2qys: Difference between revisions

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==Overview==

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.

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.

==About this Structure==

Line 13:

[[Category: Ocimum basilicum]]

[[Category: Single protein]]

[[Category: Bowman, M.E.]]

[[Category: Bowman, M E.]]

[[Category: Louie, G.V.]]

[[Category: Louie, G V.]]

[[Category: Noel, J.P.]]

[[Category: Noel, J P.]]

[[Category: eugenol]]

[[Category: phenylpropene]]

Line 22:

[[Category: short-chain dehydrogenase/reductase]]

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@@ Line 4: / Line 4: @@
 ==Overview==
-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.
+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.
 ==About this Structure==
@@ Line 13: / Line 13: @@
 [[Category: Ocimum basilicum]]
 [[Category: Single protein]]
-[[Category: Bowman, M.E.]]
+[[Category: Bowman, M E.]]
-[[Category: Louie, G.V.]]
+[[Category: Louie, G V.]]
-[[Category: Noel, J.P.]]
+[[Category: Noel, J P.]]
 [[Category: eugenol]]
 [[Category: phenylpropene]]
@@ Line 22: / Line 22: @@
 [[Category: short-chain dehydrogenase/reductase]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 11:08:19 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:43:18 2008''