SpxB-mediated H2 O2 induces programmed cell death in Streptococcus sanguinis

Area of Science:

• Microbiology
• Cell Biology
• Biochemistry

Background:

• Streptococcus sanguinis is a common oral bacterium.
• It produces hydrogen peroxide (H2 O2) via pyruvate oxidase (SpxB).
• H2 O2 influences biofilm formation, eDNA release, and cell death in S. sanguinis.

Purpose of the Study:

• To investigate the mechanism of cell death induced by H2 O2 in S. sanguinis.
• To determine if S. sanguinis exhibits hallmarks of eukaryotic apoptosis.
• To identify genetic factors involved in H2 O2-induced cell death.

Main Methods:

• Exposure of S. sanguinis to endogenous and exogenous H2 O2.
• Analysis of biochemical and morphological changes indicative of apoptosis.
• Gene expression analysis of DNA repair genes (comEA, recA, dnaC, dinG, pcrA).

Main Results:

• S. sanguinis displayed characteristic features of eukaryotic apoptosis upon H2 O2 exposure.
• Observed events included DNA fragmentation, chromosome condensation, and altered membrane potential.
• Decreased expression of DNA repair genes was noted in wild-type compared to spxB mutant strains.

Conclusions:

• Endogenous H2 O2 is a key mediator of apoptosis in Streptococcus sanguinis.
• H2 O2-induced cell death in S. sanguinis shares similarities with eukaryotic programmed cell death.
• The findings provide insights into bacterial programmed cell death mechanisms.