Identification and preliminary characterization of external membrane-bound nuclease activities in Mycoplasma pulmonis.

Mycoplasma pulmonis has substantial DNase activity exposed on the cell surface. At least part of this activity is attributable to an endonuclease. The activity is destroyed at 56 degrees C and inhibited by either 5 mM EDTA or 10 mM zinc chloride. It can also be eliminated by treatment of intact organisms with trypsin and is regenerated by incubation of the treated organisms in a medium that supports protein synthesis. DNase exposed at the cell surface constitutes 20% of the total DNase activity present in M. pulmonis extracts.