One of the most striking features of complex polyketides is the presence of numerous methyl- and hydroxyl-bearing stereogenic centers. To investigate the biochemical basis for the control of polyketide stereochemistry and to establish the timing and mechanism of the epimerization at methyl-bearing centers, a series of incubations was carried out using reconstituted components from a variety of modular polyketide synthases. In all cases the stereochemistry of the product was directly correlated with the intrinsic stereospecificity of the ketoreductase domain, independent of the particular chain elongation domains that were used, thereby establishing that methyl group epimerization, when it does occur, takes place after ketosynthase-catalyzed chain elongation. The finding that there were only minor differences in the rates of product formation observed for parallel incubations using an epimerizing ketoreductase domain and the nonepimerizing ketoreductase domain supports the proposal that the epimerization is catalyzed by the ketoreductase domain itself.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699857 | PMC |
| http://dx.doi.org/10.1021/ja908296m | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The Relationship between Substrate Structure and Selectivity of Ketoreduction in Multimodular Polyketide Synthases: A Comparative Study of A-Type Ketoreductases from Late Modules Using Complex Precursor Analogues.
ACS Chem Biol
January 2025
Professur Organische Chemie IV, Fakultät für Biologie, Chemie und Geowissenschaften, Department of Chemistry, Universität Bayreuth, 95447 Bayreuth, Germany.
Ketoreductases (KRs) are domains in the reductive loops of type I polyketide synthases (PKSs) and are responsible for the majority of stereocenters in reduced polyketides. Although the highly stereoselective reduction of ACP-bound β-ketothioester intermediates by KRs is crucial for the overall functioning of PKSs, the substrate-dependent stereoselectivity of KRs is a factor that is not yet fully understood, especially for KR domains in late PKS modules that act on biosynthetic precursors with complex polyketidic moieties. We present studies on the three KR domains FosKR7, PlmKR6, and EryKR6 from the biosynthetic pathways of fostriecin, phoslactomycin, and erythromycin by in vitro assays using close surrogates of the octaketidic FosKR7 biosynthetic precursor, complex derivatives and a diketide in the form of their biomimetic -acetylcysteamine thioesters.
View Article and Find Full Text PDFStructure-based reshaping of a new ketoreductase from Sphingobacterium siyangense SY1 toward α-haloacetophenones.
Int J Biol Macromol
October 2024
School of Life Sciences and Biopharmaceutical Sciences, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe, Shenyang 110016, People's Republic of China. Electronic address:
Ketoreductases play an indispensable role in the asymmetric synthesis of chiral drug intermediates, and an in-depth understanding of their substrate selectivity can improve the efficiency of enzyme engineering. In this endeavor, a new short-chain dehydrogenase/reductase (SDR) SsSDR1 identified from Sphingobacterium siyangense SY1 by gene mining method was successfully cloned and functionally expressed in Escherichia coli. Its activity against halogenated acetophenones has been tested and the results illustrated that SsSDR1-WT exhibits high activity for 3,5-bis(trifluoromethyl)acetophenone (1f), an important precursor in the synthesis of aprepitant.
View Article and Find Full Text PDFBioinformatic prediction of the stereoselectivity of modular polyketide synthase: an update of the sequence motifs in ketoreductase domain.
Beilstein J Org Chem
July 2024
Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Hangzhou 310030, China.
Polyketides are a major class of natural products, including bioactive medicines such as erythromycin and rapamycin. They are often rich in stereocenters biosynthesized by the ketoreductase (KR) domain within the polyketide synthase (PKS) assembly line. Previous studies have identified conserved motifs in KR sequences that enable the bioinformatic prediction of product stereochemistry.
View Article and Find Full Text PDFTheoretical Analysis of Selectivity Differences in Ketoreductases toward Aldehyde and Ketone Carbonyl Groups.
J Chem Inf Model
April 2024
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, P. R. China.
alcohol dehydrogenase (ADH) and ketoreductase from . CA49 (KRED12) exhibit different chemoselectivity and stereoselectivity toward a substrate with both keto and aldehyde carbonyl groups. ADH selectively reduces the keto carbonyl group while retaining the aldehyde carbonyl group, producing optically pure -alcohols.
View Article and Find Full Text PDFBiosynthesis of -AT PKS-Derived Shuangdaolides Featuring a -acting Enzyme for Online Epoxidation.
ACS Chem Biol
December 2023
Helmholtz International Lab for Anti-infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong 266237, China.
Bacterial -acyltransferase polyketide synthases (-AT PKSs) synthesize natural products with intricate structures and potent biological activities. They generally contain various unusual modules or -acting enzymes. Herein, we report the -AT PKS-derived biosynthetic pathway of the shuangdaolide with a rare internal 2-hydroxycyclopentenone moiety.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!