Membrane-Perturbing Domains of HIV Type 1 Glycoprotein 41

Abstract

Structural and functional studies were performed to assess the membrane actions of peptides based on HIV-1 glycoprotein 41,000 (gp41). Previous site-directed mutagenesis of gp41 has shown that amino acid changes in either the N-terminal fusion or N-leucine zipper region depressed viral infection and syncytium formation, while modifications in the C-leucine zipper domain both increased and decreased HIV fusion. Here, synthetic peptides were prepared corresponding to the N-terminal fusion region (FP-I; gp41 residues 519-541), the nearby N-leucine zipper domain (DP-107; gp41 residues 560-597), and the C-leucine zipper domain (DP-178; gp41 residues 645-680). With erythrocytes, FP-I or DP-107 induced dose-dependent hemolysis and promoted cell aggregation; FP-I was more hemolytic than DP-107, but each was equally effective in aggregating cells. DP-178 produced neither hemolysis nor aggregation, but blocked either FP-I- or DP-107-induced hemolysis and aggregation. Combined with previous nuclear magnetic resonance and Fourier transform infrared spectroscopic results, circular dichroism (CD) spectroscopy showed that the alpha-helicity for these peptides in solution decreased in the order: DP-107 >> DP-178 > FP-I. CD analysis also indicated binding of DP-178 to either DP-107 or FP-I. Consequently, DP-178 may inhibit the membrane actions mediated by either FP-I or DP-107 through direct peptide interactions in solution. These peptide results suggest that the corresponding N-terminal fusion and N-leucine zipper regions participate in HIV infection, by promoting membrane perturbations underlying the merging of the viral envelope with the cell surface. Further, the C-leucine zipper domain in "prefusion" HIV may inhibit these membrane activities by interacting with the N-terminal fusion and N-leucine zipper domains in unactivated gp41. Last, exogenous DP-178 may bind to the N-terminal and N-leucine zipper domains of gp41 that become exposed on HIV stimulation, thereby preventing the fusogenic actions of these gp41 regions leading to infection.

Proteoliposomal formulations of an HIV-1 gp41-based miniprotein elicit a lipid-dependent immunodominant response overlapping the 2F5 binding motif

“…This effect was more pronounced for the 208 nm band in simple proteoliposome preparations. The shift of the positive band, together with the Ө 222 /Ө 208 ellipticity ratio >1, would support the existence of helix-helix interactions such as those described for heterodimeric coiled-coils48495051 and/or transmembrane helical bundles52. Seemingly, the protein in solution shows a Ө 222 /Ө 208 ellipticity ratio <1, which would be consistent with the disruption of helix-helix interactions or monomeric alpha-helix50.…”

Development of resistance to VIR-353 with cross-resistance to the natural HIV-1 entry virus inhibitory peptide (VIRIP)

“…However, T20 and other gp41 targeting peptides have also been found to display antihemolytic activity [17,35]. Assays evaluating synthetic peptide-peptide gp41 may not truly mimic the complex interaction of gp41 in its natural conformations.…”

Different from the HIV Fusion Inhibitor C34, the Anti-HIV Drug Fuzeon (T-20) Inhibits HIV-1 Entry by Targeting Multiple Sites in gp41 and gp120

“…Extension of FP to include partial sequence of NHR region results in significant enhancement of FP-mediated membrane fusion, suggesting that NHR has a synergistic role in FP-mediated fusogenic activity (57). Mobley et al (58) demonstrated that T-20 can block hemolysis and cell aggregation induced by FP and the N-peptide fusion inhibitor T-21, implying the interaction of T-20 with the FP. It is plausible that T-20 inhibits the viral fusion by affecting the membrane perturbations associated with the interactions of FP and NHR, which underlie the merging of the viral envelope with the target cell membrane.…”