Mycoplasma contamination alters 2′‐deoxyadenosine metabolism in deoxycoformycin‐treated mouse leukemia cells

Abstract

Deoxycoformycin-treated P388 and L1210 mouse leukemia cells salvage 2'-deoxyadenosine from the medium only inefficiently, because deoxyadenosine deamination is blocked and its phosphorylation is limited by feedback controls. Mycoplasma contamination at a level that had no significant effect on the growth of the cells increased the salvage of deoxyadenosine greater than 10 fold over a 90 min period of incubation at 37 degrees C, but in this case deoxyadenosine was mainly incorporated into ribonucleotides and RNA via adenine formed from deoxyadenosine by mycoplasma adenosine phosphorylase. Deoxyadenosine was an efficient substrate for this enzyme, in contrast to 2',3'-dideoxyadenosine which was not phosphorolyzed. Mycoplasma infection was confirmed by the presence of uracil phosphoribosyltransferase activity and by culture isolation. The contaminant has been identified as Mycoplasma orale. Mycoplasma infection had no effect on the deamination and phosphorylation of deoxyadenosine and adenosine, on the salvage of hypoxanthine and adenine, or on the degradation of dAMP and dATP by the cells or on their acid and alkaline phosphatase activities.

Improvement of purine and pyrimidine antimetabolite-based anticancer treatment by selective suppression of mycoplasma-encoded catabolic enzymes

“…M orale infections of murine L1210 and P388 leukaemia cells were shown to change intracellular deoxyadenosine metabolism. 40 Ecto 5Ľ -nucleotidase activity was found in about 50% of M fermentans strains, effi ciently recognising adenosine monophosphate (AMP) as a substrate. 41 M fermentans was also noted to increase the activity of human ecto 5Ľ -nucleotidase activity in B cells and human monocytic leukaemia (THP-1) cells, and even in Daudi and Raji Burkitt's lymphoma cells that are normally 5Ľ -nucleotidase-negative.…”