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.
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http://dx.doi.org/10.1016/j.chembiol.2013.07.016 | DOI Listing |
Curr Microbiol
December 2024
Faculty of Science, Molecular Biology and Genetics Department, Gebze Technical University, Gebze, 41400, Kocaeli, Türkiye.
The genus Streptomyces is a group of gram-positive bacteria that exhibit a distinctive growth pattern characterised by elongated, branched hyphae. Streptomyces coelicolor A3(2), which produces at least five different antibiotics, is a model organism that is widely used in genetic studies. There are very few studies in Streptomyces on the ATP-dependent Lon protease, which has very important functions in every organism and is particularly responsible for protein homeostasis.
View Article and Find Full Text PDFSci Rep
October 2024
Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, 252-0880, Japan.
The LitR/CarH family comprises adenosyl B-based photosensory transcriptional regulators that control light-inducible carotenoid production in nonphototrophic bacteria. In this study, we established a blue-green light-inducible hyperexpression system using LitR and its partner ECF-type sigma factor LitS in streptomycin-producing Streptomyces griseus NBRC 13350. The constructed multiple-copy number plasmid, pLit19, carried five genetic elements: pIJ101rep, the thiostrepton resistance gene, litR, litS, and σ-recognized light-inducible crtE promoter.
View Article and Find Full Text PDFMicrob Cell Fact
August 2024
Departamento de Microbiología y Genética, Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca (USAL), C/ Zacarías González, nº 2, Salamanca, 37007, Spain.
Background: Several two-component systems of Streptomyces coelicolor, a model organism used for studying antibiotic production in Streptomyces, affect the expression of the bfr (SCO2113) gene that encodes a bacterioferritin, a protein involved in iron storage. In this work, we have studied the effect of the deletion mutant ∆bfr in S. coelicolor.
View Article and Find Full Text PDFPLoS One
August 2024
Department of Life Technologies, University of Turku, Turku, Finland.
The biosynthetic pathway of actinorhodin in Streptomyces coelicolor A3(2) has been studied for decades as a model system of type II polyketide biosynthesis. The actinorhodin biosynthetic gene cluster includes a gene, actVI-orfA, that encodes a protein that belongs to the nuclear transport factor-2-like (NTF-2-like) superfamily. The function of this ActVI-ORFA protein has been a long-standing question in this field.
View Article and Find Full Text PDFBMC Microbiol
October 2023
Department of Bioscience, Faculty of Life Sciences, Tokyo University of Agriculture, Sakuragaoka, Tokyo, Setagaya-Ku, 156-8502, Japan.
Background: Previous studies have revealed a nitric oxide (NO) metabolic cycle in which NO, nitrate (NO), and nitrite (NO) circulate. The NO produced in this cycle serves as a signalling molecule that regulates actinorhodin (ACT) production via the DevS/DevR NO-dependent two-component system (TCS) in Streptomyces coelicolor A3(2) M145. However, the mechanisms involved in the regulation of NO signalling in S.
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