Pyrimidine Deoxyribonucleotide Metabolism in Members of the Class Mollicutes

Abstract

Cell extracts from six Acholeplasma species, six Mycoplasma species, and Spiroplasma floricola 23-6T (T = type strain) were examined for enzyme activities of pyrimidine deoxyribonucleotide metabolism. All of these organisms had thymidine kinase and thymidine phosphorylase activities, and all lacked deoxycytidine triphosphatase activity. The 13 members of the Mollicutes were separated into three groups by the presence or absence of the following four enzyme activities: (i) the adenosine triphosphate-insensitive deoxyuridine triphosphate-specific hydrolyzing deoxyuridine triphosphatase, (ii) a deoxyuridine monophosphate phosphatase, (iii) deoxycytidine deaminase, and (iv) deoxycytidine monophosphate deaminase. Five of the six Acholeplasma species (all Acholeplasma species except Acholeplasma florum L1T) had all four enzymatic activities. The six Mycoplasma species only had the deoxycytidine and deoxycytidine monophosphate deaminase activities. The only two plant isolates studied, A. florum L1T and S. floricola 23-6T, lacked all four enzymatic activities.