Abstract
Phosphate is an essential nutrient in all organisms and is utilized for the synthesis of cellular components. We have previously identified histidine kinase Hik7 (sll0337) in Synechocystis sp. PCC 6803 as a sensor of phosphate-limiting conditions. In order to investigate the role of Hik7, we applied DNA microarray technique to analyze the gene expression of wild-type and Hik7-mutant cells in response to phosphate limitation. Incubation of wild-type cells in phosphate-limiting medium for 8 hours induced 28 genes that included alkaline phosphatase, phosphate transporters and genes encoding proteins of unknown functions. Inactivation of Hik7 completely eliminated the expression of all the phosphate limitation-inducible genes. These results suggest that Hik7 is only one sensor for phosphate limitation in this cyanobacterium.
