PMID:20173761
| Citation |
Lewinson, O, Lee, AT, Locher, KP and Rees, DC (2010) A distinct mechanism for the ABC transporter BtuCD-BtuF revealed by the dynamics of complex formation. Nat. Struct. Mol. Biol. 17:332-8 |
|---|---|
| Abstract |
ATP-binding cassette (ABC) transporters are integral membrane proteins that translocate a diverse array of substrates across cell membranes. We present here the dynamics of complex formation of three structurally characterized ABC transporters-the BtuCD vitamin B(12) importer and MetNI d/l-methionine importer from Escherichia coli and the Hi1470/1 metal-chelate importer from Haemophilus influenzae-in complex with their cognate binding proteins. Similarly to other ABC importers, MetNI interacts with its binding protein with low affinity (K(d) approximately 10(-4) M). In contrast, BtuCD-BtuF and Hi1470/1-Hi1472 form stable, high-affinity complexes (K(d) approximately 10(-13) and 10(-9) M, respectively). In BtuCD-BtuF, vitamin B(12) accelerates the complex dissociation rate approximately 10(7)-fold, with ATP having an additional destabilizing effect. The findings presented here highlight substantial mechanistic differences between BtuCD-BtuF, and likely Hi1470/1-Hi1472, and the better-characterized maltose and related ABC transport systems, indicating that there is considerable mechanistic diversity within this large protein super-family. |
| Links |
PubMed PMC2924745 Online version:10.1038/nsmb.1770 |
| Keywords |
ATP-Binding Cassette Transporters/metabolism; Bacterial Proteins/metabolism; Biological Transport/physiology; Chromatography, Gel; Escherichia coli Proteins/metabolism; Kinetics; Periplasmic Binding Proteins/metabolism; Protein Binding; Thermodynamics; Vitamin B 12/metabolism |
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