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The multiple phenylpropene synthases in both Clarkia breweri and Petunia hybrida represent two distinct protein lineages
Author(s) -
Koeduka Takao,
Louie Gordon V.,
Orlova Irina,
Kish Christine M.,
Ibdah Mwafaq,
Wilkerson Curtis G.,
Bowman Marianne E.,
Baiga Thomas J.,
Noel Joseph P.,
Dudareva Natalia,
Pichersky Eran
Publication year - 2008
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2008.03412.x
Subject(s) - isoeugenol , eugenol , petunia , biology , coniferyl alcohol , biochemistry , phenylpropanoid , botany , enzyme , chemistry , biosynthesis , organic chemistry , gene
Summary Many plants synthesize the volatile phenylpropene compounds eugenol and isoeugenol to serve in defense against herbivores and pathogens and to attract pollinators. Clarkia breweri flowers emit a mixture of eugenol and isoeugenol, while Petunia hybrida flowers emit mostly isoeugenol with small amounts of eugenol. We recently reported the identification of a petunia enzyme, isoeugenol synthase 1 (PhIGS1) that catalyzes the formation of isoeugenol, and an Ocimum basilicum (basil) enzyme, eugenol synthase 1 (ObEGS1), that produces eugenol. ObEGS1 and PhIGS1 both utilize coniferyl acetate, are 52% sequence identical, and belong to a family of NADPH‐dependent reductases involved in secondary metabolism. Here we show that C. breweri flowers have two closely related proteins (96% identity), CbIGS1 and CbEGS1, that are similar to ObEGS1 (58% and 59% identity, respectively) and catalyze the formation of isoeugenol and eugenol, respectively. In vitro mutagenesis experiments demonstrate that substitution of only a single residue can substantially affect the product specificity of these enzymes. A third C. breweri enzyme identified, CbEGS2, also catalyzes the formation of eugenol from coniferyl acetate and is only 46% identical to CbIGS1 and CbEGS1 but more similar (>70%) to other types of reductases. We also found that petunia flowers contain an enzyme, PhEGS1, that is highly similar to CbEGS2 (82% identity) and that converts coniferyl acetate to eugenol. Our results indicate that plant enzymes with EGS and IGS activities have arisen multiple times and in different protein lineages.