PDBsum entry 4zir

Transport protein, hydrolase/inhibitor

PDB id: 4zir

Contents

Protein chains

263 a.a.

247 a.a.

Ligands

ANP ×2

Metals

_MG ×2

_CL ×3

Waters ×20

References listed in PDB file

Key reference

• Title: Atp binding drives substrate capture in an ecf transporter by a release-And-Catch mechanism.
• Authors: N.K.Karpowich, J.M.Song, N.Cocco, D.N.Wang.
• Ref.: Nat Struct Biol, 2015, 22, 565-571. [DOI no: 10.1038/nsmb.3040]
• PubMed id: 26052893

Abstract

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 found 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.