Heterogeneity of nucleoside kinases in marine microorganism cells

The incorporation of [3H]-thymidine and [3H]-uridine into nucleic acids of six marine microorganism strains belonging to different genera was studied. It was shown that the radioactive label of each of those exogenous precursors could be included into both the DNA and the RNA of bacterial cells. The activity of the nucleoside phosphorylation enzymes—thymidine and uridin kinases—was defined in bacterial cell extracts. The activity of thymidine kinase in the extracts is noticeably higher than the activity of uridine kinase, this enzyme, unlike uridine kinase, being present in all marine bacteria strains studied. After the partial purification of phosphorylation enzymes by means of ion-exchange chromatography, a number of enzymatic properties of nucleoside kinases and their substrate specificity were investigated. It was shown that the set of precursor phosphorylation enzymes in the strains under study differed in representatives of different marine bacterial genera.