High Sensitivity of the rpiAB Escherichia coli Mutants to Antibiotics Is Associated with the Participation of the deo-Operon in a Hypothetical Ribose-5-Phosphate Futile Cycle.

Previously, we demonstrated that disruption of ribose-5-phosphate biosynthesis in the pentose phosphate pathway increases the sensitivity of E. coli bacteria to a broad spectrum of antibiotics, and this sensitivity can be suppressed by deletion of the deoB gene. In this study, we showed that antibiotic sensitivity can also be suppressed by the deletion of the apt gene, which, along with the deoBD genes, constitutes the salvage pathway for purine base uptake. We propose that in the rpiAB mutant, these genes, together with the prs gene responsible for phosphoribosyl pyrophosphate (PRPP) synthesis, participate in a futile cycle, converting ATP to AMP and pyrophosphate (PPi). The data obtained on the genetic complementation of deletions of the apt and deoBD genes, combined with restored ATP levels in the rpiAB mutant cells, support the model of the hypothetical futile cycle of ribose-5-phosphate.