Investigation of fungal iterative polyketide synthase functions using partially assembled intermediates.
Iterative polyketide synthases (PKSs) are large, multifunctional enzymes that resemble eukaryotic fatty acid synthases but can make highly functionalized secondary metabolites using complex and unresolved programming rules. During biosynthesis of the kinase inhibitor hypothemycin by  Hypomyces subiculosus , a highly reducing iterative PKS, Hpm8, cooperates with a nonreducing iterative PKS, Hpm3, to construct the advanced intermediate dehydrozearalenol (DHZ). The identity of putative intermediates in the formation of the highly reduced hexaketide portion of DHZ were confirmed by incorporation of (13)C-labeled N-acetylcysteamine (SNAC) thioesters using the purified enzymes. The results show that Hpm8 can accept SNAC thioesters of intermediates that are ready for transfer from its acyl carrier protein domain to its ketosynthase domain and assemble them into DHZ in cooperation with Hpm3. Addition of certain structurally modified analogues of intermediates to Hpm8 and Hpm3 can produce DHZ derivatives.
Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.
Zhizeng
Z
Gao
Jingjing
J
Wang
Amy K
AK
Norquay
Kangjian
K
Qiao
Yi
Y
Tang
John C
JC
Vederas
D000111:Acetylcysteine / Q000737:chemistry / Q000378:metabolism*; D055162:Biocatalysis; D006999:Hypocreales / Q000201:enzymology*; D018942:Macrolides / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D048630:Polyketide Synthases / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism*
D018942:Macrolides; D013438:Sulfhydryl Compounds; D048630:Polyketide Synthases; D000111:Acetylcysteine