Substrate-Induced Conformational Changes in the S-Component ThiT from an Energy Coupling Factor Transporter

Autor(en): Majsnerowska, Maria
Hanelt, Inga
Wunnicke, Dorith
Schaefer, Lars V.
Steinhoff, Heinz-Juergen 
Slotboom, Dirk Jan
Stichwörter: BILAYER; BINDING; Biochemistry & Molecular Biology; Biophysics; Cell Biology; EXPRESSION; FORCE-FIELDS; HOMOLOG; LINCS; LINEAR CONSTRAINT SOLVER; MECHANISM; MOLECULAR-DYNAMICS SIMULATIONS; PROTEINS
Erscheinungsdatum: 2013
Herausgeber: CELL PRESS
Journal: STRUCTURE
Volumen: 21
Ausgabe: 5
Startseite: 861
Seitenende: 867
Zusammenfassung: 
Energy coupling factor (ECF) transporters are a recently discovered class of ABC transporters that mediate vitamin uptake in prokaryotes. Characteristic for ECF-type ABC transporters are small integral membrane proteins (S-components) that bind the transported substrates with high affinity. S-components associate with a second membrane protein (EcfT) and two peripheral ATPases to form a complete ATP-dependent transporter. Here, we have used EPR spectroscopy, stopped-flow fluorescence spectroscopy, and molecular dynamics simulations to determine the structural rearrangements that take place in the S-component ThiT from Lactococcus lactis upon binding of thiamin. Thiamin-induced conformational changes were confined to the long and partially membrane-embedded loop between transmembrane helices 1 and 2 that acts as a lid to occlude the binding site. The results indicate that solitary ThiT functions as a bona fide high-affinity substrate binding protein, which lacks a translocation pathway within the protein.
ISSN: 09692126
DOI: 10.1016/j.str.2013.03.007

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