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Viral protein R regulates nuclear import of the HIV‐1 pre‐integration complex
Author(s) -
Popov Serguei,
Rexach Michael,
Zybarth Gabriele,
Reiling Norbert,
Lee MayAnn,
Ratner Lee,
Lane Cynthia M.,
Moore Mary Shan,
Blobel Günter,
Bukrinsky Michael
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.4.909
Subject(s) - karyopherin , nuclear transport , biology , nuclear localization sequence , microbiology and biotechnology , viral replication , mutant , importin , nuclear export signal , virology , cell nucleus , virus , biochemistry , nucleus , gene
Replication of human immunodeficiency virus type 1 (HIV‐1) in non‐dividing cells critically depends on import of the viral pre‐integration complex into the nucleus. Genetic evidence suggests that viral protein R (Vpr) and matrix antigen (MA) are directly involved in the import process. An in vitro assay that reconstitutes nuclear import of HIV‐1 pre‐integration complexes in digitonin‐permeabilized cells was used to demonstrate that Vpr is the key regulator of the viral nuclear import process. Mutant HIV‐1 pre‐integration complexes that lack Vpr failed to be imported in vitro , whereas mutants that lack a functional MA nuclear localization sequence (NLS) were only partially defective. Strikingly, the import defect of the Vpr − mutant was rescued when recombinant Vpr was re‐added. In addition, import of Vpr − virus was rescued by adding the cytosol of HeLa cells, where HIV‐1 replication had been shown to be Vpr‐independent. In a solution binding assay, Vpr associated with karyopherin α, a cellular receptor for NLSs. This association increased the affinity of karyopherin α for basic‐type NLSs, including that of MA, thus explaining the positive effect of Vpr on nuclear import of the HIV‐1 pre‐integration complex and BSA–NLS conjugates. These results identify the biochemical mechanism of Vpr function in transport of the viral pre‐integration complex to, and across, the nuclear membrane.