Interaction with lipid II induces conformational changes in bovicin HC5 structure

Area of Science:

• Microbiology
• Biochemistry
• Structural Biology

Background:

• Lantibiotics are a class of antimicrobial peptides with potential clinical applications.
• Understanding the mechanism of action of lantibiotics like Bovicin HC5 is crucial for expanding their use in medicine.
• Streptococcus bovis HC5 produces Bovicin HC5, which targets the lipid II precursor in bacterial cell walls.

Purpose of the Study:

• To investigate the interaction between Bovicin HC5 and lipid II using biophysical techniques.
• To elucidate the structural and conformational changes of Bovicin HC5 upon binding to lipid II.
• To assess the stability and functional implications of this interaction under varying conditions.

Main Methods:

• Tryptophan fluorescence spectroscopy to monitor conformational changes and binding.
• Circular dichroism spectroscopy to analyze secondary structure alterations.
• Model membrane systems were employed to simulate cellular environments.

Main Results:

• Bovicin HC5 directly binds to lipid II, causing a blue-shift in tryptophan fluorescence.
• The binding positions the Bovicin HC5 tryptophan residue near the twelfth acyl chain position of phospholipids.
• Lipid II binding induces significant conformational changes in Bovicin HC5.
• The Bovicin HC5-lipid II interaction remains stable even at pH 2.0.

Conclusions:

• Bovicin HC5 directly interacts with its target, lipid II, with a topology that varies with conditions.
• The observed interaction stability at extreme pH is a unique characteristic of Bovicin HC5.
• This extreme pH stability may be linked to Bovicin HC5's unique structure and could enhance its therapeutic applicability.