Inhibition Kinetics and Emodin Cocrystal Structure of a Type II Polyketide Ketoreductase,
- 19 January 2008
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 47 (7), 1837-1847
- https://doi.org/10.1021/bi7016427
Abstract
Type II polyketides are a class of natural products that include pharmaceutically important aromatic compounds such as the antibiotic tetracycline and antitumor compound doxorubicin. The type II polyketide synthase (PKS) is a complex consisting of 5−10 standalone domains homologous to fatty acid synthase (FAS). Polyketide ketoreductase (KR) provides regio- and stereochemical diversity during the reduction. How the type II polyketide KR specifically reduces only the C9 carbonyl group is not well understood. The cocrystal structures of actinorhodin polyketide ketoreductase (actKR) bound with NADPH or NADP+ and the inhibitor emodin were solved with the wild type and P94L mutant of actKR, revealing the first observation of a bent p-quinone in an enzyme active site. Molecular dynamics simulation help explain the origin of the bent geometry. Extensive screening for in vitro substrates shows that unlike FAS KR, the actKR prefers bicyclic substrates. Inhibition kinetics indicate that actKR follows an ordered Bi Bi mechanism. Together with docking simulations that identified a potential phosphopantetheine binding groove, the structural and functional studies reveal that the C9 specificity is a result of active site geometry and substrate ring constraints. The results lay the foundation for the design of novel aromatic polyketide natural products with different reduction patterns.Keywords
This publication has 44 references indexed in Scilit:
- Structural and Functional Studies on SCO1815: A β-Ketoacyl-Acyl Carrier Protein Reductase from Streptomyces coelicolor A3(2)Biochemistry, 2006
- Heterologous Biosynthesis of Truncated Hexaketides Derived from the Actinorhodin Polyketide SynthaseJournal of Natural Products, 2004
- Context-Dependent Behavior of the Enterocin Iterative Polyketide Synthase: A New Model for KetoreductionCell Chemical Biology, 2004
- Cofactor-Induced Conformational Rearrangements Establish a Catalytically Competent Active Site and a Proton Relay Conduit in FabGStructure, 2004
- Molecular basis of Celmer’s rules: role of the ketosynthase domain in epimerisation and demonstration that ketoreductase domains can have altered product specificity with unnatural substratesCell Chemical Biology, 2001
- SWISS‐MODEL and the Swiss‐Pdb Viewer: An environment for comparative protein modelingElectrophoresis, 1997
- Engineered biosynthesis of novel polyketides: evidence for temporal, but not regiospecific, control of cyclization of an aromatic polyketide precursorCell Chemical Biology, 1994
- Isotope, pulse-chase, stopped-flow, and rapid quench studies on the kinetic mechanism of bovine dihydropteridine reductaseBiochemistry, 1984
- Molecular cloning of the whole biosynthetic pathway of a Streptomyces antibiotic and its expression in a heterologous hostNature, 1984
- Fatty Acid Synthetase from Pig LiverJBIC Journal of Biological Inorganic Chemistry, 1971