MYCOPLASMA CONTAMINATION ALTERS 2'-DEOXYADENOSINE METABOLISM IN DEOXYCOFORMYCIN-TREATED MOUSE LEUKEMIA-CELLS

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 >10 fold over a 90 min period of incubation at 37°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. Copyright © 1990 Wiley‐Liss, Inc.