The Determinants of Activity and Specificity in Actinorhodin Type II Polyketide Ketoreductase

Pouya Javidpour, Joel Bruegger, Supawadee Srithahan, Tyler P Korman, Matthew P Crump, John Crosby, Michael D Burkart, Shiou-Chuan Tsai

Research output: Contribution to journalArticle (Academic Journal)peer-review

22 Citations (Scopus)
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In the actinorhodin type II polyketide synthase, the first polyketide modification is a regiospecific C9-carbonyl reduction, catalyzed by the ketoreductase (actKR). Our previous studies identified the actKR 94-PGG-96 motif as a determinant of stereospecificity. The molecular basis for reduction regiospecificity is, however, not well understood. In this study, we examined the activities of 20 actKR mutants through a combination of kinetic studies, PKS reconstitution, and structural analyses. Residues have been identified that are necessary for substrate interaction, and these observations have suggested a structural model for this reaction. Polyketides dock at the KR surface and are steered into the enzyme pocket where C7-C12 cyclization is mediated by the KR before C9-ketoreduction can occur. These molecular features can potentially serve as engineering targets for the biosynthesis of novel, reduced polyketides.
Original languageEnglish
Pages (from-to)1225-1234
Number of pages10
JournalChemistry & Biology
Issue number10
Publication statusPublished - 12 Sep 2013

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