Design of a Gag pentapeptide analogue that binds human cyclophilin A more efficiently than the entire capsid protein: new insights for the development of novel anti-HIV-1 drugs.
Cyclophilin A (hCyp-18), a ubiquitous cytoplasmic peptidyl-prolyl cis/trans isomerase (PPIase), orchestrates HIV-1 core packaging. hCyp-18, incorporated into the virion, enables core uncoating and RNA release and consequently plays a critical role in the viral replication process. hCyp-18 specifically interacts with a single exposed loop of the Gag polyprotein capsid domain via a network of nine hydrogen bonds which mainly implicates a 7-mer fragment of the loop. As previously reported, the corresponding linear heptapeptide Ac-Val-His-Ala-Gly-Pro-Ile-Ala-NH(2) (2) binds to hCyp-18 with a low affinity (IC(50) = 850 +/- 220 microM) but a potentially useful selectivity for hCyp-18 relative to hFKBP-12, another abundant PPIase. On the basis of X-ray structures of Gag fragments:hCyp-18 complexes, we generated a series of modified peptides in order to probe the determinants of the interaction and hence to select a peptidic ligand displaying a higher affinity than the capsid domain of Gag. We synthesized a series of heptapeptides to test the energetic contribution of amino acids besides the Gly-Pro moiety. In particular the importance of the histidine residue for the interaction was underscored. We also investigated the influence of N- and C-terminal modifications. Hexapeptides containing either deaminovaline (Dav) in place of the N-terminal valine or substitution of the C-terminal alanine amide with a benzylamide group displayed increased affinities. Combination of both modifications gave the most potent competitor Dav-His-Ala-Gly-Pro-Ile-NHBn (28) which has a higher affinity for hCyp-18 (K(d) = 3 +/- 0.5 microM) than the entire capsid protein (K(d) = 16 +/- 4 microM) and a very low affinity for hFKBP-12. Some of our results strongly suggest that the title compound is not a substrate of hCyp-18 and interacts preferentially in the trans conformation.
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Département D'Ingénierie et D'Etudes des Protéines, CEA/Saclay, Bâtiment 152, 91191 Gif-sur-Yvette, France.
Moutiez
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Charbonnier
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Vaudry
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Ménez
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Quéméneur
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Dugave
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D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D002213:Capsid / Q000737:chemistry*; D015195:Drug Design; D015497:HIV-1 / Q000737:chemistry / Q000187:drug effects*; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000138:chemical synthesis / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
D019380:Anti-HIV Agents; D009842:Oligopeptides; D011994:Recombinant Proteins; D019696:Peptidylprolyl Isomerase