Heme-based oxygen sensor protein displaying phosphodiesterase (PDE) activity toward c-di-GMP in response to oxygen availability. Involved in the modulation of intracellular c-di-GMP levels, in association with DosC which catalyzes the biosynthesis of c-di-GMP (diguanylate cyclase activity). Cyclic-di-GMP is a second messenger which controls cell surface-associated traits in bacteria. Has very poor PDE activity on cAMP  but is not active with cGMP, bis(p-nitrophenyl) phosphate or p-nitrophenyl phosphate. Via its PDE activity on c-di-GMP, DosP regulates biofilm formation through the repression of transcription of the csgBAC operon, which encodes curli structural subunits