A Two-component Signal Transduction Pathway Regulates Manganese Homeostasis in Synechocystis 6803,

Elemental manganese is essential for the production of molecular oxygen by cyanobacteria, plants, and algae. In the cyanobacterium Synechocystis sp. PCC 6803, tran-scription of the mntCAB operon, encoding a high affin-ity Mn transporter, occurs under Mn starvation (nM Mn) conditions but not in Mn-sufficient (M Mn) growth me-dium. Using a strain in which the promoter of this operon directs the transcription of the luxAB reporter genes, we determined that inactivation of the slr0640 gene, which encodes a histidine kinase sensor protein component of a two-component signal transduction sys-tem, resulted in constitutive high levels of lux lumines-cence. Systematic targeted inactivation mutagenesis also identified slr1837 as the gene encoding the corre-sponding response regulator protein. We have name