title: Global transcriptional profiles of the copper responses in the cyanobacterium Synechocystis sp. PCC 6803.
abstract: Copper is an essential element involved in fundamental processes like respiration and photosynthesis. However, it becomes toxic at high concentration, which has forced organisms to control its cellular concentration. We have recently described a copper resistance system in the cyanobacterium Synechocystis sp. PCC 6803, which is mediated by the two-component system, CopRS, a RND metal transport system, CopBAC and a protein of unknown function, CopM. Here, we report the transcriptional responses to copper additions at non-toxic (0.3 µM) and toxic concentrations (3 µM) in the wild type and in the copper sensitive copR mutant strain. While 0.3 µM copper slightly stimulated metabolism and promoted the exchange between cytochrome c6 and plastocyanin as soluble electron carriers, the addition of 3 µM copper catalyzed the formation of ROS, led to a general stress response and induced expression of Fe-S cluster biogenesis genes. According to this, a double mutant strain copRsufR, which expresses constitutively the sufBCDS operon, tolerated higher copper concentration than the copR mutant strain, suggesting that Fe-S clusters are direct targets of copper toxicity in Synechocystis. In addition we have also demonstrated that InrS, a nickel binding transcriptional repressor that belong to the CsoR family of transcriptional factor, was involved in heavy metal homeostasis, including copper, in Synechocystis. Finally, global gene expression analysis of the copR mutant strain suggested that CopRS only controls the expression of copMRS and copBAC operons in response to copper.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Sevilla, Spain.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Giner-Lamia
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Sevilla, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: López-Maury
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Sevilla, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Florencio
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003300:Copper / Q000633:toxicity*; D045365:Cytochromes c6 / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D058977:Molecular Sequence Annotation; D009154:Mutation; D009876:Operon; D010970:Plastocyanin / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D046939:Synechocystis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D001426:Bacterial Proteins; D045365:Cytochromes c6; D004268:DNA-Binding Proteins; D004785:Environmental Pollutants; D026901:Membrane Transport Proteins; D017382:Reactive Oxygen Species; D003300:Copper; D010970:Plastocyanin