Previous Article | Next Article ![]()
J. Virol., Mar 1997, 2107-2113, Vol 71, No. 3
D Braaten, H Ansari and J Luban
Completion of an early step in the human immunodeficiency virus type 1
(HIV-1) life cycle requires incorporation into virions of the cellular
peptidyl-prolyl isomerase cyclophilin A (CyPA) by the Gag polyprotein.
Elucidation of the biochemical role of CyPA would be aided by a detailed
analysis of the genetic requirements for the formation of the Gag-CyPA
complex; previous experiments have demonstrated the requirement for a
critical proline and the immediately preceding glycine, located within the
capsid domain of Gag, but nothing is known about the necessary CyPA
residues. Cyclophilins possess a hydrophobic pocket where
proline-containing peptide substrates and the immunosuppressive drug
cyclosporine A bind. In this study, we engineered five CyPA mutations, each
of which alters a residue that contributes to the hydrophobic pocket.
Compared with the wild-type protein, all of the mutants drastically reduced
CyPA binding to HIV-1 Gag and similarly inhibited CyPA incorporation into
virions. In addition, we demonstrated that previously reported differences
between the Gag-binding properties of CyPA and CyPB are due to adventitious
association involving residues in the signal sequence of CyPB and that the
core domain of CyPB interacts with Gag in a fashion which is
indistinguishable from that of CyPA. These studies indicate that, as with
other proline-containing peptides or cyclosporine A, HIV-1 Gag directly
contacts residues in the hydrophobic pocket of CyPA.
Copyright © 1997, American Society for Microbiology
The hydrophobic pocket of cyclophilin is the binding site for the human immunodeficiency virus type 1 Gag polyprotein
Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
This article has been cited by other articles:
| J. Bacteriol. | Mol. Cell. Biol. | Microbiol. Mol. Biol. Rev. |
|---|
| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
|---|