Arabidopsis Camelliol C Synthase Evolved from Enzymes That Make Pentacycles

Org. Lett., 9 (25), 5223 -5226, 2007. 10.1021/ol702399g S1523-7060(70)02399-4
Web Release Date: November 7, 2007

Arabidopsis Camelliol C Synthase Evolved from Enzymes That Make Pentacycles

Mariya D. Kolesnikova, William K. Wilson, David A. Lynch, Allie C. Obermeyer, and Seiichi P. T. Matsuda*

Department of Chemistry and Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005

matsuda@rice.edu

Received October 2, 2007

Abstract:

We establish by heterologous expression that the Arabidopsis thaliana oxidosqualene cyclase At1g78955 (CAMS1) makes camelliol C (98%), achilleol A (2%), and

-amyrin (0.2%). CAMS1 is the first characterized cyclase that generates predominantly a monocyclic triterpene alcohol. Phylogenetic analysis shows that CAMS1 evolved from enzymes that make pentacycles, thus revealing that its pentacyclic

-amyrin byproduct is an evolutionary relic. Sequence alignments support prior suggestions that decreased steric bulk at a key active-site residue promotes monocycle formation.

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