In Streptococcus mutans, how do competence-stimulating peptide and general quorum sensing differ?

In Streptococcus mutans, how do competence-stimulating peptide and general quorum sensing differ?

• A. CSP triggers genetic competence for DNA uptake via the ComDE system; AI-2 and other signals coordinate communal behaviors; both are quorum-sensing mechanisms.
• B. CSP inhibits genetic competence; AI-2 triggers virulence only.
• C. CSP triggers biofilm dispersal; ComDE system is involved; Not accurate.
• D. CSP is derived from the host; QS is microbial.

Answer: (A)

In Streptococcus mutans, the competence-stimulating peptide is a specific peptide pheromone that triggers genetic competence for DNA uptake by activating the ComDE two-component system. This is a targeted pathway: CSP binds ComD, a sensor kinase, which then phosphorylates ComE to turn on the competence genes needed for DNA uptake.

General quorum sensing, on the other hand, refers to broader cell-density–dependent signaling networks that regulate many communal behaviors. In S. mutans this often involves autoinducers like AI-2 (LuxS) and other signals that coordinate activities such as biofilm formation, metabolism, and virulence across the population, not just competence.

So CSP is a specialized signal driving competence via ComDE, while AI-2 and similar signals represent the wider quorum-sensing systems that control multiple community-wide behaviors. The other choices misstate CSP’s role (it does not inhibit competence, nor is it host-derived) or overstate its links (biofilm dispersal is not the primary established role of CSP).