Open AccessA Gene Cluster Involved in Metal Homeostasis in the Cyanobacterium Synechocystis sp. Strain PCC 6803
Author(s) -
Mario García-Domínguez,
Luis LópezMaury,
Francisco J. Florencio,
José Carlos Castañeda Reyes
Publication year - 2000
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.182.6.1507-1514.2000
Subject(s) - operon , biology , synechocystis , orfs , mutant , gene cluster , gene , open reading frame , permease , strain (injury) , transcription (linguistics) , l arabinose operon , genetics , biochemistry , peptide sequence , linguistics , philosophy , anatomy
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+).