PMID:21593407
| Citation |
Chaptal, V, Kwon, S, Sawaya, MR, Guan, L, Kaback, HR and Abramson, J (2011) Crystal structure of lactose permease in complex with an affinity inactivator yields unique insight into sugar recognition. Proc. Natl. Acad. Sci. U.S.A. 108:9361-6 |
|---|---|
| Abstract |
Lactose permease of Escherichia coli (LacY) with a single-Cys residue in place of A122 (helix IV) transports galactopyranosides and is specifically inactivated by methanethiosulfonyl-galactopyranosides (MTS-gal), which behave as unique suicide substrates. In order to study the mechanism of inactivation more precisely, we solved the structure of single-Cys122 LacY in complex with covalently bound MTS-gal. This structure exhibits an inward-facing conformation similar to that observed previously with a slight narrowing of the cytoplasmic cavity. MTS-gal is bound covalently, forming a disulfide bond with C122 and positioned between R144 and W151. E269, a residue essential for binding, coordinates the C-4 hydroxyl of the galactopyranoside moiety. The location of the sugar is in accord with many biochemical studies. |
| Links |
PubMed PMC3111295 Online version:10.1073/pnas.1105687108 |
| Keywords |
Amino Acid Substitution; Binding Sites/genetics; Biological Transport; Crystallization; Cysteine/chemistry; Cysteine/genetics; Cysteine/metabolism; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Galactose/chemistry; Galactose/metabolism; Lactose/chemistry; Lactose/metabolism; Membrane Transport Proteins/chemistry; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism; Mesylates/chemistry; Mesylates/metabolism; Models, Molecular; Monosaccharide Transport Proteins/chemistry; Monosaccharide Transport Proteins/genetics; Monosaccharide Transport Proteins/metabolism; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Substrate Specificity; Symporters/chemistry; Symporters/genetics; Symporters/metabolism; X-Ray Diffraction |
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