Campus Units
Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of
Document Type
Article
Publication Version
Accepted Manuscript
Publication Date
1-2011
Journal or Book Title
The Plant Journal
Volume
65
Issue
1
First Page
87
Last Page
95
DOI
10.1111/j.1365-313X.2010.04408.x
Abstract
Rice (Oryza sativa) produces momilactone diterpenoids as both phytoalexins and allelochemicals. Strikingly, the rice genome contains a biosynthetic gene cluster for momilactone production, located on rice chromosome 4, which contains two cytochromes P450 mono-oxygenases, CYP99A2 and CYP99A3, with undefined roles; although it has been previously shown that RNAi double knock-down of this pair of closely related CYP reduced momilactone accumulation. Here we attempted biochemical characterization of CYP99A2 and CYP99A3, which ultimately was achieved by complete gene recoding, enabling functional recombinant expression in bacteria. With these synthetic gene constructs it was possible to demonstrate that, while CYP99A2 does not exhibit significant activity with diterpene substrates, CYP99A3 catalyzes consecutive oxidations of the C19 methyl group of the momilactone precursor syn-pimara-7,15-diene to form, sequentially, syn-pimaradien-19-ol, syn-pimaradien-19-al and syn-pimaradien-19-oic acid. These are presumably intermediates in momilactone biosynthesis, as a C19 carboxylic acid moiety is required for formation of the core 19,6-γ-lactone ring structure. We further were able to detect syn-pimaradien-19-oic acid in rice plants, which indicates physiological relevance for the observed activity of CYP99A3. In addition, we found that CYP99A3 also oxidized synstemod- 13(17)-ene at C19 to produce, sequentially, syn-stemoden-19-ol, syn-stemoden-19-al and syn-stemoden-19-oic acid, albeit with lower catalytic efficiency than with syn-pimaradiene. Although the CYP99A3 syn-stemodene derived products were not detected in planta, these results nevertheless provide a hint at the currently unknown metabolic fate of this diterpene in rice. Regardless of any wider role, our results strongly indicate that CYP99A3 acts as a multifunctional diterpene oxidase in momilactone biosynthesis.
Copyright Owner
The Authors
Copyright Date
2010
Language
en
File Format
application/pdf
Recommended Citation
Wang, Qiang; Hillwig, Matthew L.; and Peters, Reuben J., "CYP99A3: functional identification of a diterpene oxidase from the momilactone biosynthetic gene cluster in rice" (2011). Biochemistry, Biophysics and Molecular Biology Publications. 101.
https://lib.dr.iastate.edu/bbmb_ag_pubs/101
Included in
Agronomy and Crop Sciences Commons, Biochemistry, Biophysics, and Structural Biology Commons, Plant Breeding and Genetics Commons
Comments
This is the peer reviewed version of the following article: Wang, Q., Hillwig, M. L. and Peters, R. J. (2011), CYP99A3: functional identification of a diterpene oxidase from the momilactone biosynthetic gene cluster in rice. The Plant Journal, 65: 87–95, which has been published in final form at doi: 10.1111/j.1365-313X.2010.04408.x. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.