Crystal structure of lactose permease in complex with an affinity inactivator yields unique insight into sugar recognition
- UCLA
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.
- Research Organization:
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
- Sponsoring Organization:
- NSFOTHERNIH
- OSTI ID:
- 1023667
- Journal Information:
- Proc. Natl. Acad. Sci. USA, Journal Name: Proc. Natl. Acad. Sci. USA Journal Issue: (23) ; 06, 2011 Vol. 108; ISSN PNASA6; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- ENGLISH
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