ECF (Energy-coupling factor)转运蛋白属于一类新型ABC 转运蛋白，在生物体中负责多种维生素和微量元素的跨膜运输。ECF转运蛋白由细胞膜上特异性结合底物的EcfS和负责能量耦联的EcfT及胞内结合与分解ATP的EcfA/A’组成， EcfT和EcfA/A’被称为能量耦合模块或ECF模块。ECF转运蛋白家族分为ECF模块专有型和共享型两类，ECF模块专有型转运蛋白在组成成分、底物结合、转运方式上与共享型有着显著的差异。近几年，包括我们在内的研究者对ECF模块共享型转运蛋白的结构与跨膜转运机制开展了比较系统的研究工作。然而，人们目前对ECF模块专有型转运蛋白复合体的结构与机制却并不了解。本研究将通过解析能量耦合模块专有型ECF转运蛋白复合体的结构，并开展其底物结合蛋白EcfS的活性和转运过程的动态分析，揭示能量耦合模块专有型ECF转运蛋白结合和跨膜转运底物的分子机制。

ECF (Energy-coupling factor) transporters are a new class of ABC transporters, which are responsible for the uptake of vitamins and micronutrients in living organisms. Each ECF transporter is comprised of four different components, namely the transmembrane EcfT protein which together with the cytoplasmic nucleotide-binding proteins EcfA and EcfA’ constitute the energy coupling module, and another transmembrane EcfS protein which is responsible for substrate-specific binding. The ECF transporters are classified into two groups: those encoded by linked genes for ecfS and an ecfS-specific ecfA-ecfA’-ecfT module (group-I), and those with a common ecfA-ecfA’-ecfT module shared by several different EcfS proteins in the same organism (group-II). In the past several years, a number of studies including those from our lab have been performed to elucidate the structure and mechanism of group-II ECF transporters. However, the underlying molecular mechanism of group-I ECF transporters remains elusive, since the group-I ECF transporters differ in the complex constitution, substrate binding and transport from those of group-II transporters. In this project, we plan to investigate the structural mechanism of group-I ECF transporters through structure determination and structural based mutational analysis combining with biophysical dynamic analysis of the transport process.