pH-induced destabilization of lipid bilayers by a peptide from the VP3 protein of the capsid of hepatitis A virus.
The membrane destabilizing and fusogenic properties of the synthetic peptide VP3(110-121), corresponding to an immunogenic sequence of the hepatitis A virus (HAV) VP3 capsid protein, were studied. By tryptophan fluorescence and acryalmide quenching it was demonstrated that the peptide binds liposomes of POPC-SM-DPPE (47 + 39 + 14) and POPC-SM-DPPE-DOTAP (40 + 33 + 12 + 15) and penetrates the membrane, at both neutral and acidic pH (POPC = 1-palmitoyl-2-oleoylglycero-sn-3-phosphocholine; SM = sphingomyelin; DPPE = 1,2-dipalmitoylphosphatidylethanolamine; DOTAP = 1,2-dioleoyl-3-trimethylammoniumpropane). VP3(110-121) did not have membrane-destabilizing properties at neutral pH. Acid-induced destabilization of the vesicles was demonstrated by fluorescence techniques and dynamic light scattering. VP3(110-121) induced aggregation of POPC-SM-DPPE-DOTAP (40 + 33 + 12 + 15) vesicles, lipid mixing and leakage of vesicle contents, all consistent with fusion of vesicles. In POPC-SM-DPPE (47 + 39 + 14) vesicles, at acidic pH, VP3(110-121) induced membrane destabilization with leakage of contents but without aggregation of vesicles or lipid mixing. The peptide only showed fusogenic properties when bound to the vesicles at neutral pH before acidification to pH below 6.0, and no effect was seen if the peptide was added to vesicles already set at acidic pH. These results may have physiological significance in the mechanism of infection of host hepatic cells by HAV.
Department of Physical Chemistry, School of Pharmacy, University of Barcelona, Spain.
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Chávez
M A
MA
Busquets
M
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Pujol
M A
MA
Alsina
Y
Y
Cajal
D002213:Capsid / Q000494:pharmacology*; D036022:Capsid Proteins; D017957:Hepatitis A Virus, Human; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers; D008561:Membrane Fusion; D014760:Viral Fusion Proteins / Q000494:pharmacology*
D036022:Capsid Proteins; D008051:Lipid Bilayers; D014760:Viral Fusion Proteins