Investigating molecular recognition and biological function at interfaces using piscidins, antimicrobial peptides...

Area of Science:

• Biochemistry
• Structural Biology
• Antimicrobial Peptides

Background:

• Piscidins are amphipathic cationic antimicrobial peptides found in fish.
• Understanding structural motifs is crucial for functional diversity in amidated and non-amidated isoforms.

Purpose of the Study:

• To characterize functional and structural similarities and differences between amidated and non-amidated piscidins 1 and 3.
• To elucidate structural motifs involved in biological activity and functional diversity.

Main Methods:

• Antimicrobial and hemolytic assays were performed to evaluate peptide potency and toxicity.
• High-resolution solid-state NMR and circular dichroism were used to determine peptide structure and orientation in lipid bilayers.

Main Results:

• Piscidins 1 and 3 adopt an alpha-helical structure and orient parallel to the lipid bilayer surface.
• Solid-state NMR revealed fast, large-amplitude backbone motions in piscidins.
• Piscidin 1 exhibited higher antimicrobial potency than piscidin 3; amidation did not impact activity.

Conclusions:

• The topology and fast dynamics of piscidins are likely related to their mechanism of action.
• Functional and structural similarities exist between amidated and non-amidated piscidin isoforms.