pH-Activated fusogenic transmembrane LV-peptides.

Area of Science:

• Biochemistry
• Biophysics
• Molecular Biology

Background:

• LV-peptides are synthetic analogs of viral fusion protein transmembrane domains.
• Their fusogenicity is linked to the structural plasticity of their hydrophobic core.
• The role of flanking charged residues in peptide fusogenicity was previously unexplored.

Purpose of the Study:

• To investigate the functional importance of positively charged flanking residues in LV-peptide fusogenicity.
• To compare the fusogenic properties of peptides with terminal lysine (Lys) versus histidine (His) triplets.
• To explore potential applications of pH-dependent fusogenic peptides.

Main Methods:

• Synthesis of LV-peptide variants with terminal His and/or Lys triplets.
• Liposome fusion assays to measure peptide fusogenicity.
• pH-dependent activity measurements and titration curve analysis.

Main Results:

• Peptides with His triplets exhibited pH-dependent liposome fusion, triggered at acidic pH.
• The pH dependence followed a sigmoidal curve, with a midpoint near histidine's pKa.
• Fusogenicity required positively charged residues at both peptide termini.
• The dependence of fusogenicity on the hydrophobic core sequence was maintained in His-flanked peptides at low pH.

Conclusions:

• Both structural flexibility of the hydrophobic core and positive charges at the termini are essential for LV-peptide function in lipid mixing.
• Histidine-flanked LV-peptides demonstrate pH-dependent fusogenicity, offering potential for targeted applications.
• These pH-dependent peptides may be valuable tools for lipofection of eukaryotic cells.