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Origins of resistance to the HIVgp41 viral entry inhibitor T20.

ABSTRACT: Peptide T20, which targets the HIV protein gp41, represents the first approved member of the class of HIV drugs known as membrane fusion inhibitors. However, mechanisms which lead to resistance through clinical use of T20 are not well-understood because the structure of the bound complex remains undetermined. In this report, an atomic-level model of a T20-gp41 complex embedded in an explicit DOPC membrane was constructed, and molecular dynamics simulations, followed by binding energy analysis (MM-GBSA method), were performed to delineate structural and energetic features that contribute to drug resistance. Per-residue binding footprints for T20 with wild-type gp41 reveal strong intermolecular van der Waals, Coulombic, and H-bond interactions in striking agreement with clinically observed resistance patterns. In addition, seven deleterious gp41 point mutations (L33Q, L33S, G36V, I37K, V38E, Q40H, and Q40K) were simulated, and all correctly exhibited decreases in the level of binding, including the fact that L33Q and Q40K are most detrimental. Six of the seven simulations yield good quantitative agreement (r(2) = 0.72; N = 6) with available experimental fold resistance data. Results from energy decomposition, heat map analysis, and differential (mutant minus wild-type) footprinting indicate the following. (1) Mutations disrupt intermolecular H-bonding and reduce the level of favorable contact with gp41 at M19. (2) Charged mutations (I37K, Q40K, and V38E) lead to significant Coulombic changes that weaken favorable van der Waals interactions. (3) Q40K is more detrimental than I37K because of interaction differences with a polar/charged patch on T20 in the initial (wild-type) state. (4) Resistance for L33S versus L33Q likely involves side chain packing differences in the final (mutated) state. A valuable finding of the work involves identification of favorable interactions among the C-terminal end of T20 (WNWF motif), residues on gp41 (including the fusion peptide), and headgroups in the adjacent membrane. The results suggest a complete T20 binding site would contribute to a stable complex, which could help to explain why prior studies, which employed truncated gp41 constructs, reported that C-terminal T20 residues may not interact with gp41. A hypothesis resulting from this study is that peptides could be designed to increase the level of favorable contact with both the membrane and gp41 which would lead to enhanced activity.

SUBMITTER: McGillick BE

PROVIDER: S-EPMC2867330 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Origins of resistance to the HIVgp41 viral entry inhibitor T20.

McGillick Brian E BE Balius Trent E TE Mukherjee Sudipto S Rizzo Robert C RC

Biochemistry 20100501 17

Peptide T20, which targets the HIV protein gp41, represents the first approved member of the class of HIV drugs known as membrane fusion inhibitors. However, mechanisms which lead to resistance through clinical use of T20 are not well-understood because the structure of the bound complex remains undetermined. In this report, an atomic-level model of a T20-gp41 complex embedded in an explicit DOPC membrane was constructed, and molecular dynamics simulations, followed by binding energy analysis (M ...[more]

PMID: 20230061

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Project description:The peptide drug enfuvirtide (T20) is the only viral fusion inhibitor used in combination therapy for HIV-1 infection, but it has relatively low antiviral activity and easily induces drug resistance. Emerging studies demonstrate that lipopeptide-based fusion inhibitors, such as LP-11 and LP-19, which mainly target the gp41 pocket site, have greatly improved antiviral potency and in vivo stability. In this study, we focused on developing a T20-based lipopeptide inhibitor that lacks pocket-binding sequence and targets a different site. First, the C-terminal tryptophan-rich motif (TRM) of T20 was verified to be essential for its target binding and inhibition; then, a novel lipopeptide, termed LP-40, was created by replacing the TRM with a fatty acid group. LP-40 showed markedly enhanced binding affinity for the target site and dramatically increased inhibitory activity on HIV-1 membrane fusion, entry, and infection. Unlike LP-11 and LP-19, which required a flexible linker between the peptide sequence and the lipid moiety, addition of a linker to LP-40 sharply reduced its potency, implying different binding modes with the extended N-terminal helices of gp41. Also, interestingly, LP-40 showed more potent activity than LP-11 in inhibiting HIV-1 Env-mediated cell-cell fusion while it was less active than LP-11 in inhibiting pseudovirus entry, and the two inhibitors displayed synergistic antiviral effects. The crystal structure of LP-40 in complex with a target peptide revealed their key binding residues and motifs. Combined, our studies have not only provided a potent HIV-1 fusion inhibitor, but also revealed new insights into the mechanisms of viral inhibition.IMPORTANCE T20 is the only membrane fusion inhibitor available for treatment of viral infection; however, T20 requires high doses and has a low genetic barrier for resistance, and its inhibitory mechanism and structural basis remain unclear. Here, we report the design of LP-40, a T20-based lipopeptide inhibitor that has greatly improved anti-HIV activity and is a more potent inhibitor of cell-cell fusion than of cell-free virus infection. The binding modes of two classes of membrane-anchoring lipopeptides (LP-40 and LP-11) verify the current fusion model in which an extended prehairpin structure bridges the viral and cellular membranes, and their complementary effects suggest a vital strategy for combination therapy of HIV-1 infection. Moreover, our understanding of the mechanism of action of T20 and its derivatives benefits from the crystal structure of LP-40.

Project description:BackgroundPIE12-trimer is a highly potent D-peptide HIV-1 entry inhibitor that broadly targets group M isolates. It specifically binds the three identical conserved hydrophobic pockets at the base of the gp41 N-trimer with sub-femtomolar affinity. This extremely high affinity for the transiently exposed gp41 trimer provides a reserve of binding energy (resistance capacitor) to prevent the viral resistance pathway of stepwise accumulation of modest affinity-disrupting mutations. Such modest mutations would not affect PIE12-trimer potency and therefore not confer a selective advantage. Viral passaging in the presence of escalating PIE12-trimer concentrations ultimately selected for PIE12-trimer resistant populations, but required an extremely extended timeframe (> 1 year) in comparison to other entry inhibitors. Eventually, HIV developed resistance to PIE12-trimer by mutating Q577 in the gp41 pocket.ResultsUsing deep sequence analysis, we identified three mutations at Q577 (R, N and K) in our two PIE12-trimer resistant pools. Each point mutant is capable of conferring the majority of PIE12-trimer resistance seen in the polyclonal pools. Surface plasmon resonance studies demonstrated substantial affinity loss between PIE12-trimer and the Q577R-mutated gp41 pocket. A high-resolution X-ray crystal structure of PIE12 bound to the Q577R pocket revealed the loss of two hydrogen bonds, the repositioning of neighboring residues, and a small decrease in buried surface area. The Q577 mutations in an NL4-3 backbone decreased viral growth rates. Fitness was ultimately rescued in resistant viral pools by a suite of compensatory mutations in gp120 and gp41, of which we identified seven candidates from our sequencing data.ConclusionsThese data show that PIE12-trimer exhibits a high barrier to resistance, as extended passaging was required to develop resistant virus with normal growth rates. The primary resistance mutation, Q577R/N/K, found in the conserved gp41 pocket, substantially decreases inhibitor affinity but also damages viral fitness, and candidate compensatory mutations in gp160 have been identified.

Project description:Development of highly effective antivirals that are robust to viral evolution is a practical strategy for combating the continuously evolved severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Inspired by viral multistep entry process, we here focus on developing a bispecific SARS-CoV-2 entry inhibitor, which acts on the cell receptor angiotensin converting enzyme 2 (ACE2) and viral S2 fusion protein. First, we identified a panel of diverse spike (S) receptor-binding domains (RBDs) and found that the RBD derived from Guangdong pangolin coronavirus (PCoV-GD) possessed the most potent antiviral potency. Next, we created a bispecific inhibitor termed RBD-IPB01 by genetically linking a peptide fusion inhibitor IPB01 to the C-terminal of PCoV-GD RBD, which exhibited greatly increased antiviral potency via cell membrane ACE2 anchoring. Promisingly, RBD-IPB01 had a uniformly bifunctional inhibition on divergent pseudo- and authentic SARS-CoV-2 variants, including multiple Omicron subvariants. RBD-IPB01 also showed consistently cross-inhibition of other sarbecoviruses, including SARS-CoV, PCoV-GD, and Guangxi pangolin coronavirus (PCoV-GX). RBD-IPB01 displayed low cytotoxicity, high trypsin resistance, and favorable metabolic stability. Combined, our studies have provided a tantalizing insight into the design of broad-spectrum and potent antiviral agent. IMPORTANCE Ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) evolution and spillover potential of a wide variety of sarbecovirus lineages indicate the importance of developing highly effective antivirals with broad capability. By directing host angiotensin converting enzyme 2 receptor and viral S2 fusion protein, we have created a dual-targeted virus entry inhibitor with high antiviral potency and breadth. The inhibitor receptor-binding domain (RBD)-IPB01 with the Guangdong pangolin coronavirus (PCoV-GD) spike RBD and a fusion inhibitor IPB01 displays bifunctional cross-inhibitions on pseudo- and authentic SARS-CoV-2 variants including Omicron, as well as on the sarbecoviruses SARS-CoV, PCoV-GD, and Guangxi pangolin coronavirus. RBD-IPB01 also efficiently inhibits diverse SARS-CoV-2 infection of human Calu-3 cells and blocks viral S-mediated cell-cell fusion with a dual function. Thus, the creation of such a bifunctional inhibitor with pan-sarbecovirus neutralizing capability has not only provided a potential weapon to combat future SARS-CoV-2 variants or yet-to-emerge zoonotic sarbecovirus, but also verified a viable strategy for the designing of antivirals against infection of other enveloped viruses.

Dataset Information

Origins of resistance to the HIVgp41 viral entry inhibitor T20.

Publications

Origins of resistance to the HIVgp41 viral entry inhibitor T20.

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