[Stability of a new product of oxidative stress in bacterial cells]

Data on 32P-label incorporation with subsequent addition of non-radiolabelled o-phosphate suggest that the new phosphorus compound, 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC), accumulated in the cells of some bacterial species in response to oxidative stress does not rapidly exchange phosphorus with external o-phosphate 3 hours after the introduction of its synthesis inducers into the Corynebacterium ammoniagenes culture. The accumulated MEC is retained in the cells despite the action of the cell wall synthesis inhibitor, chloramphenicol, or the energetic poisons, KCN and iodoacetate and also under anaerobic conditions. It has been shown that incubation of the cell-free lysate of a non-induced culture, Micrococcus luteus, with MEC does not result in MEC hydrolysis; therefore, MEC accumulation after the redox-mediator addition is hardly due to the hydrolase inactivation but, rather, is due to the activation of the MEC-synthesizing enzyme. The cells of C. ammoniagenes incorporate 32P from [32P]MEC but not 14C from [14C]MEC. This points to MEC hydrolysis prior to the uptake of its phosphoryl fragment by the cells. In this case 32P is found in the fractions differing by their position from MEC fractions. Experiments with sheep erythrocytes and mouse splenocytes revealed that MEC (10-100 micrograms per 1,000,000 splenocytes) does not influence the antibody production by these cells, whereas used at concentrations of 200-550 micrograms per 1,000,000 cells, MEC enhances the antibody production. However, while doing so, MEC causes the destruction of a considerable portion of splenocytes and sheep erythrocytes.