title: A gene cluster involved in metal homeostasis in the cyanobacterium Synechocystis sp. strain PCC 6803.
abstract: A gene cluster composed of nine open reading frames (ORFs) involved in Ni(2+), Co(2+), and Zn(2+) sensing and tolerance in the cyanobacterium Synechocystis sp. strain PCC 6803 has been identified. The cluster includes an Ni(2+) response operon and a Co(2+) response system, as well as a Zn(2+) response system previously described. Expression of the Ni(2+) response operon (nrs) was induced in the presence of Ni(2+) and Co(2+). Reduced Ni(2+) tolerance was observed following disruption of two ORFs of the operon (nrsA and nrsD). We also show that the nrsD gene encodes a putative Ni(2+) permease whose carboxy-terminal region is a metal binding domain. The Co(2+) response system is composed of two divergently transcribed genes, corR and corT, mutants of which showed decreased Co(2+) tolerance. Additionally, corR mutants showed an absence of Co(2+)-dependent induction of corT, indicating that CorR is a transcriptional activator of corT. To our knowledge, CorR is the first Co(2+)-sensing transcription factor described. Our data suggest that this region of the Synechocystis sp. strain PCC 6803 genome is involved in sensing and homeostasis of Ni(2+), Co(2+), and Zn(2+).
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, E-41092 Sevilla, Spain.
authors.forename: M
authors.initials: M
authors.lastname: García-Domínguez
authors.forename: L
authors.initials: L
authors.lastname: Lopez-Maury
authors.forename: F J
authors.initials: FJ
authors.lastname: Florencio
authors.forename: J C
authors.initials: JC
authors.lastname: Reyes
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D003035:Cobalt / Q000378:metabolism / Q000494:pharmacology; D000458:Cyanobacteria / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006706:Homeostasis; D019216:Metals, Heavy / Q000378:metabolism* / Q000494:pharmacology*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009532:Nickel / Q000378:metabolism / Q000494:pharmacology; D016366:Open Reading Frames / Q000235:genetics; D014158:Transcription, Genetic; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C051124:MerR protein, Bacteria; D019216:Metals, Heavy; D003035:Cobalt; D009532:Nickel; D015032:Zinc