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Assembly of an Evolutionarily New Pathway for α-Pyrone Biosynthesis in Arabidopsis

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Science  24 Aug 2012:
Vol. 337, Issue 6097, pp. 960-964
DOI: 10.1126/science.1221614

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Abstract

Plants possess arrays of functionally diverse specialized metabolites, many of which are distributed taxonomically. Here, we describe the evolution of a class of substituted α-pyrone metabolites in Arabidopsis, which we have named arabidopyrones. The biosynthesis of arabidopyrones requires a cytochrome P450 enzyme (CYP84A4) to generate the catechol-substituted substrate for an extradiol ring-cleavage dioxygenase (AtLigB). Unlike other ring-cleavage–derived plant metabolites made from tyrosine, arabidopyrones are instead derived from phenylalanine through the early steps of phenylpropanoid metabolism. Whereas CYP84A4, an Arabidopsis-specific paralog of the lignin-biosynthetic enzyme CYP84A1, has neofunctionalized relative to its ancestor, AtLigB homologs are widespread among land plants and many bacteria. This study exemplifies the rapid evolution of a biochemical pathway formed by the addition of a new biological activity into an existing metabolic infrastructure.

  • * Present address: Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.

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