Fatty Acid Synthase from Arabidopsis thaliana and Related Plants

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9405588 Jaworski Fatty acid biosynthesis in plants is a primary metabolic pathway that is necessary to provide the fatty acyl components found in the lipids of membranes and in vegetable oils. In our laboratory, the discovery of 3-ketoacyl-acyl carrier protein (ACP) synthase III (KAS III) activity has led to new questions about regulation of fatty acid formation. We have shown that KAS III is the predominant mechanism at the start of fatty acid synthesis, but is it a required step? To answer this question, we will: (1) analyze the effect of altered KAS III activity in Arabidopsis thaliana and other plants. KAS III expression will be both increased and decreased in Arabidopsis with antisence and sense constructs of its cDNA; (2) attempt to identify other KASs and analyze their roles in synthesis of medium chain fatty acids; and (3) we will determine if KAS III is capable of interacting with other enzymes of fatty acid synthase function under in vivo conditions, using a 'two-hybrid' system to detect protein-protein interaction. %%% Fatty acid biosynthesis in plants is a primary metabolic pathway that is necessary to provide the fatty acyl components found in the lipids of membranes and in vegetable oils. Areas under study are intended to answer basic questions concerning the regulation and contribution of individual reactions to this essential pathway. In addition, a study will be initiated to probe questions concerning the molecular organization of this pathway. What are the basic reactions of fatty acid biosynthesis in plants and how are they controlled? It has been demonstrated by this laboratory that a reaction caused by the enzyme 3-ketoacyl-acyl carrier protein synthase, or KAS III, is the predominant route for beginning the process of fatty acid synthesis. But whether this in a required reaction has not been proved. One approach to find an answer is to study how KAS III operates inside the cell during fatty acid formation. It appears that many of t he enzymes that are involved in fatty acid formation group together and form large, operational complexes. As a result, it is believed that the essential role for KAS III, or other KAS-type enzymes, in fatty acid formation will become clearer if these enzymes also associate themselves in the same fatty acid producing enzyme aggregations. ***