The Cytochrome P450 CYP86A22 Is a Fatty Acyl-CoA Ï-Hydroxylase Essential for Estolide Synthesis in the Stigma of Petunia hybrida
The stigmatic estolide is a lipid-based polyester constituting the major component of exudate in solanaceous plants. Although the exudate is believed to play important roles in the pollination process, the biosynthetic pathway of stigmatic estolide, including genes encoding the key enzymes, remains...
Saved in:
Published in | The Journal of biological chemistry Vol. 285; no. 6; p. 3986 |
---|---|
Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society for Biochemistry and Molecular Biology
05.02.2010
|
Online Access | Get full text |
Cover
Loading…
Summary: | The stigmatic estolide is a lipid-based polyester constituting the major component of exudate in solanaceous plants. Although
the exudate is believed to play important roles in the pollination process, the biosynthetic pathway of stigmatic estolide,
including genes encoding the key enzymes, remains unknown. Here we report the cloning and characterization of the cytochrome
P450 gene CYP86A22 , which encodes a fatty acyl-CoA Ï-hydroxylase involved in estolide biosynthesis in the stigma of Petunia hybrida . A CYP86A22 cDNA was isolated from a developing stigma cDNA library, and the corresponding gene was shown to express predominantly in
the developing stigma. Among six P450 genes isolated from this library, only CYP86A22 was implicated in Ï-hydroxylation following RNA interference (RNAi)-mediated suppression. Unlike wild-type plants in which
Ï-hydroxy fatty acids (mainly in the form of 18-hydroxy oleic acid and 18-hydroxy linoleic acid) compose 96% of total stigma
fatty acids, the Ï-hydroxy fatty acids were essentially absent in the stigmas from 18 of 46 CYP86A22 -RNAi transgenic plants and had varying levels of suppression in the remaining 28 plants. Furthermore, lipids in the 18 CYP86A22 -RNAi stigmas were predominantly triacylglycerols and diacylglycerols instead of the estolides, which characterize the wild-type
stigma. Analyses of recombinant CYP86A22 conclusively demonstrated that this P450 is a Ï-hydroxylase with a substrate preference
for both saturated and unsaturated acyl-CoAs rather than free fatty acids. We conclude that the cytochrome P450 enzyme CYP86A22
is the key fatty acyl-CoA Ï-hydroxylase essential for the production of Ï-hydroxy fatty acids and the biosynthesis of triacylglycerol-/diacylglycerol-based
estolide polyesters in the petunia stigma. |
---|---|
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M109.050765 |