Crystallographic Structures of IlvN·Val/Ile Complexes: Conformational Selectivity for Feedback Inhibition of Aceto Hydroxy Acid Synthases.

ABSTRACT: Conformational factors that predicate selectivity for valine or isoleucine binding to IlvN leading to the regulation of aceto hydroxy acid synthase I (AHAS I) of Escherichia coli have been determined for the first time from high-resolution (1.9-2.43 Å) crystal structures of IlvN·Val and IlvN·Ile complexes. The valine and isoleucine ligand binding pockets are located at the dimer interface. In the IlvN·Ile complex, among residues in the binding pocket, the side chain of Cys⁴³ is 2-fold disordered (χ₁ angles of gauche^- and trans). Only one conformation can be observed for the identical residue in the IlvN·Val complexes. In a reversal, the side chain of His⁵³, located at the surface of the protein, exhibits two conformations in the IlvN·Val complex.

SUBMITTER: Bansal A 

PROVIDER: S-EPMC6668035 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature