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:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- NSFOTHERNIH
- OSTI ID:
- 1023667
- Journal Information:
- Proc. Natl. Acad. Sci. USA, Vol. 108, Issue (23) ; 06, 2011; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
A five-residue sequence near the carboxyl terminus of the polytopic membrane protein lac permease is required for stability within the membrane
Structure and function of the mannitol permease of the Escherichia coli phosphotransferase sugar transport system