Pentose Phosphate Pathway Protects E. coli from Antibiotic Lethality

Abstract

Disruption of both branches of the canonical pentose phosphate pathway (PPP) in E. coli by combined inactivation of the zwf and talAB genes provokes the restoration of the ancient anabolic variant of PPP (aPPP). In the aPPP, pentose-5-phosphates are synthesized unidirectionally from fructose-6-phosphate and glyceraldehyde-3-phosphate by transketolase B, aldolase A, and phosphatase GlpX, converting sedoheptulose-1,7-bisphosphate to sedoheptulose-7-phosphate. Unexpectedly, the double zwf talAB mutant exhibits decreased survival after treatment by diverse classes of antibiotics with little effect on the minimal inhibitory concentration. Simultaneously, we found that killing effect of antimicrobials on the zwf talAB mutant could be reversed by the inactivation of either purR or deoB genes, both responsible for ribose-5-phosphate content in the mutant strain. Enhanced biosynthesis of the cell wall component ADP-heptose from sedoheptulose-7-phosphate also suppressed killing effect of antibiotics on the zwf talAB mutant. Furthermore, the inactivation of the Entner-Doudoroff pathway ({Delta}edd) or shifting the metabolic equilibrium by the addition of exogenous phosphogluconate reverts aPPP to glycolysis, preventing the accumulation of excess pentose phosphates and the occurrence of the futile cycle in zwf talAB cells, thus desensitizing them to antibiotics. Our findings show that ribose-5-phosphate metabolism plays a crucial role in bacterial tolerance to a wide range of bactericidal antibiotics. We propose that targeting PPP could be a promising strategy for developing new therapeutic agents aimed at potentiating clinically significant antimicrobials. IMPORTANCERecent studies have revealed the crucial role of bacterial cells metabolic status in its susceptibility to the lethal action of antibacterial drugs. However, there is still no clear understanding of which key metabolic nodes are optimal targets to improve the effectiveness of bacterial infection treatment. Our study establishes that the disruption of the canonical pentose phosphate pathway induces one-way anabolic synthesis of pentose phosphates (aPPP) in E. coli cells, significantly increasing the killing efficiency of various antibiotics. It is also demonstrated that the activation of ribose-5-phosphate utilization processes restores bacterial tolerance to antibiotics. We consider the synthesis of ribose-5-phosphate to be one of the determining factors of bacterial cell stress resistance. Understanding bacterial metabolic pathways, particularly the aPPPs role in antibiotic sensitivity, offers insights for developing novel adjuvant therapeutic strategies to enhance antibiotic potency.