ATP binding drives substrate capture in an ECF transporter by a release-and-catch mechanism.
ATP binding drives substrate capture in an ECF transporter by a release-and-catch mechanism.
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DOI：
10.1038/nsmb.3040
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发表时间：
2015-07
影响因子：
16.8
通讯作者：
Wang DN
中科院分区：
文献类型：
--
作者：
Karpowich NK;Song JM;Cocco N;Wang DN
ECF转运蛋白是维生素的活性转运蛋白家族。它由四个亚基组成：一个膜包埋底物结合亚基（EcfS），一个跨膜偶联亚基（EcfT）和两个ATP结合盒ATP酶（EcfA和EcfA′）。我们已经研究了从病原体单核细胞增生李斯特菌，LmECF-RibU的核黄素的ECF转运体的机制。利用结构和生物化学方法，我们发现ATP结合到EcfAA′ ATP酶驱动构象变化，使S亚基从EcfAA′T ECF模块中解离。在从ECF模块释放后，RibU S亚基然后结合核黄素转运底物。我们还发现不同底物的S亚基竞争ECF模块的ATP结合状态。我们的研究结果解释了ECF转运蛋白如何捕获转运底物，并重现了该家族命名的S亚基竞争的体内观察结果。
ECF transporters are a family of active transporters for vitamins. They are composed of four subunits: a membrane-embedded substrate-binding subunit (EcfS), a transmembrane coupling subunit (EcfT), and two ATP-binding cassette ATPases (EcfA and EcfA′). We have investigated the mechanism of the ECF transporter for riboflavin from the pathogen Listeria monocytogenes, LmECF–RibU. Using structural and biochemical approaches we find that ATP binding to the EcfAA′ ATPases drives a conformational change that dissociates the S subunit from the EcfAA′T ECF module. Upon release from the ECF module, the RibU S subunit then binds the riboflavin transport substrate. We also find that S subunits for distinct substrates compete for the ATP-bound state of the ECF module. Our results explain how ECF transporters capture the transport substrate and reproduce the in vivo observations on S subunit competition for which the family was named.