2Y5Y

Crystal structure of LacY in complex with an affinity inactivator

Summary for 2Y5Y

• Entry DOI: 10.2210/pdb2y5y/pdb
• Related: 1PV6 1PV7 2CFP 2CFQ 2V8N
• Descriptor: LACTOSE PERMEASE, BARIUM ION, 2-sulfanylethyl beta-D-galactopyranoside (3 entities in total)
• Functional Keywords: transport protein, affinity inactivation
• Biological source: ESCHERICHIA COLI
• Cellular location: Cell inner membrane; Multi-pass membrane protein: P02920
• Total number of polymer chains: 2
• Total formula weight: 95298.17

Authors

Chaptal, V.,Kwon, S.,Sawaya, M.R.,Guan, L.,Kaback, H.R.,Abramson, J. (deposition date: 2011-01-19, release date: 2011-06-15, Last modification date: 2025-12-10)

Primary citation

Chaptal, V.,Kwon, S.,Sawaya, M.R.,Guan, L.,Kaback, H.R.,Abramson, J.
Crystal Structure of Lactose Permease in Complex with an Affinity Inactivator Yields Unique Insight Into Sugar Recognition.
Proc.Natl.Acad.Sci.USA, 108:9361-, 2011

PubMed 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.

PubMed: 21593407
DOI: 10.1073/PNAS.1105687108

Experimental method

X-RAY DIFFRACTION (3.38 Å)