Comparison of Enzymes of Nucleotide Metabolism in Two Members of the Mycoplasmataceae Family

The presence or absence of some enzymes of nucleotide metabolism has been suggested by other workers as being of possible value as criteria for some genera within the Mollicutes. We assayed subcellular fractions of Mycoplasma mycoides subsp. mycoides strain Y and Ureaplasma urealyticum 960T (T = type strain) for these activities. U. urealyticum 960T had characteristics similar to those noted previously (Williams and Pollack, Int. J. Syst. Bacteriol. 35:227-230, 1985) for some other species in the Mycoplasmataceae in that it (i) does not show a deoxyuridine triphosphate nucleotidohydrolase, (ii) does possess deoxycytidine deaminase, (iii) does not show a specific deoxyuridine monophosphate phosphatase, and (iv) does possess deoxycytidine monophosphate deaminase. M. mycoides differs from these other members of the Mycoplasmataceae in that it (i) does possess a deoxyuridine triphosphate nucleotidohydrolase and (ii) does not show deoxycytidine or cytidine deaminase activity, but it is similar in that it does not show a specific deoxyuridine monophosphate phosphatase and does possess deoxycytidine monophosphate deaminase. Extracts of U. urealyticum were fractionated and assayed for activities of a range of enzymes of nucleotide metabolism. Our results indicate a capacity for salvage pathways of nucleotide synthesis with similarities to those already proposed for M. mycoides and Acholeplasma laidlawii B-PG9.