The cyanobacterium Synechococcus sp. strain PCC 7942 contains a second alkaline phosphatase encoded by phoV

The cyanobacterium Synechococcus sp. strain PCC 7942 contains two alkaline phosphatases (APases) that are encoded by the phoV gene. These are the phosphate-repressible 145 kDa PhoA and the phosphate-irrepressible 61.3 kDa PhoV. The presence of a second APase is probably necessary to maintain the phosphate level in the cells under conditions of stress. Characterization of the gene product reveals that PhoV has a broad pH optimum, requires Zn2+ for activity and has a wide substrate specificity. Mn2+ and phosphate inhibit the protein.