Conformational dynamics of protein transporter FhaC: large-scale motions of plug helix
Conformational dynamics of protein transporter FhaC: large-scale motions of plug helix
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DOI：
10.1111/mmi.12585
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发表时间：
2014-06-01
影响因子：
3.6
通讯作者：
Jacob-Dubuisson, Francoise
中科院分区：
文献类型：
--
作者：
Guerin, Jeremy;Baud, Catherine;Jacob-Dubuisson, Francoise
FhaC是百日咳剂百日咳博德泰拉的一种完整的外膜蛋白，它介导一种主要毒力因子，丝状血凝素粘连素FHA向细胞表面的运输。FHA/FhaC对是广泛存在的“双伴侣分泌”途径的典型TpsA/TpsB系统，致力于在各种致病性和环境革兰氏阴性菌中运输长细胞外蛋白。FhaC属于普遍存在的蛋白质转运蛋白Omp85超家族。FhaC的x射线结构表明，假设作为fha传导孔的跨膜桶通道被TpsB转运体中保守的两个结构元件（n端螺旋和细胞外环）所阻碍。本研究提供了与FhaC分泌机制相关的构象动力学证据。利用顺磁电子共振、电生理学和体内方法，我们发现了FhaC在开放和封闭构象之间的交换。与其秘书伙伴FHA的相互作用改变了这种构象的分布。FhaC的开放构象意味着n端塞螺旋通道的大位移，在FHA分泌过程中保留在周质中。膜环境有利于TpsB转运体的动力学。
FhaC is an integral outer membrane protein of the whooping cough agent Bordetella pertussis that mediates the transport to the cell surface of a major virulence factor, the filamentous haemagglutinin adhesin FHA. The FHA/FhaC pair is a prototypic TpsA/TpsB system of the widespread Two-Partner Secretion' pathway, dedicated to the transport of long extracellular proteins in various pathogenic and environmental Gram-negative bacteria. FhaC belongs to the ubiquitous Omp85 superfamily of protein transporters. The X-ray structure of FhaC shows that the transmembrane -barrel channel hypothesized to serve as the FHA-conducting pore is obstructed by two structural elements conserved among TpsB transporters, an N-terminal helix and an extracellular loop. Here, we provide evidence for conformational dynamics of FhaC related to the secretion mechanism. Using paramagnetic electron resonance, electrophysiology and in vivo approaches, we showed that FhaC exchanges between open and closed conformations. The interaction with its secretory partner FHA alters this distribution of conformations. The open conformation of FhaC implies a large displacement from the channel of the N-terminal plug' helix, which remains in the periplasm during FHA secretion. The membrane environment favours the dynamics of the TpsB transporter.