A two-component system signaling hub controls enterococcal membrane remodeling in response to daptomycin

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Daptomycin is a critical antibiotic for treating vancomycin-resistant enterococcal infections.
• Daptomycin resistance (DAP^R) emerges rapidly during therapy, linked to mutations in LiaFSR and cardiolipin synthases, altering membrane lipid composition.
• The precise molecular mechanisms behind these lipid changes and the sequence of mutational events remain unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms linking antibiotic exposure to membrane lipid remodeling in *Enterococcus faecalis*.
• To understand the role of specific enzymes and regulatory systems in daptomycin-induced membrane changes.
• To explain the sequential acquisition of mutations leading to daptomycin resistance.

Main Methods:

• Phenotypic analysis of *Enterococcus faecalis* membrane composition under daptomycin exposure.
• Investigation of the role of LtaS1 (lipoteichoic acid synthase) in glycolipid enrichment.
• Analysis of the regulatory control of LTA production by LiaFSR and SapRS two-component systems.

Main Results:

• *Enterococcus faecalis* phenotypically remodels its membrane in response to daptomycin, mimicking the lipid profile of resistant strains.
• Glycolipid enrichment is mediated by LtaS1, the primary lipoteichoic acid synthase.
• LiaFSR and SapRS systems directly link antibiotic sensing to membrane lipid remodeling, controlling LTA production.

Conclusions:

• A unifying mechanism is proposed where antibiotic sensing triggers membrane fortification via LTA remodeling.
• This phenotypic adaptation predisposes *E. faecalis* to acquire high-level daptomycin resistance.
• Understanding this interplay is crucial for combating antibiotic resistance in Gram-positive pathogens.