Thioesterases and the premature termination of polyketide chain elongation in rifamycin B biosynthesis by Amycolatopsis mediterranei S699

• Published in: Journal of antibiotics Vol. 53; no. 5; p. 484
• Main Authors: Doi-Katayama, Y, Yoon, Y J, Choi, C Y, Yu, T W, Floss, H G, Hutchinson, C R
• Format: Journal Article
• Language: English
• Published: Japan 2000
• Subjects: Actinomycetales - genetics; Actinomycetales - metabolism; Amino Acid Sequence; Anti-Bacterial Agents - biosynthesis; Base Sequence; Esterases - metabolism; Genes, Bacterial; Molecular Sequence Data; Multienzyme Complexes - genetics; Mutation; Peptide Chain Elongation, Translational; Rifamycins - biosynthesis
• ISSN: 0021-8820
• DOI: 10.7164/antibiotics.53.484

The role of two thioesterase genes in the premature release of polyketide synthase intermediates during rifamycin biosynthesis in the Amycolatopsis mediterranei S699 strain was investigated. Creation of an in-frame deletion in the rifR gene led to a 30 approximately 60% decrease in the production of both rifamycin B by the S699 strain or a series of tetra- to decaketide shunt products of polyketide chain assembly by the rifF strain. Since a similar percentage decrease was seen in both genetic backgrounds, we conclude that the RifR thioesterase 2 is not involved in premature release of the carbon chain assembly intermediates. Similarly, fusion of the Saccharopolyspora erythraea DEBS3 thioesterase I domain to the C-terminus of the RifE PKS subunit did not result in a noticeable increase in the amount of the undecaketide intermediate formed nor in the amounts of the tetra- to decaketide shunt products. Hence, premature release of the carbon chain assembly intermediates is an unusual property of the Rif PKS itself.