Structure of 1-aminocyclopropane-1-carboxylate synthase in complex with an amino-oxy analogue of the substrate:: implications for substrate binding

The crystal structure of 1-aminocyclopropane-1-carboxylate (ACC) synthase in complex with the substrate analogue [2-(aminooxy)ethyl](5'-deoxyadenosin-5'-yl)(methyl)sulfonium (AMA) was determined at 2.01-Angstrom resolution. The crystallographic results show that a covalent adduct (oxime) is formed between AMA (an amino-oxy analogue of the natural substrate S-adenosyl-L-methionine (SAM)) and the pyridoxal 5'-phosphate (PLP) cofactor of ACC synthase. The oxime formation is supported by spectroscopic data. The ACC synthase-AMA structure provides reliable and detailed information on the binding mode of the natural substrate of ACC synthase and complements previous structural and functional work on this enzyme. (C) 2003 Elsevier Science B.V. All rights reserved.