HIV Fusion Inhibitor Peptide T-1249 Is Able To Insert or Adsorb to Lipidic Bilayers. Putative Correlation with Improved Efficiency

Abstract

T-1249 is a HIV fusion inhibitor peptide under clinical trials. Its interaction with biological membrane models (large unilamellar vesicles) was studied using fluorescence spectroscopy. A gp41 peptide that includes one of the hydrophobic terminals of T-1249 was also studied. Both peptides partition extensively to liquid-crystalline POPC (1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine) (DeltaG = -7.0 kcal/mol and -8.7 kcal/mol, for T-1249 and terminal peptide, respectively) and are located at the interface of the membrane. T-1249 is essentially in a random coil conformation in this lipidic medium, although a small alpha-helix contribution is present. When other lipid compositions are used (DPPC, POPG + POPC, and POPC + cholesterol) (DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and POPG (1-palmitoyl-2-oleyl-sn-glycero-3-[phospho-rac-(1-glycerol)), partition decreases, the most severe effect being the presence of cholesterol. Partition experiments and fluorescence resonance energy transfer analysis show that T-1249 adsorbs to cholesterol-rich membranes. The improved clinical efficiency of T-1249 relative to enfuvirtide (T20) may be related to its bigger partition coefficient and ability to adsorb to rigid lipidic areas on the cell surface, where most receptors are inserted. Moreover, adsorption to the sterol-rich viral membrane helps to increase the local concentration of the inhibitor peptide at the fusion site.

In Vivo Efficacy of Measles Virus Fusion Protein-Derived Peptides Is Modulated by the Properties of Self-Assembly and Membrane Residence

“…n.s., not significant; *, P Յ 0.01; **, P Յ 0.001; ***, P Յ 0.0001. of these peptides as antiviral fusion inhibitors (29). This effect was considered to be due to enhanced peptide-membrane interactions, as previously suggested for other antiviral fusion inhibitor peptides (39,40). Because of the hydrophobicity of the conjugated groups, it is assumed that the peptides insert into the membrane surface.…”

HIV gp41 C-terminal Heptad Repeat Contains Multifunctional Domains

“…von Laer and co-workers (37) have demonstrated that the wild-type T20 and the ANAA mutant T20 have similar anti-HIV-1 activities when both peptides are anchored to the target cell membrane by fusion to a transmembrane domain. Veiga et al (38) have shown that T-1249, an analogous peptide of T20, and its C-terminal peptide inhibit HIV-1 fusion by interacting with lipid bilayers. The tryptophan-rich (or lipid-binding) domain in the membrane proximal region of gp41 was shown to play important roles in HIV-1 fusion (22,36,39), because it may bind to the membrane surface (40) and participate in oligomerization of gp41 to form fusion pores in the membrane (23,35,41,42).…”

Addition of a cholesterol group to an HIV-1 peptide fusion inhibitor dramatically increases its antiviral potency

“…Further analysis of the antiviral potency of C34-Chol is shown in Table 4, where the antiviral activity of C34-Chol is compared, in two separate experiments, with underivatized C34, and with T20 and the second-generation FI T1249 (32,50), which is active against most enfuvirtide-resistant strains (23). Comparison of the IC 90 values, a stringent measure of antiviral potency, across a panel of HIV primary isolates from multiple subtypes shows that, depending on the strain tested, C34-Chol is 25-to 100-fold more potent than C34, 50-to 400-fold more potent than enfuvirtide, and 15-to 300-fold more potent than T1249.…”

“…To this aim, we have chosen C34 instead of T20 because the former has more potent antiviral activity in vitro, whereas the latter already includes a hydrophobic C-terminal segment that drives insertion into lipid membranes (32)(33)(34)(35)(36).…”

“…Because caveolin-1 is a cholesterol-binding protein (44), cholesterol is enriched in caveolae together with HIV-1. Finally, the increased ability to partition into cholesterolrich membranes has been proposed recently as the reason behind the increased clinical efficacy of the second-generation inhibitor T1249 with respect to T20 (32).…”