如此。然而，与体内修饰的ACT相比，化学修饰的ACT的毒性和溶血活性较低，这表明原毒素的体外脂肪酰化涉及对毒素中存在的亲核残基的随机修饰，这与体内特定位点的修饰形成对比。
