Structural constraints on the ternary complex of 5-enolpyruvylshikimate-3-phosphate synthase from rotational-echo double-resonance NMR

The 46 kDa enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase catalyzes the condensation of shikimate-3-phosphate (S3P) and phosphoenolpyruvate to form EPSP. The reaction is inhibited by N-(phosphonomethyl)-glycine (Glp), which, in the presence of S3P, binds to EPSP synthase to form a stable ternary complex. As part of a solid-state NMR characterization of this structure, N-15 labels were introduced selectively into the lysine, arginine and histidine residues of EPSP synthase and distances to a C-13 label in Glp and to the P-31 in S3P and Glp were measured by rotational-echo double-resonance NMR. Three lysine and four arginine residues are in the proximity of the phosphate group of S3P and the carboxyl and phosphonate groups of Glp. A single histidine residue is in the vicinity of the binding site (closer to Glp than to S3P) but is more distant than the lysine and arginine residues. (C) 1996 Academic Press Limited.