Membrane vesicle production via cell-to-cell communication-induced autolysis in Streptococcus mutans

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Cell Biology

Background:

• Membrane vesicles (MVs) are released by bacteria and play roles in inter-bacterial and bacterial-host interactions.
• In Gram-positive bacteria, cytoplasmic MV (CMV) release requires cell wall degradation or damage.
• The mechanism triggering CMV production in *Streptococcus mutans*, a dental caries agent, was previously unknown.

Purpose of the Study:

• To elucidate the mechanism by which *Streptococcus mutans* induces CMV release.
• To investigate the role of the Com system in CMV production and its impact on bacterial populations.

Main Methods:

• Investigated CMV release in *S. mutans* using the Com system (cell-to-cell communication).
• Analyzed the role of autolysin LytF in CMV release.
• Utilized electron microscopy to observe CMV release and associated cell death.
• Compared protein profiles of CMVs induced via different methods.

Main Results:

• The Com system regulates CMV release in *S. mutans*, primarily dependent on LytF autolysin.
• CMV release is associated with cell death in a subpopulation of bacterial cells.
• Com system-induced CMVs contain specific cytoplasmic proteins and influence biofilm formation differently.

Conclusions:

• Cell-to-cell communication via the Com system triggers cell death-mediated MV formation in *S. mutans*.
• This regulated MV release benefits the surviving bacterial population, particularly in biofilm formation.
• This study provides the first evidence of cell-to-cell communication regulating MV formation in Gram-positive bacteria.