title: Collismycin A biosynthesis in Streptomyces sp. CS40 is regulated by iron levels through two pathway-specific regulators.
abstract: Two putative pathway-specific regulators have been identified in the collismycin A gene cluster: ClmR1, belonging to the TetR-family, and the LuxR-family transcriptional regulator ClmR2. Inactivation of clmR1 led to a moderate increase of collismycin A yields along with an early onset of its production, suggesting an inhibitory role for the product of this gene. Inactivation of clmR2 abolished collismycin A biosynthesis, whereas overexpression of ClmR2 led to a fourfold increase in production yields, indicating that ClmR2 is an activator of collismycin A biosynthesis. Expression analyses of the collismycin gene cluster in the wild-type strain and in ΔclmR1 and ΔclmR2 mutants confirmed the role proposed for both regulatory genes, revealing that ClmR2 positively controls the expression of most of the genes in the cluster and ClmR1 negatively regulates both its own expression and that of clmR2. Additionally, production assays and further transcription analyses confirmed the existence of a higher regulatory level modulating collismycin A biosynthesis in response to iron concentrations in the culture medium. Thus, high iron levels inhibit collismycin A biosynthesis through the repression of clmR2 transcription. These results have allowed us to propose a regulatory model that integrates the effect of iron as the main environmental stimulus controlling collismycin A biosynthesis.
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Natalia M
authors.initials: NM
authors.lastname: Vior
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Olano
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: García
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Méndez
authors.affiliation: Departamento de Biología Funcional e Instituto Universitario de Oncología del Principado de Asturias (I.U.O.P.A), Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Salas
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000378:metabolism; D000595:Amino Acid Sequence; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D007501:Iron / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D008969:Molecular Sequence Data; D005810:Multigene Family; D016415:Sequence Alignment; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D014157:Transcription Factors; C089907:collismycin A; D015082:2,2'-Dipyridyl; D007501:Iron