一種核黃素(維生素 B2)膜運(yùn)輸因子（重要能量耦合因子(ECF)家族的一個(gè)成員）的X-射線(xiàn)晶體結(jié)構(gòu)已被確定。來(lái)自金黃葡萄球菌的運(yùn)輸因子的“膜嵌入基質(zhì)結(jié)合域”的結(jié)構(gòu)顯示了一個(gè)以前沒(méi)有報(bào)道過(guò)的折疊，其中核黃素分子結(jié)合在一個(gè)環(huán)及幾個(gè)跨膜片段的周質(zhì)部分上,。（生物谷Bioon.com）
生物谷推薦原文出處：
Nature doi:10.1038/nature09488
Structure and mechanism of the S component of a bacterial ECF transporter
Peng Zhang1, Jiawei Wang2 & Yigong Shi3
1.Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, New Jersey 08544, USA
2.State Key Laboratory of Biomembrane and Membrane Biotechnology, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
3.Ministry of Education Protein Science Laboratory, Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
Top of pageAbstractThe energy-coupling factor (ECF) transporters, responsible for vitamin uptake in prokaryotes, are a unique family of membrane transporters1, 2. Each ECF transporter contains a membrane-embedded, substrate-binding protein (known as the S component), an energy-coupling module that comprises two ATP-binding proteins (known as the A and A′ components) and a transmembrane protein (known as the T component). The structure and transport mechanism of the ECF family remain unknown. Here we report the crystal structure of RibU, the S component of the ECF-type riboflavin transporter from Staphylococcus aureus at 3.6-? resolution. RibU contains six transmembrane segments, adopts a previously unreported transporter fold and contains a riboflavin molecule bound to the L1 loop and the periplasmic portion of transmembrane segments 4–6. Structural analysis reveals the essential ligand-binding residues, identifies the putative transport path and, with sequence alignment, uncovers conserved structural features and suggests potential mechanisms of action among the ECF transporters.
