Novel lactoferrampin antimicrobial peptides derived from human lactoferrin

Area of Science:

• Biochemistry
• Molecular Biology
• Antimicrobial Peptides

Background:

• Human lactoferrin is an iron-binding protein containing a cationic N-terminal lobe.
• Lactoferrampin is a novel antimicrobial peptide derived from human lactoferrin.
• The bovine lactoferrin-derived lactoferrampin sequence is inactive independently.

Purpose of the Study:

• To investigate the structure-activity relationship of human lactoferrampin.
• To determine the impact of charge and N-terminal modifications on antimicrobial activity.
• To elucidate the mechanism of membrane interaction.

Main Methods:

• Chemical synthesis of human lactoferrampin variants.
• Assessment of antibacterial and Candidacidal activity.
• Solution structure determination using SDS micelles.
• Differential scanning calorimetry and fluorescence spectroscopy.

Main Results:

• Increasing the net positive charge enhanced human lactoferrampin's antibacterial and antifungal activity.
• N-terminal helix capping (DAI) did not affect human lactoferrampin activity, unlike bovine lactoferrampin.
• Structural analysis revealed an amphipathic N-terminal helix and a flexible cationic C-terminus.
• Peptide insertion into lipid bilayers was confirmed, mediated by a hydrophobic patch.

Conclusions:

• Human lactoferrampin's antimicrobial efficacy is modulated by its C-terminal charge.
• Structural differences exist in the activity modulation between human and bovine lactoferrampin.
• The peptide interacts with and inserts into phospholipid bilayers via hydrophobic interactions.