Bacillus subtilis produces (p)ppGpp in response to the bacteriostatic antibiotic chloramphenicol to prevent its potential bactericidal effect. Issue 2 (30th June 2022)

• Record Type: Journal Article
• Authors: Yang, Jin; Barra, Jessica T.; Fung, Danny K.; Wang, Jue D.
• Is Part Of: MLife. Volume 1:Issue 2(2022)
• Page Start: 101
• Page End: 113
• Publication Date: 2022-06-30
• Subjects: antibiotic tolerance -- bactericidal antibiotic -- bacteriostatic antibiotic -- GTP -- (p)ppGpp; Microbiology -- Periodicals; Microbiology; Periodicals; 579; 579
• DOI: 10.1002/mlf2.12031
• Languages: English
• ISSNs: 2770-100X

Abstract

Abstract: Antibiotics combat bacteria through their bacteriostatic (by growth inhibition) or bactericidal (by killing bacteria) action. Mechanistically, it has been proposed that bactericidal antibiotics trigger cellular damage, while bacteriostatic antibiotics suppress cellular metabolism. Here, we demonstrate how the difference between bacteriostatic and bactericidal activities of the antibiotic chloramphenicol can be attributed to an antibiotic‐induced bacterial protective response: the stringent response. Chloramphenicol targets the ribosome to inhibit the growth of the Gram‐positive bacterium Bacillus subtilis . Intriguingly, we found that chloramphenicol becomes bactericidal in B. subtilis mutants unable to produce (p)ppGpp. We observed a similar (p)ppGpp‐dependent bactericidal effect of chloramphenicol in the Gram‐positive pathogen Enterococcus faecalis . In B. subtilis, chloramphenicol treatment induces (p)ppGpp accumulation through the action of the (p)ppGpp synthetase RelA. (p)ppGpp subsequently depletes the intracellular concentration of GTP and antagonizes GTP action. This GTP regulation is critical for preventing chloramphenicol from killing B. subtilis, as bypassing (p)ppGpp‐dependent GTP regulation potentiates chloramphenicol killing, while reducing GTP synthesis increases survival. Finally, chloramphenicol treatment protects cells from the classical bactericidal antibiotic vancomycin, reminiscent of the clinical phenomenon of antibiotic antagonism. Taken together, our findings suggest a role of (p)ppGpp in the control of the bacteriostatic and bactericidal activity of antibiotics in Gram‐positive bacteria, which can be exploited to potentiate the efficacy of existing antibiotics. Impact statement: The antimicrobial action of antibiotics can be broadly classified as bacteriostatic (i.e., inhibits growth) or bactericidal (i.e., lethality), which is largely considered as a property of the antibiotic. Here, we report that the Gram‐positive model bacterium Bacillus subtilis produces the signaling nucleotide (p)ppGpp in response to the bacteriostatic ribosome‐targeting antibiotic chloramphenicol. In the absence of this response, chloramphenicol mediates a strong bactericidal action. The description of the (p)ppGpp‐dependent bacteriostatic–bactericidal switch and its molecular mechanisms documented in this study provides a new insight into the understanding of antimicrobial properties, which can inspire the future development of antibacterial therapy by targeting bacterial nucleotide signaling.