Creating an Artificial Tail Anchor as a Novel Strategy To Enhance the Potency of Peptide-Based HIV Fusion Inhibitors

J Virol. 2016 Dec 16;91(1):e01445-16. doi: 10.1128/JVI.01445-16. Print 2017 Jan 1.

Abstract

20 (enfuvirtide) and other peptides derived from the human immunodeficiency virus type 1 (HIV-1) gp41 C-terminal heptad repeat (CHR) region inhibit HIV fusion by binding to the hydrophobic grooves on the N-terminal heptad repeat (NHR) trimer and blocking six-helix-bundle (6-HB) formation. Several strategies focusing on the binding grooves of the NHR trimer have been adopted to increase the antiviral activity of the CHR peptides. Here, we developed a novel and simple strategy to greatly enhance the potency of the existing peptide-based HIV fusion inhibitors. First, we identified a shallow pocket adjacent to the groove in the N-terminal region of NHR trimer as a new drug target, and then we designed several short artificial peptides to fit this target. After the addition of IDL (Ile-Asp-Leu) to the C terminus of CHR peptide WQ or MT-WQ, the conjugated peptides, WQ-IDL and MT-WQ-IDL, showed much more potent activities than WQ and T20, respectively, in inhibiting HIV-1 IIIB infection. WQ-IDL and MT-WQ-IDL were also more effective than WQ in blocking HIV-1 Env-mediated membrane fusion and had higher levels of binding affinity with NHR peptide N46. We solved the crystal structure of the 6-HB formed by MT-WQ-IDL and N46 and found that, besides the N-terminal MT hook tail, the IDL tail anchor of MT-WQ-IDL also binds with the shallow hydrophobic pocket outside the groove of the NHR trimer, resulting in enhanced inhibition of HIV-1 fusion with the target cell. It is expected that this novel approach can be widely used to improve the potency of peptidic fusion inhibitors against other enveloped viruses with class I fusion proteins.

Importance: The hydrophobic groove of the human immunodeficiency virus type 1 (HIV-1) gp41 NHR trimer has been known as the classic drug target to develop fusion inhibitors derived from the gp41 CHR. Here, we developed a novel and simple strategy to improve the existing peptide-based HIV fusion inhibitors. We identified a shallow pocket adjacent to the groove in the NHR trimer and added a short artificial peptide consisting of three amino acids (IDL) to the C terminus of a fusion inhibitor to fit this new target. The inhibition activity of this new conjugated peptide was significantly enhanced, by 77-fold, making it much more potent than T20 (enfuvirtide) and suggesting that the IDL tail can be adopted for optimizing existing HIV-1 CHR peptide fusion inhibitors. This new approach of identifying a potential binding pocket outside the traditional target and creating an artificial tail anchor can be widely applied to design novel fusion inhibitors against other class I enveloped viruses, such as Middle East respiratory syndrome coronavirus (MERS-CoV).

Keywords: HIV; fusion inhibitor; gp41; peptide; six-helix bundle.

MeSH terms

  • Amino Acid Sequence
  • Cell Line, Tumor
  • Crystallography, X-Ray
  • Drug Design*
  • Enfuvirtide
  • HIV Envelope Protein gp41 / chemical synthesis*
  • HIV Envelope Protein gp41 / pharmacology
  • HIV Fusion Inhibitors / chemical synthesis*
  • HIV Fusion Inhibitors / pharmacology
  • HIV-1 / chemistry
  • HIV-1 / drug effects*
  • HIV-1 / growth & development
  • HIV-1 / metabolism
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Models, Molecular
  • Neuroglia / drug effects
  • Neuroglia / immunology
  • Neuroglia / virology
  • Peptide Fragments / chemical synthesis*
  • Peptide Fragments / pharmacology
  • Protein Interaction Domains and Motifs
  • Protein Multimerization
  • Protein Structure, Secondary
  • Sequence Alignment
  • Structure-Activity Relationship
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / immunology
  • T-Lymphocytes / virology
  • Virus Internalization / drug effects*

Substances

  • HIV Envelope Protein gp41
  • HIV Fusion Inhibitors
  • Peptide Fragments
  • Enfuvirtide