Subpopulation-specific transcriptome analysis of competence-stimulating-peptide-induced Streptococcus mutans.

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Competence development in Streptococcus mutans is regulated by competence-stimulating peptide (CSP).
• This process is transient and involves only a subpopulation of cells.
• The activation of DNA uptake machinery is short-lived, ceasing 3-4 hours post-induction.

Purpose of the Study:

• To investigate the heterogeneity of competence development in Streptococcus mutans.
• To analyze gene expression differences between competent and non-competent subpopulations.
• To understand the fate of cells initiating competence.

Main Methods:

• Utilized bacterial flow-cytometric sorting guided by a ComX-green fluorescent protein (ComX-GFP) reporter.
• Performed subpopulation-specific transcriptome analysis on sorted competent and non-competent fractions.
• Confirmed gene expression patterns using GFP reporter strains and fluorescence microscopy.

Main Results:

• Successfully enriched transcripts for comX and its downstream genes in the competent fraction.
• Identified ComDE and the ComR/S regulator system exclusively in the competent subpopulation.
• Observed that bacteriocin-related genes were expressed uniformly across all cells, while some ComX-expressing cells underwent autolysis.

Conclusions:

• All Streptococcus mutans cells respond to CSP by activating bacteriocin-related genes.
• Cells initiating ComX expression diverge into either competent cells capable of DNA uptake or cells undergoing lysis.
• This divergence leads to significant intrapopulation diversity during competence development.