Direct sugar binding to LacY measured by resonance energy transfer.

ABSTRACT: Trp151 in the lactose permease of Escherichia coli (LacY) is an important component of the sugar-binding site and the only Trp residue out of six that is in close proximity to the galactopyranoside in the structure (1PV7). The short distance between Trp151 and the sugar is favorable for Förster resonance energy transfer (FRET) to nitrophenyl or dansyl derivatives with the fluorophore at the anomeric position of galactose. Modeling of 4-nitrophenyl-alpha-d-galactopyranoside (alpha-NPG) in the binding-site of LacY places the nitrophenyl moiety about 12 A away from Trp151, a distance commensurate with the Förster distance for a Trp-nitrobenzoyl pair. We demonstrate here that alpha-NPG binding to LacY containing all six native Trp residues causes galactopyranoside-specific FRET from Trp151. Mo

SUBMITTER: Smirnova IN 

PROVIDER: S-EPMC2566955 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature