Synthetic “interface” peptides alter dimeric assembly of the HIV 1 and 2 proteases

• Published in: Protein science Vol. 1; no. 10; pp. 1244 - 1253
• Main Authors: Babé, Lilia M., Rosé, Jason, Craik, Charles S.
• Format: Journal Article
• Language: English
• Published: Bristol Cold Spring Harbor Laboratory Press 01.10.1992
• Subjects: AIDS/HIV; Amino Acid Sequence; Aspartic Acid Endopeptidases - chemistry; aspartyl protease; assembly; Avian Sarcoma Viruses - enzymology; Cross-Linking Reagents; cross‐linking; dimer interface; dimers; dissociation; enzyme inhibition; HIV Protease - chemistry; HIV Protease Inhibitors - pharmacology; HIV-2 - enzymology; HIV1 protease; HIV2 protease; human immunodeficiency virus 1; Immunoblotting; Molecular Sequence Data; peptide; Peptide Fragments - chemical synthesis; Peptide Fragments - chemistry; peptides; Protein Folding; proteinase; refolding; synthetic; tethered dimer
• ISSN: 0961-8368; 1469-896X
• DOI: 10.1002/pro.5560011003

Retroviral proteases are obligate homodimers and play an essential role in the viral life cycle. Dissociation of dimers or prevention of their assembly may inactivate these enzymes and prevent viral maturation. A salient structural feature of these enzymes is an extended interface composed of interdigitating N‐ and C‐terminal residues of both monomers, which form a four‐stranded β‐sheet. Peptides mimicking one β‐strand (residues 95–99), or two β‐strands (residues 1–5 plus 95–99 or 95–99 plus 95–99) from the human immunodeficiency virus 1 (HIV1) interface were shown to inhibit the HIV1 and 2 proteases (PRs) with IC50's in the low micromolar range. These interface peptides show cognate enzyme preference and do not inhibit pepsin, renin, or the Rous sarcoma virus PR, indicating a degree of specificity for the HIV PRs. A tethered HIV1 PR dimer was not inhibited to the same extent as the wild‐type enzymes by any of the interface peptides, suggesting that these peptides can only interact effectively with the interface of the two‐subunit HIV PR. Measurements of relative dissociation constants by limit dilution of the enzyme show that the one‐strand peptide causes a shift in the observed Kd for the HIV1 PR. Both one‐ and two‐strand peptides alter the monomer/dimer equilibrium of both HIV1 and HIV2 PRs. This was shown by the reduced cross‐linking of the HIV2 PR by disuccinimidyl suberate in the presence of the interface peptides. Refolding of the HIV1 and HIV2 PRs with the interface peptides shows that only the two‐strand peptides prevent the assembly of active PR dimers. Although both one‐ and two‐strand peptides seem to affect dimer dissociation, only the two‐strand peptides appear to block assembly. The latter may prove to be more effective backbones for the design of inhibitors directed toward retroviral PR dimerization in vivo.