Membrane interactions of the synthetic N-terminal peptide of HIV-1 gp41 and its structural analogs

Abstract

Structural and functional studies assessed the membrane actions of the N terminus of HIV-1 glycoprotein 41000 (gp41). Earlier site-directed mutagenesis has shown that key amino acid changes in this gp41 domain inhibit viral infection and syncytia formation. Here, a synthetic peptide corresponding to the N terminus of gp41 (FP; 23 residues, 519-541), and also FP analogs (FP520V/E with Val-->Glu at residue 520; FP527L/R with Leu-->Arg at 527; FP529F/Y with Phe-->Tyr at 529; and FPCLP1 with FP truncated at 525) incorporating these modifications were prepared. When added to human erythrocytes at physiologic pH, the lytic and aggregating activities of the FP analogs were much reduced over those with the wild-type FP. With resealed human erythrocyte ghosts, the lipid-mixing activities of the FP analogs were also substantially depressed over that with the wild-type FP. Combined with results from earlier studies, theoretical calculations using hydrophobic moment plot analysis and physical experiments using circular dichroism and Fourier transform infrared spectroscopy indicate that the diminished lysis and fusion noted for FP analogs may be due to altered peptide-membrane lipid interactions. These data confirm that the N-terminal gp41 domain plays critical roles in the cytolysis and fusion underlying HIV-cell infection.

Membrane-Transferring Regions of gp41 as Targets for HIV-1 Fusion Inhibition and Viral Neutralization

“…These studies not only confirm the predicted high affinity of MTRs for the membrane interface, but also support their role as promoters of lipid bilayer destabilization [12,13,34,[36][37][38]. In principle MTR-s might promote fusion by reducing the formation energies of the lipidic intermediates of fusion, and/or by accelerating the opening of fusion pores [39][40][41].…”

The HIV Fusion Peptide Adopts Intermolecular Parallel β-Sheet Structure in Membranes when Stabilized by the Adjacent N-Terminal Heptad Repeat: A 13C FTIR Study

“…These studies have shown that the FP aggregates in solution, 23,[27][28][29][30] and readily binds to and inserts into membranes, 23,27,[29][30][31][32][33][34] aggregating therein. 23,30,[33][34][35] Additionally, the FP induces aggregation, 23,31,36,37 and destabilization, 23,[27][28][29][30][31][34][35][36][37][38][39][40][41][42] of membrane vesicles; functions that allude to a direct role during viral fusion. Structural characterization of the discrete FP has revealed seemingly paradoxical data; a-helix or b-structure.…”

“…Structural characterization of the discrete FP has revealed seemingly paradoxical data; a-helix or b-structure. 27,[29][30][31][32][33][34][35][37][38][39][41][42][43][44][45] This apparent dichotomy may be explained by structural plasticity inherent in the FP based on its primary sequence, which is highly enriched in Gly and Ala (Figure 2). During the fusion event, both structures may be relevant and serve specific Figure 1.…”

Solid-State Nuclear Magnetic Resonance Evidence for Parallel and Antiparallel Strand Arrangements in the Membrane-Associated HIV-1 Fusion Peptide

“…In each of these soluble ectodomain structures, the protein is trimeric, and its three N-termini (corresponding to about residue 30 in the whole envelope protein) are in close proximity at the end of an in-register helical coiled-coil. These structures end several residues C-terminal of the fusion peptide, and it has therefore been hypothesized that during viral/target cell fusion, at least three fusion peptides insert into the target cell membrane with their C-termini in close proximity.A variety of experimental methods have shown that both the HIV-1 and influenza fusion peptides can assume helical or nonhelical structures in their membrane-associated forms (6,9,10,14,15,17,18,(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) 1,phosphatidylethanolamine; N-Rh-PE, N-(lissamine rhodamine B sulfonyl)phosphatidylethanolamine; PDB, Protein Data Bank; PI, phosphatidylinositol; POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine; POPE, 1-palmitoyl-2-oleoyl-snglycero-3-phosphoethanolamine; POPS, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine; rf, radio frequency; RET, resonance energy transfer; REDOR, rotational-echo double resonance; RFDR, radio frequencydriven dipolar recoupling; SEDRA, simple excitation for the dephasing of rotational-echo amplitudes; SIMPSON, simulation program for solidstate NMR spectroscopy; TFA, trifluoroacetic acid; TPPM, two pulse phase modulation; 1D, one dimensional; 2D, two dimensional. …”