structure and reaction mechanism of basil eugenol synthase罗勒丁香酚合酶的结构和反应机理.pdfVIP

Structure and Reaction Mechanism of Basil Eugenol Synthase 1 1 1 2 1 1 2 Gordon V. Louie , Thomas J. Baiga , Marianne E. Bowman , Takao Koeduka , John H. Taylor , Snejina M. Spassova , Eran Pichersky , Joseph P. Noel1* 1 Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California, United States of America, 2 Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America Phenylpropenes, a large group of plant volatile compounds that serve in multiple roles in defense and pollinator attraction, contain a propenyl side chain. Eugenol synthase (EGS) catalyzes the reductive displacement of acetate from the propenyl side chain of the substrate coniferyl acetate to produce the allyl-phenylpropene eugenol. We report here the structure determination of EGS from basil (Ocimum basilicum) by protein x-ray crystallography. EGS is structurally related to the short- chain dehydrogenase/reductases (SDRs), and in particular, enzymes in the isoflavone-reductase-like subfamily. The structure of a ternary complex of EGS bound to the cofactor NADP(H) and a mixed competitive inhibitor EMDF ((7S,8S)-ethyl (7,8- methylene)-dihydroferulate) provides a detailed view of the binding interactions within the EGS active site and a starting point for mutagenic examination of the unusual reductive mechanism of EGS. The key interactions between EMDF and the EGS- holoenzyme include stacking of the phenyl ring of EMDF against the cofactor’s nicotinamide ring and a water-mediated hydrogen-bonding interaction between the EMDF 4-hydroxy group and the s