Dataset Information

Covalent conjugation of a peptide triazole to HIV-1 gp120 enables intramolecular binding site occupancy.

ABSTRACT: The HIV-1 gp120 glycoprotein is the main viral surface protein responsible for initiation of the entry process and, as such, can be targeted for the development of entry inhibitors. We previously identified a class of broadly active peptide triazole (PT) dual antagonists that inhibit gp120 interactions at both its target receptor and coreceptor binding sites, induce shedding of gp120 from virus particles prior to host-cell encounter, and consequently can prevent viral entry and infection. However, our understanding of the conformational alterations in gp120 by which PT elicits its dual receptor antagonism and virus inactivation functions is limited. Here, we used a recently developed computational model of the PT-gp120 complex as a blueprint to design a covalently conjugated PT-gp120 recombinant protein. Initially, a single-cysteine gp120 mutant, E275CYU-2, was expressed and characterized. This variant retains excellent binding affinity for peptide triazoles, for sCD4 and other CD4 binding site (CD4bs) ligands, and for a CD4-induced (CD4i) ligand that binds the coreceptor recognition site. In parallel, we synthesized a PEGylated and biotinylated peptide triazole variant that retained gp120 binding activity. An N-terminally maleimido variant of this PEGylated PT, denoted AE21, was conjugated to E275C gp120 to produce the AE21-E275C covalent conjugate. Surface plasmon resonance interaction analysis revealed that the PT-gp120 conjugate exhibited suppressed binding of sCD4 and 17b to gp120, signatures of a PT-bound state of envelope protein. Similar to the noncovalent PT-gp120 complex, the covalent conjugate was able to bind the conformationally dependent mAb 2G12. The results argue that the PT-gp120 conjugate is structurally organized, with an intramolecular interaction between the PT and gp120 domains, and that this structured state embodies a conformationally entrapped gp120 with an altered bridging sheet but intact 2G12 epitope. The similarities of the PT-gp120 conjugate to the noncovalent PT-gp120 complex support the orientation of binding of PT to gp120 predicted in the molecular dynamics simulation model of the PT-gp120 noncovalent complex. The conformationally stabilized covalent conjugate can be used to expand the structural definition of the PT-induced "off" state of gp120, for example, by high-resolution structural analysis. Such structures could provide a guide for improving the subsequent structure-based design of inhibitors with the peptide triazole mode of action.

SUBMITTER: Emileh A

PROVIDER: S-EPMC4045323 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Covalent conjugation of a peptide triazole to HIV-1 gp120 enables intramolecular binding site occupancy.

Emileh Ali A Duffy Caitlin C Holmes Andrew P AP Rosemary Bastian Arangassery A Aneja Rachna R Tuzer Ferit F Rajagopal Srivats S Li Huiyuan H Abrams Cameron F CF Chaiken Irwin M IM

Biochemistry 20140519 21

The HIV-1 gp120 glycoprotein is the main viral surface protein responsible for initiation of the entry process and, as such, can be targeted for the development of entry inhibitors. We previously identified a class of broadly active peptide triazole (PT) dual antagonists that inhibit gp120 interactions at both its target receptor and coreceptor binding sites, induce shedding of gp120 from virus particles prior to host-cell encounter, and consequently can prevent viral entry and infection. Howeve ...[more]

PMID: 24801282

Similar Datasets

Project description:In an effort to identify broadly active inhibitors of HIV-1 entry into host cells, we previously reported a family of dodecamer triazole-peptide conjugates with nanomolar affinity for the viral surface protein gp120. This peptide class exhibits potent antiviral activity and the capacity to simultaneously inhibit interaction of the viral envelope protein with both CD4 and co-receptor. In this investigation, we minimized the structural complexity of the lead triazole inhibitor HNG-156 (peptide 1) to explore the limits of the pharmacophore that enables dual antagonism and to improve opportunities for peptidomimetic design. Truncations of both carboxy- and amino-terminal residues from the parent 12-residue peptide 1 were found to have minimal effects on both affinity and antiviral activity. In contrast, the central triazole(Pro)-Trp cluster at residues 6 and 7 with ferrocenyl-triazole(Pro) (Ftp) was found to be critical for bioactivity. Amino-terminal residues distal to the central triazole(Pro)-Trp sequence tolerated decreasing degrees of side chain variation upon approaching the central cluster. A peptide fragment containing residues 3-7 (Asn-Asn-Ile-Ftp-Trp) exhibited substantial direct binding affinity, antiviral potency, dual receptor site antagonism, and induction of gp120 structuring, all properties that define the functional signature of the parent compound 1. This active core contains a stereochemically specific hydrophobic triazole(Pro)-Trp cluster, with a short N-terminal peptide extension providing groups for potential main chain and side chain hydrogen bonding. The results of this work argue that the pharmacophore for dual antagonism is structurally limited, thereby enhancing the potential to develop minimized peptidomimetic HIV-1 entry inhibitors that simultaneously suppress binding of envelope protein to both of its host cell receptors. The results also argue that the target epitope on gp120 is relatively small, pointing to a localized allosteric inhibition site in the HIV-1 envelope that could be targeted for small-molecule inhibitor discovery.

Dataset Information

Covalent conjugation of a peptide triazole to HIV-1 gp120 enables intramolecular binding site occupancy.

Publications

Covalent conjugation of a peptide triazole to HIV-1 gp120 enables intramolecular binding site occupancy.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets