NMR structure and dynamics of the engineered fluorescein-binding lipocalin FluA reveal rigidification of beta-barrel and variable loops upon enthalpy-driven ligand binding.

ABSTRACT: The NMR structure of the 21 kDa lipocalin FluA, which was previously obtained by combinatorial design, elucidates a reshaped binding site specific for the dye fluorescein resulting from 21 side chain replacements with respect to the parental lipocalin, the naturally occurring bilin-binding protein (BBP). As expected, FluA exhibits the lipocalin fold of BBP, comprising eight antiparallel beta-strands forming a beta-barrel with an alpha-helix attached to its side. Comparison of the NMR structure of free FluA with the X-ray structures of BBP.biliverdin IX(gamma) and FluA.fluorescein complexes revealed significant conformational changes in the binding pocket, which is formed by four loops at the open end of the beta-barrel as well as adjoining beta-strand segments. An "induced fit" became appa

SUBMITTER: Mills JL 

PROVIDER: S-EPMC2860743 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature