title: Identification by Genome Mining of a Type I Polyketide Gene Cluster fromStreptomyces argillaceusInvolved in the Biosynthesis of Pyridine and Piperidine Alkaloids Argimycins P.
abstract: Genome mining of the mithramycin producerStreptomyces argillaceusATCC 12956 revealed 31 gene clusters for the biosynthesis of secondary metabolites, and allowed to predict the encoded products for 11 of these clusters. Cluster 18 (renamed clusterarp) corresponded to a type I polyketide gene cluster related to the previously described coelimycin P1 and streptazone gene clusters. Thearpcluster consists of fourteen genes, including genes coding for putative regulatory proteins (a SARP-like transcriptional activator and a TetR-like transcriptional repressor), genes coding for structural proteins (three PKSs, one aminotransferase, two dehydrogenases, two cyclases, one imine reductase, a type II thioesterase, and a flavin reductase), and one gene coding for a hypothetical protein. Identification of encoded compounds by this cluster was achieved by combining several strategies: (i) inactivation of the type I PKS genearpPIII; (ii) inactivation of the putative TetR-transcriptional repressorarpRII; (iii) cultivation of strains in different production media; and (iv) using engineered strains with higher intracellular concentration of malonyl-CoA. This has allowed identifying six new alkaloid compounds named argimycins P, which were purified and structurally characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. Some argimycins P showed a piperidine ring with a polyene side chain (argimycin PIX); others contain also a fused five-membered ring (argimycins PIV-PVI). Argimycins PI-PII showed a pyridine ring instead, and an additionalN-acetylcysteinyl moiety. These compounds seem to play a negative role in growth and colony differentiation inS. argillaceus, and some of them show weak antibiotic activity. A pathway for the biosynthesis of argimycins P is proposed, based on the analysis of proposed enzyme functions and on the structure of compounds encoded by thearpcluster.
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: Suhui
authors.initials: S
authors.lastname: Ye
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: Brian
authors.initials: B
authors.lastname: Molloy
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: Alfredo F
authors.initials: AF
authors.lastname: Braña
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Zabala
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Olano
authors.affiliation: EntreChem, S.L Oviedo, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Cortés
authors.affiliation: EntreChem, S.L Oviedo, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Morís
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Salas
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo Oviedo, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Méndez
keywords: Streptomyces; alkaloid; cryptic; growth; piperidine; pyridine; thioester reductase; type I polyketide synthase