Vectorial transport and folding of an autotransporter virulence protein during outer membrane secretion
Vectorial transport and folding of an autotransporter virulence protein during outer membrane secretion
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DOI：
10.1111/j.1365-2958.2009.06607.x
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发表时间：
2009-03-01
影响因子：
3.6
通讯作者：
Clark, Patricia L.
中科院分区：
文献类型：
--
作者：
Junker, Mirco;Besingi, Richard N.;Clark, Patricia L.
自转运蛋白（autotransporter，AT）是革兰氏阴性菌胞外毒力蛋白的一个大家族，其特征是在成熟毒力蛋白中含有一个β-螺旋结构域。目前尚不清楚这些蛋白质如何快速有效地穿过外膜（OM），而无需外部能量源（如ATP或质子梯度）的帮助。文献中的验证结果导致了几种提出的AT OM分泌机制，包括协调过程或具有不同方向性的载体分泌。我们将成对的半胱氨酸残基引入到乘客序列的perceptin，AT的毒力蛋白从百日咳博德特氏菌，并显示OM分泌的乘客域的摊位，由于形成的二硫键。我们进一步表明，C-末端的percurin乘客域β-螺旋交叉OM第一，其次是N-末端部分的毒力蛋白。体内蛋白水解消化表明，C-末端在失速期间暴露于细胞外环境，并形成稳定的结构。这些AT分泌和折叠特征可以潜在地促进有效分泌。
Autotransporter (AT) proteins are a large and diverse family of extracellular virulence proteins from Gram-negative bacteria, characterized by a central beta-helix domain within the mature virulence protein. It is not clear how these proteins cross the outer membrane (OM) quickly and efficiently, without assistance from an external energy source such as ATP or a proton gradient. Conflicting results in the literature have led to several proposed mechanisms for AT OM secretion, including a concerted process, or vectorial secretion with different directionalities. We introduced pairs of cysteine residues into the passenger sequence of pertactin, an AT virulence protein from Bordetella pertussis, and show that OM secretion of the passenger domain stalls due to the formation of a disulphide bond. We further show that the C-terminus of the pertactin passenger domain beta-helix crosses the OM first, followed by the N-terminal portions of the virulence protein. In vivo proteolytic digestion shows that the C-terminus is exposed to the extracellular milieu during stalling, and forms stable structure. These AT secretion and folding features can potentially facilitate efficient secretion.