Effect of E1(64–81) hepatitis G peptide on the in vitro interaction of HIV-1 fusion peptide with membrane models

Abstract

One way to gain information about the fusogenic potential of virus-derived synthetic peptides is to examine their interfacial properties and subsequently to study them in monolayers and bilayers. Here, we characterize the physicochemical surface properties of the peptide E1(64–81), whose sequence is AQLVGELGSLYGPLSVSA. This peptide is derived from the E1 structural protein of GBV-C/HGV which was previously shown to inhibit leakage of vesicular contents caused by the HIV-1 fusion peptide (HIV-1 FP). Mixed isotherms of E1(64–81) and HIV-1 FP were obtained and their Brewster angle microscopy (BAM) and atomic force microscopy (AFM) images showed that the peptide mixture forms a different structure that is not present in the pure peptide images. Studies with lipid monolayers (1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) and 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG)) show that both peptides interact with all the lipids assayed but the effect that HIV-1 FP has on the monolayers is reduced in the presence of E1(64–81). Moreover, differential scanning calorimetry (DSC) experiments show the capacity of HIV-1 FP to modify the properties of the bilayer structure and the capacity of E1(64–81) to inhibit these modifications. Our results indicate that E1(64–81) interacts with HIV-1 FP to form a new structure, and that this may be the cause of the previously observed inhibition of the activity of HIV-1 FP by E1(64–81).