PDBsum entry 2qw8

Oxidoreductase

PDB id: 2qw8

Contents

Protein chains

310 a.a. *

Ligands

NO3

NAP ×2

PEG

Waters ×472

* Residue conservation analysis

PDB id:

2qw8

Name:

Oxidoreductase

Title:

Structure of eugenol synthase from ocimum basilicum

Structure:

Eugenol synthase 1. Chain: a, b. Engineered: yes

Source:

Ocimum basilicum. Sweet basil. Gene: egs1. Expressed in: escherichia coli.

Resolution:

1.60Å R-factor: 0.205 R-free: 0.226

Authors:

G.V.Louie,J.P.Noel

Key ref:

G.V.Louie et al. (2007). Structure and reaction mechanism of basil eugenol synthase. Plos One, 2, e993. PubMed id: 17912370

Date:

09-Aug-07 Release date: 10-Jun-08

Protein chains

Q15GI4  (EGS1_OCIBA) -  Eugenol synthase 1 from Ocimum basilicum

Seq: 314 a.a.

Struc: 310 a.a.

Enzyme reactions

• Enzyme class: E.C.1.1.1.318 - eugenol synthase.
• Reaction: eugenol + a carboxylate + NADP⁺ = a coniferyl ester + NADPH

eugenol + carboxylate + NADP(+) (Bound ligand (Het Group name = NAP) corresponds exactly) = coniferyl ester + NADPH

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

Plos One 2:e993 (2007)

PubMed id: 17912370

Structure and reaction mechanism of basil eugenol synthase.

G.V.Louie, T.J.Baiga, M.E.Bowman, T.Koeduka, J.H.Taylor, S.M.Spassova, E.Pichersky, J.P.Noel.

ABSTRACT

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 side-chain amino moiety of a conserved lysine residue, Lys132. The C4 carbon of nicotinamide resides immediately adjacent to the site of hydride addition, the C7 carbon of cinnamyl acetate substrates. The inhibitor-bound EGS structure suggests a two-step reaction mechanism involving the formation of a quinone-methide prior to reduction. The formation of this intermediate is promoted by a hydrogen-bonding network that favors deprotonation of the substrate's 4-hydroxyl group and disfavors binding of the acetate moiety, akin to a push-pull catalytic mechanism. Notably, the catalytic involvement in EGS of the conserved Lys132 in preparing the phenolic substrate for quinone methide formation through the proton-relay network appears to be an adaptation of the analogous role in hydrogen bonding played by the equivalent lysine residue in other enzymes of the SDR family.