4HUQ

Crystal Structure of a transporter

4HUQ の概要

• エントリーDOI: 10.2210/pdb4huq/pdb
• 分子名称: Energy-coupling factor transporter ATP-binding protein EcfA 1, Energy-coupling factor transporter ATP-binding protein EcfA 2, Uncharacterized protein, ... (5 entities in total)
• 機能のキーワード: transporter, hydrolase
• 由来する生物種: Lactobacillus brevis; 詳細
• 細胞内の位置: Cell membrane; Peripheral membrane protein (By similarity): Q03PY6 Q03PY5; Cell membrane; Multi-pass membrane protein (Potential): Q03PY7
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 114128.33

構造登録者

Zhang, P.,Xu, K.,Zhang, M.,Zhao, Q.,Yu, F. (登録日: 2012-11-03, 公開日: 2013-04-17, 最終更新日: 2024-02-28)

主引用文献

Xu, K.,Zhang, M.,Zhao, Q.,Yu, F.,Guo, H.,Wang, C.,He, F.,Ding, J.,Zhang, P.
Crystal structure of a folate energy-coupling factor transporter from Lactobacillus brevis.
Nature, 497:268-271, 2013

PubMed Abstract: ATP-binding cassette (ABC) transporters, composed of importers and exporters, form one of the biggest protein superfamilies that transport a variety of substrates across the membrane, powered by ATP hydrolysis. Most ABC transporters are composed of two transmembrane domains and two cytoplasmic nucleotide-binding domains. Also, importers from prokaryotes usually have extra solute-binding proteins in the periplasm that are responsible for the binding of substrates. Structures of importers have been reported that suggested a two-state model for the transport mechanism. Energy-coupling factor (ECF) transporters belong to a new class of ATP-binding cassette importers. Each ECF transporter comprises an energy-coupling module consisting of a transmembrane T protein (EcfT), two nucleotide-binding proteins (EcfA and EcfA'), and another transmembrane substrate-specific binding S protein (EcfS). Despite the similarities with ABC transporters, ECF transporters have different organizational and functional properties. The lack of solute-binding proteins in ECF transporters differentiates them clearly from the canonical ABC importers. Previously reported structures of the EcfS proteins RibU and ThiT clearly demonstrated the binding site of substrate riboflavin and thiamine, respectively. However, the organization of the four different components and the transport mechanism of ECF transporters remain unknown. Here we present the structure of an intact folate ECF transporter from Lactobacillus brevis at a resolution of 3 Å. This structure was captured in an inward-facing, nucleotide-free conformation with no bound substrate. The folate-binding protein FolT is nearly parallel to the membrane and is bound almost entirely by EcfT, which adopts an L shape and connects to EcfA and EcfA' through two coupling helices. Two conserved XRX motifs from the coupling helices of EcfT have a vital role in energy coupling by docking into EcfA-EcfA'. We propose a transport model that involves a substantial conformational change of FolT.

PubMed: 23584589
DOI: 10.1038/nature12046

実験手法

X-RAY DIFFRACTION (2.998 Å)