A shared alarmone-GTP switch underlies triggered and spontaneous persistence

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Physiology

Background:

• Bacterial persisters are non-growing cells tolerant to antibiotics.
• Understanding the molecular basis of persister formation is crucial for combating antibiotic resistance.
• Existing knowledge categorizes persisters into triggered, spontaneous, and antibiotic-induced types.

Purpose of the Study:

• To elucidate the common molecular determinants underlying different types of bacterial persistence.
• To investigate the role of the alarmone guanosine tetraphosphate (ppGpp) in persister formation.
• To characterize the mechanisms of triggered, spontaneous, and antibiotic-induced persistence in Gram-positive bacteria.

Main Methods:

• Investigated persistence mechanisms in a Gram-positive bacterium.
• Utilized a fluorescent GTP reporter to visualize single-cell GTP dynamics during persister formation.
• Analyzed the roles of alarmone synthetases (Rel, SasB, SasA) and ppGpp in different persistence pathways.

Main Results:

• Identified a common persistence switch mediated by ppGpp across triggered, spontaneous, and antibiotic-induced persisters.
• Demonstrated that ppGpp accumulation depletes intracellular GTP, leading to a rapid switch from growth to dormancy.
• Showcased distinct alarmone synthesis pathways for each persistence type, converging on ppGpp production.

Conclusions:

• Alarmone-GTP antagonism is a conserved mechanism driving bacterial persistence and antibiotic survival.
• ppGpp-mediated GTP depletion is essential for the switch-like dynamics leading to persister formation.
• This mechanism is likely widespread in Gram-positive bacteria and potentially other microbial species.