Characterization of MreCD in Streptococcus mutans

Area of Science:

• Bacterial physiology and cell biology
• Microbial pathogenesis
• Molecular microbiology

Background:

• Cell shape and division are vital for bacterial survival.
• The regulatory mechanisms for these processes in *Streptococcus mutans*, a key dental caries pathogen, are not well understood.

Purpose of the Study:

• To characterize the function of the MreC and MreD proteins (MreCD) in *Streptococcus mutans*.
• To elucidate the role of MreCD in bacterial cell morphology, protein interactions, gene expression, and biofilm formation.

Main Methods:

• Cell morphology imaging
• Bacterial two-hybrid assays for protein interactions
• Transcriptomics and proteomics
• Biofilm formation assays
• Competition assays

Main Results:

• Mutants lacking *mreCD* exhibited altered cell shape, becoming rounder than wild-type.
• MreCD proteins interact with other cell elongation factors.
• Absence of *mreCD* altered the surface proteome and sucrose-mediated biofilm architecture.
• Loss of *mreCD* affected bacteriocin gene expression and reduced competitive fitness against commensal bacteria.

Conclusions:

• Cell elongation proteins MreCD are essential for normal *Streptococcus mutans* physiology.
• These findings provide a basis for further research into MreCD and related proteins in *S. mutans*.