Cytoplasmic fractions from species of the genera , and were assayed for NADH oxidase (NADH ox), ATP- and PP-dependent phosphofructokinase (PFK), ATP- and PP-dependent deoxyguanosine kinase (dGUOK), thymidine kinase (TK), TMP kinase (TMPK), glucose-6-phosphate dehydrogenase (G6Pde), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), phosphoenolpyruvate carboxylase, hypoxanthine-guanine phosphoribosyl transferase, dUTPase, and uracil-DNA glycosylase (UNG) activities. Membrane fractions were also examined for NADH ox activity. These activities were used as indicators of the presence and relative activities of major metabolic and DNA repair pathways. This was the first study to determine the presence of these enzymes in members of the genera and . Using the data obtained, we constructed a preliminary scheme for distinguishing genera of the class on the basis of the results of signature functional enzyme assays. This scheme includes phylogenetic relationships deduced from rRNA analyses, but is more informative with respect to metabolic potential. The criteria used include the presence of PP-dependent PFK, urease, dUTPase, and dGUOK activities. ELCN-1 (T = type strain), M-1, F7, TAC, L1, PG18, and PN525 were similar in most respects. NADH ox activity was localized in the cytoplasm of these organisms. These strains had ATP-dependent PFK, MDH, LDH, ATP- and PP-dependent dGUOK, and UNG activities, but not dUTPase or G6Pde activities. In contrast, C112, 19L, C1, PG49, and 72-043 had membrane-localized NADH ox activity, PP-dependent PFK, G6Pde, and dUTPase activities, and significantly lower MDH and LDH activities and exhibited a faster rate with PP than with ATP in the dGUOK reaction. All of the members of the tested had hypoxanthine-guanine phosphoribosyl transferase, phosphoenolpyruvate carboxylase, and (except for TACf) UNG activities. All of the strains except PN525 had TK, TMPK, and UNG activities. TAC was distinguished by having no detectable dUTPase, UNG, TK, and TMPK activities, indicating that there is a severe restriction in or an absence of a synthetic route to dTTP. Our data also suggest that PN525 is a member of an unrecognized metabolic subgroup of the genus or is not an strain.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error