title: The Myxococcus xanthus two-component system CorSR regulates expression of a gene cluster involved in maintaining copper tolerance during growth and development.
abstract: Myxococcus xanthus is a soil-dwelling member of the δ-Proteobacteria that exhibits a complex developmental cycle upon starvation. Development comprises aggregation and differentiation into environmentally resistant myxospores in an environment that includes fluctuations in metal ion concentrations. While copper is essential for M. xanthus cells because several housekeeping enzymes use it as a cofactor, high copper concentrations are toxic. These opposing effects force cells to maintain a tight copper homeostasis. A plethora of paralogous genes involved in copper detoxification, all of which are differentially regulated, have been reported in M. xanthus. The use of in-frame deletion mutants and fusions with the reporter gene lacZ has allowed the identification of a two-component system, CorSR, that modulates the expression of an operon termed curA consisting of nine genes whose expression slowly increases after metal addition, reaching a plateau. Transcriptional regulation of this operon is complex because transcription can be initiated at different promoters and by different types of regulators. These genes confer copper tolerance during growth and development. Copper induces carotenoid production in a ΔcorSR mutant at lower concentrations than with the wild-type strain due to lack of expression of a gene product resembling subunit III of cbb3-type cytochrome c oxidase. This data may explain why copper induces carotenoid biosynthesis at suboptimal rather than optimal growth conditions in wild-type strains.
authors.affiliation: Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
authors.forename: María Celestina
authors.initials: MC
authors.lastname: Sánchez-Sutil
authors.forename: Juana
authors.initials: J
authors.lastname: Pérez
authors.forename: Nuria
authors.initials: N
authors.lastname: Gómez-Santos
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Shimkets
authors.forename: Aurelio
authors.initials: A
authors.lastname: Moraleda-Muñoz
authors.forename: José
authors.initials: J
authors.lastname: Muñoz-Dorado
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D003300:Copper / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000187:drug effects / Q000502:physiology; D008658:Inactivation, Metabolic / Q000235:genetics*; D005810:Multigene Family / Q000187:drug effects / Q000502:physiology; D016941:Myxococcus xanthus / Q000235:genetics* / Q000254:growth & development*; D009876:Operon / Q000187:drug effects; D010641:Phenotype
chemical_list: D001426:Bacterial Proteins; D003300:Copper