Protein phosphatase able to dephosphorylate StkP-P and a phosphothreonine residue in a phosphopeptide synthetic substrate. PhpP and its cognate protein kinase StkP appear to constitute a functional signaling couple in vivo, PhpP's primary role probably being to control phosphorylation levels of StkP and of its targets (which include LocZ, DivIVA and KhpB (also called EloR/Jag)). PhpP thus performs an essential control of StkP activity. Overexpression confers an stkP deletion-like phenotype. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 manganese ions per subunit. Other divalent cations, such as Mg(2+) or Ca(2+), cannot serve as cofactors. Phosphatase activity is inhibited by NaF but not by okadaic acid. Interacts with the kinase domain of StkP. Mainly localizes to the midcell division sites. PhpP and StkP interact within a membrane-associated protein complex facing the cytoplasm. The phpP and stkP genes form an operon. Attempts to construct an in-frame deletion of the phpP gene were unsuccessful and an allele encoding inactive D231A PhpP phosphatase is lethal in a wild-type genetic background. This suggests that PhpP is essential (PubMed:19502404). Another group has generated a phpP deletion using a two-step negative selection strategy, which has a hyper-phosphorylated phenotype. Cells grow more slowly, are smaller and form short chains, reach a lower final density, are more sensitive to oxidative stress, growth is impaired at 40 degrees Celsius, competence is decreased and mild defects are seen in cell division. Unlike the stkP deletion, cells are unaffected by high salt, acidic and basic pH (PubMed:27776484). Strain Rx1 is unencapsulated. Belongs to the PP2C family.