Purification and characterization of the nuclease NucM of Erwinia chrysanthemi

The major periplasmic nuclease of Erwinia chrysanthemi strain 3937, NucM, has been purified near to homogeneity by a one step purification procedure, using chromatography on a sulfopropyl column. NucM cleaves randomly single and double-stranded DNA and RNA. It does not need divalent cations for its action, and is more active in low salt buffers. A serine and a histidine residue could be present in the catalytic site. Formation of disulfide bonds is necessary for NucM activity. NucM is probably synthesized as a reduced inactive polypeptide and becomes active in the periplasm once disulfide bonds are formed.