STABILITY OF A RECENTLY DISCOVERED PRODUCT OF OXIDATIVE STRESS IN BACTERIAL-CELLS

The recently discovered phosphorus compound 2-C-methyl-D-erythritol-2, 4-cyclopyrophosphate (MEC) accumulates in cells of some bacterial spec ies in response to oxidative stress, e.g., in Corynebacterium ammoniag enes cells after the addition of an inducer into the culture medium; d ata on P-32-label incorporation into MEC with subsequent addition (aft er 3 h) of non-radiolabelled orthophosphate indicates that external or thophosphate does not rapidly exchange with the label. The retention o f accumulated MEC in cells is insensitive to the addition of a cell wa ll synthesis inhibitor (penicillin), a protein synthesis inhibitor (ch loramphenicol), energetic poisons (KCN and iodoacetate), and also to a naerobic conditions Incubation of MEC with a cell-free lysate of a non -induced culture of Micrococcus luteus did not hydrolyze MEG; therefor e, MEC accumulation after addition of a redox mediator is not due to i nactivation of a hydrolase but rather is due to activation of the MEC- synthesizing enzyme: The C. ammoniagenes cells incorporate P-32 from [ P-32]MEC, but not C-14 from [C-14]MEC. This suggests that MEC is hydro lyzed before phosphoryl radical is taken up by the cells, and in this case P-32 is found on fractions not caontaining MEC. Antibody producti on by mouse splenocytes against sheep erythrocytes was not influenced by 10-100 mu g MEC per 10(6) splenocytes. At 200-550 mu g MEC per 10(6 ) splenocytes antibody production was enhanced, but at the same time s ignificant fractions of the splenocytes and erythrocytes were destroye d.