A shared alarmone-GTP switch controls persister formation in bacteria.

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Physiology

Background:

• Persister cells are a subpopulation of bacteria that survive antibiotic treatment despite being genetically susceptible.
• The molecular mechanisms underlying the three known pathways of bacterial persistence (triggered, spontaneous, and antibiotic-induced) remain poorly understood.

Purpose of the Study:

• To elucidate the common molecular switch governing different bacterial persistence pathways in Bacillus subtilis.
• To investigate the role of guanosine tetra/penta-phosphate ((p)ppGpp) and GTP depletion in bacterial persistence.

Main Methods:

• Antibiotic time-kill assays were employed to assess bacterial survival.
• Single-cell approaches, including the development of a fluorescent GTP reporter, were utilized to visualize persister formation dynamics.
• Analysis of different alarmone synthetases responsible for (p)ppGpp production.

Main Results:

• All three pathways of bacterial persistence converge on a common switch involving the alarmone (p)ppGpp.
• (p)ppGpp accumulation promotes persistence by depleting intracellular GTP levels below a critical threshold.
• Single-cell imaging revealed a rapid, switch-like transition from growth to dormancy upon GTP depletion.

Conclusions:

• The antagonism between alarmones and GTP represents a fundamental mechanism driving bacterial persistence in Bacillus subtilis.
• This (p)ppGpp-GTP antagonism pathway is likely a widespread strategy for antibiotic survival in bacteria.
• Understanding this mechanism offers potential new avenues for combating antibiotic resistance.