|Nanayakkara, Dhammika - UNIVERSITY OF MISSISSIPPI|
Submitted to: American Chemical Society Symposium Series
Publication Type: Book / Chapter
Publication Acceptance Date: December 30, 2005
Publication Date: January 20, 2007
Citation: Cook, D., Dayan, F.E., Rimando, A.M., Nanayakkara, D., Pan, Z., Duke, S.O., Baerson, S.R. 2007. Molecular and Biochemical Characterization of Novel Polyketide Synthases Likely To Be Involved in the Biosynthesis of Sorgoleone. American Chemical Society Symposium Series. 955:141-151. Interpretive Summary: This is a meeting proceedings/symposium publication and no interpretive summary is required.
Technical Abstract: Sorgoleone, an oily exudate secreted from the root hairs of sorghum (Sorghum bicolor (L.) Moench), acts as a potent allelochemical. Its phytotoxic properties make the elucidation of the biosynthetic enzymes participating in this pathway desirable. Previous studies suggest that the biosynthetic pathway of sorgoleone involves a polyketide synthase as well as a fatty acid desaturase, an O-methyl transferase, and a cytochrome P450 monooxygenase. This polyketide synthase is proposed to use a novel long chain fatty acyl-CoA (C16:3) as a starter unit and catalyzes three iterative condensation reactions using malonyl-CoA to form a transient linear tetraketide that cyclizes to form a pentadecatriene resorcinol. To identify the polyketide synthase gene(s) involved in the biosynthesis of these alkylresorcinols, a root-hair specific EST (expressed sequence tag) collection was mined for potential candidates. A total of nine polyketide synthase-like EST’s were identified representing five unique contigs, three of which were preferentially expressed in root hairs. The molecular and biochemical characterization of these three candidate polyketide synthases are presented, two of which represent a novel type of type III plant polyketide synthase.