Mazar Joseph, Cotter Peggy A
Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106-9610, USA.
Mol Microbiol. 2006 Nov;62(3):641-54. doi: 10.1111/j.1365-2958.2006.05392.x. Epub 2006 Sep 25.
Two-partner secretion (TPS) is the most widely distributed secretion pathway known. These systems export large exoproteins through highly conserved channel-forming beta-barrel proteins. Filamentous haemagglutinin (FHA), expressed by Bordetella species, is the prototypical TPS family member. Here we show that the C-terminus of mature FHA, as opposed to the N-terminus as previously proposed, is exposed on the cell surface and is required for mediating adherence to cultured epithelial cells. We show that the C-terminus of the FHA pro-protein (FhaB) is required for FHA function in vitro and in vivo and we show that cleavage of FhaB to form FHA is not the mechanism by which FHA is released from the cell. Based on these data, we propose a new model for TPS. This model provides an explanation for the energetics of export of globular protein domains across membranes in the absence of ATP and it suggests a new mechanism for the control of protein folding.
双组分分泌（TPS）是已知分布最广泛的分泌途径。这些系统通过高度保守的形成通道的β-桶状蛋白输出大型胞外蛋白。由博德特氏菌属表达的丝状血凝素（FHA）是TPS家族的典型成员。在这里，我们表明，与先前提出的N端相反，成熟FHA的C端暴露在细胞表面，并且是介导与培养的上皮细胞粘附所必需的。我们表明，FHA前体蛋白（FhaB）的C端在体外和体内对FHA功能都是必需的，并且我们表明FhaB切割形成FHA不是FHA从细胞释放的机制。基于这些数据，我们提出了一种新的TPS模型。该模型解释了在没有ATP的情况下球状蛋白结构域跨膜输出的能量学，并提出了一种控制蛋白质折叠的新机制。
