Duan, Hui , Rupasinghe, Sanjeewa , Rodrigo, Iyoncy , Sandfort, Kara , Pan, Yinghong , Schuler, Mary A. .
Functional analyses of Arabidopsis fatty acid hydroxylases.
In plants, multiple forms of P450s catalyze in-chain and end-terminal hydroxylations and epoxidations of medium- and long-chain fatty acids. These are distributed throughout all kingdoms and in several distinct P450 families including the CYP86 and CYP94 families. Fatty acid hydroxylases are important in the synthesis of plant cuticles and signaling molecules and also for preventing the accumulation of high concentrations of free fatty acids. Multiple approaches have been used to define the functions of Arabidopsis thaliana fatty acid hydroxylases. First, we have cloned and optimized parameters for co-expression of ten CYP86 family and six CYP94 family proteins with P450 reductase in Sf9 insect cells. All expressed proteins were tested for their ability to bind a range of fatty acids including unsubstituted (C12:0 to C18:0, C18:1, C18:2, C18:3) and oxygenated (9,10-epoxystearic acid, 9,10-dihydroxystearic acid). Second, using molecular modeling and substrate-docking procedures, we have detailed constraints in the catalytic sites of these proteins that limit their substrate preferences. Finally, we have detailed the biotic and abiotic stress responses of nine Arabidopsis T-DNA knockout lines containing insertions in these loci. Among other findings, these approaches have identified several MeJ and BION-inducible CYP94 proteins mediating hydroxylations on oxygenated fatty acids that have potential to act as stress signaling molecules. Knockout lines inactivated in these loci display a range of susceptibilities to bacterial pathogens and insect predators. These results and others obtained for members of the CYP86 family are elucidating the physiological functions of fatty acid hydroxylases in Arabidopsis.
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1 - University of Illinois Urbana-Champaign, Cell and Developmental biology, Urbana, IL, 61801
2 - University of Illinois Urbana-Champaign, Biochemistry
3 - University of Illinois Urbana-Champaign, Cell and Developmental Biology
4 - University of Illinois Urbana-Champaign, Plant Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM