PolyGlcNAc-containing exopolymers enable surface penetration by non-motile Enterococcus faecalis.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Enterococcus faecalis is a major cause of hospital-acquired infections.
• Mechanisms of tissue invasion and surface penetration by E. faecalis are poorly understood.
• This bacterium is increasingly resistant to multiple drugs.

Purpose of the Study:

• To investigate the molecular mechanisms underlying Enterococcus faecalis surface penetration and tissue translocation.
• To identify key genes and metabolic pathways involved in E. faecalis invasion.
• To explore potential therapeutic targets for enterococcal infections.

Main Methods:

• Genetic screening of E. faecalis mutant strains.
• Molecular analyses of gene function (glnA, rpiA, epaX).
• Biochemical assays to determine polysaccharide synthesis and utilization of intermediates like UDP-GlcNAc.
• Functional assays assessing surface penetration and epithelial cell translocation.
• Complementation studies using exogenous polymeric N-acetylglucosamine (PNAG).

Main Results:

• E. faecalis produces exopolysaccharides containing β-1,6-linked poly-N-acetylglucosamine (polyGlcNAc) for surface penetration.
• Genes glnA, rpiA, and epaX are essential for E. faecalis penetration and translocation.
• GlnA and RpiA cooperate to produce UDP-GlcNAc, a precursor for polyGlcNAc synthesis by EpaX.
• Supplementation with PNAG rescued the penetration defect in epaX mutants.

Conclusions:

• The RpiA-GlnA-EpaX metabolic axis is crucial for synthesizing polyGlcNAc-containing exopolymers in E. faecalis.
• These exopolymers enable E. faecalis to penetrate surfaces and translocate through host tissues.
• Inhibiting polyGlcNAc biosynthesis or targeting this metabolic pathway presents a novel therapeutic strategy against E. faecalis infections.