5JSZ: Folate Ecf Transporter: Apo State

Energy-coupling factor (ECF) transporters mediate uptake of micronutrients in prokaryotes. The transporters consist of an S-component that binds the transported substrate and an ECF module (EcfAA'T) that binds and hydrolyses ATP. The mechanism of transport is poorly understood but presumably involves an unusual step in which the membrane-embedded S-component topples over to carry the substrate across the membrane. In many ECF transporters, the S-component dissociates from the ECF module after transport. Subsequently, substrate-bound S-components out-compete the empty proteins for re-binding to the ECF module in a new round of transport. Here we present crystal structures of the folate-specific transporter ECF-FolT from Lactobacillus delbrueckii. Interaction of the ECF module with FolT stabilizes the toppled state, and simultaneously destroys the high-affinity folate-binding site, allowing substrate release into the cytosol. We hypothesize that differences in the kinetics of toppling can explain how substrate-loaded FolT out-competes apo-FolT for association with the ECF module.
PDB ID: 5JSZDownload
MMDB ID: 139419
PDB Deposition Date: 2016/5/9
Updated in MMDB: 2016/06
Experimental Method:
x-ray diffraction
Resolution: 3  Å
Source Organism:
Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 = JCM 1002
Similar Structures:
Biological Unit for 5JSZ: tetrameric; determined by author and by software (PISA)
Molecular Components in 5JSZ
Label Count Molecule
Proteins (4 molecules)
Energy-coupling Factor Transporter Atp-binding Protein Ecfa1(Gene symbol: LDB_RS01805)
Molecule annotation
Energy-coupling Factor Transporter Atp-binding Protein Ecfa2(Gene symbol: LDB_RS01810)
Molecule annotation
Conserved Hypothetical Membrane Protein
Molecule annotation
Energy-coupling Factor Transporter Transmembrane Protein Ecft
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB