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J. Virol., 08 1996, 5170-5176, Vol 70, No. 8
D Braaten, C Aberham, EK Franke, L Yin, W Phares and J Luban
The cellular peptidyl-prolyl isomerase cyclophilin A is incorporated into
human immunodeficiency virus type 1 virions via contacts with the
proline-rich domain of the Gag polyprotein. Cyclosporine A and
nonimmunosuppressive analogs bind with high affinity to cyclophilin A,
compete with Gag for binding to cyclophilin A, and prevent incorporation of
cyclophilin A into virions; in parallel with the disruption of cyclophilin
A incorporation into virions, there is a linear reduction in the initiation
of reverse transcription after infection of a T cell. Passage of human
immunodeficiency virus type 1 in the presence of the drug selects one of
two mutations, either of which alters the proline-rich domain of Gag and is
sufficient to confer drug resistance on the cloned wild-type provirus.
Neither mutation alters Gag's cyclophilin A-binding properties in vitro,
and cyclophilin A incorporation into drug-resistant virions is effectively
disrupted by cyclosporine A, indicating that the drug-resistant mutants do
not require virion-associated cyclophilin A to initiate infection. That
Gag's functional dependence on cyclophilin A can be differentiated
genetically from its ability to bind cyclophilin A is further demonstrated
by the rescue of a mutation precluding cyclophilin A packaging by a
mutation conferring cyclosporine A resistance. These experiments
demonstrate that, in addition to its ability to package cyclophilin A into
virions, gag encodes the functional target of cyclophilin A.
Copyright © 1996, American Society for Microbiology
Cyclosporine A-resistant human immunodeficiency virus type 1 mutants demonstrate that Gag encodes the functional target of cyclophilin A
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York 10032, USA.
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