The antibiotic L-155,175, a potent antiparasitic and antifungal compound, has an unusual structure involving 16-membered macrolides that contain a tetrahydropyran ring connected through a three-carbon linker chain. To identify the biosynthetic gene cluster for L-155,175, a genomic DNA library of Streptomyces hygroscopicus ATCC31955 was constructed and screened with a degenerate primer set designed from a conserved region of the ketosynthase (KS) domain. Sequence analysis of a fosmid clone, pEY1D8 (34 kb), revealed multiple open reading frames (ORFs) encoding type I polyketide synthase (PKS). To determine whether the cloned genes are involved in L-155,175 biosynthesis, a deletion mutant (1D8m) was generated by homologous recombination, in which the gene encoding the KS domain was substituted with an apramycin-resistance gene by PCR-targeted Streptomyces gene replacement. LC-MS analysis showed that L-155,175 production was completely abolished in the 1D8m strain, thereby proving that the cloned gene is responsible for L-155,175 biosynthesis. The sequencing of two other fosmid clones (pEY8B10 and pEY1C9) harboring overlapping sequences from pEY1D8 revealed a 60-kb DNA segment encoding six ORFs for type I PKS harboring 12 modules. The domain organization of the PKS modules encoded by PKS exactly matched the structure of L-155,175. This is the first report on the gene cluster involved in the biosynthesis of L-155,175.
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Mar Environ Res
January 2025
University of Technology Sydney, The School of Life Sciences, Ultimo, NSW, 2007, Australia. Electronic address:
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Institute of Agricultural Engineering, Anhui Academy of Agricultural Sciences, Hefei, Anhui, China.
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School of Landscape Architecture, Zhejiang Agriculture and Forestry University, Hangzhou, 311300, Zhejiang, China.
Gene duplications provide evolutionary potentials for generating novel functions. Chimonanthus praecox and C. salicifolius are closely related species from Calycantaceae, Magnoliids.
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Computational Evolutionary Genomics Lab, Department of Biological Sciences, IISER Bhopal, Bhauri, Madhya Pradesh, India.
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Department of Zoology, The University of Burdwan, Bardhaman, West Bengal, 713104, India.
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