Cyclosporine A-resistant human immunodeficiency virus type 1 mutants demonstrate that Gag encodes the functional target of cyclophilin A.
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.
Braaten
D
D
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York 10032, USA.
Aberham
C
C
Franke
E K
EK
Yin
L
L
Phares
W
W
Luban
J
J
D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy*; D000591:Amino Acid Isomerases / Q000494:pharmacology* / Q000627:therapeutic use; D001483:Base Sequence; D002352:Carrier Proteins / Q000494:pharmacology* / Q000627:therapeutic use; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D004351:Drug Resistance; D015683:Gene Products, gag / Q000187:drug effects* / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D019696:Peptidylprolyl Isomerase
D002352:Carrier Proteins; D015683:Gene Products, gag; D016572:Cyclosporine; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase