Purine and Pyrimidine Metabolism in Mollicutes Species

Abstract

We studied the purine enzyme activities in dialyzed cytoplasmic extracts from the following eight species, representing four genera, of Mollicutes: Mycoplasma pneumoniae FHT (T = type strain) and M129, Mycoplasma bovigenitalium PG-11T, Mycoplasma hominis PG-21T and 1620, Mycoplasma genitalium G-37T, Mycoplasma hyopneuominae JT, Ureaplasma urealyticum T960t, Spiroplasma citri Maroc-R8A2t, and Anaeroplasma intermedium 5LA. In an investigation of purine nucleoside kinase activity we also included M. hominis 13408, 10144, 13428, 1612, 1184, and Botte. All of these Mollicutes species except U. urealyticum had purine phosphoribosyltransferase activity for adenine, hypoxanthine, and guanine; U. urealyticum had only adenine phosphoribosyltransferase activity. All of the organisms had nucleoside phosphorylate activity which used either ribose 1-phosphate or deoxyribose 1-phosphate and adenine, hypoxanthine, or guanine for the synthesis of nucleosides and adenosine, deoxyadenosine, guanosine, deoxyguanosine, inosine, or deoxyinosine in the reverse direction. All had 5''-nucleotidase activtiy for adenosine monophosphate, deoxyadenosine monophosphate, inosine monophosphate, or guanosine monophosphate. Only M. hominis 1620, 13408, 10144, and 13428, A. intermedium, and S. citri had pyrophosphate-dependent nucleoside kinase activity. Only S. criti had nucleoside kinase activity with adenosine triphosphate and deoxyguanosine. We studied pyrimidine enzyme activities in all of the Mollicutes species except M. hominis and M. bovigenitalium. All of the Mollicutes species assayed had thymidine, thymidylate, and deoxycytidine kinase and thymidine and uridine phosphorylase activities. All of the Mycoplasma spp. had deoxycytotidine monophosphate and cytidine-dexycytidine deaminase activities. All of the Mycoplasma spp. and U. urealyticum lacked deoxyuridine triphosphatase activity. U. urealyticum lacked deoxycytidine monophosphate activity, but otherwise it resembled all of the Mycoplasma spp. A. intermedium and S. citri differed from each other and from Mycoplasma spp. and U. urealyticum in the patterns of pyrimidine enzyme activities . Pyrophosphate-dependent nucleoside kinase activity was the most variably detected activity. None of the Mycoplasma spp. except four of eight strains of M. hominis had this kinase activity. Likewise, U. urealyticum did not have the pyrophosphate-dependent nucleoside kinase activity; however, A. intermedium and S. citri did have this enzyme activity. The absence of deoxyuridine triphophatase activity in all Mycoplasma spp. may be related to their proposed rapid evolution and the relative lack of conserved sequences in their 5S ribosomal ribonucleic acids.