Poster: Late and Moved Abstracts

Abs # 969: Expression profiling and functional definition of Arabidopsis CYP86A and CYP94B proteins as fatty acid hydroxylases

Presenter:	Duan, Hui , huiduan@uiuc.edu
Authors	Duan, Hui  (A)   Civjan, Natanya  (B)   Rupasinghe, Sangeewa  (A)   Sligar, Stephen  (B)   Schuler, Mary  (A)
Affiliations:	(A): Department of Cell and Structural Biology University of Illinois (B): Department of Biochemistry University of Illinois

Plants contain a significantly larger number of genes in their cytochrome P450 monooxygenase (CYP) superfamily than other eukaryotic systems (272 in Arabidopsis thaliana, 456 in rice, 56 in human, and 83 in Drosophila). But, the physiological and chemical functions have been defined for relatively few of the encoded proteins. In the Arabidopsis CYP86 and CYP94 cytochrome P450 families, only CYP86A1 and CYP86A8 have been functionally defined as fatty acid ω-hydroxylases. Fatty acid ω-hydroxylases have potential roles in the synthesis of cutin, production of signaling molecules and preventing accumulation of toxic levels of free fatty acids. To define function for the other members of the Arabidopsis CYP86A and CYP94B subfamilies, we have heterologously expressed each of them in baculovirus-infected Sf9 cells, shown that they ω-hydroxylate lauric acid (a prototype short chain fatty acids) and defined a range of long chain fatty acids capable of binding in the catalytic site of each of these enzymes. RT-PCR and microarray analyses have demonstrated very distinct regulation patterns for each of these fatty acid hydroxylases under normal growth conditions and in response to environmental stresses and chemical treatments. We will discuss the potential physiological functions of these fatty acid hydroxylases through a comparison of the regulation patterns with their predicted cis-acting regulatory elements and substrate specificities. Molecular models have been developed for a number of P450s whose substrate binding capacities have been defined by these approaches. We will also describe a Nanodisc system that enables the solubilization and incorporation of membrane-bound P450s and P450 reductases into nanobilayers suitable for sensitive substrate binding and turnover.