Characterization of the Nuclear Import Pathway for HIV-1 Integrase

• Published in: The Journal of biological chemistry Vol. 276; no. 21; pp. 18102 - 18107
• Main Authors: Depienne, Christel, Mousnier, Aurélie, Leh, Hervé, Le Rouzic, Erwann, Dormont, Dominique, Benichou, Serge, Dargemont, Catherine
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25.05.2001; American Society for Biochemistry and Molecular Biology
• Subjects: Biological Transport; Cell Nucleus - metabolism; HeLa Cells; HIV Infections - virology; HIV Integrase - metabolism; HIV-1 - physiology; Human immunodeficiency virus 1; Humans; karyopherin; karyopherins; pre-integration complex; Ran protein; Virus Replication
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M009029200

The karyophilic properties of the human immunodeficiency virus, type I (HIV-1) pre-integration complex (PIC) allow the virus to infect non-dividing cells. To better understand the mechanisms responsible for nuclear translocation of the PIC, we investigated nuclear import of HIV-1 integrase (IN), a PIC-associated viral enzyme involved in the integration of the viral genome in the host cell DNA. Accumulation of HIV-1 IN into nuclei of digitonin-permeabilized cells does not result from passive diffusion but rather from an active transport that occurs through the nuclear pore complexes. HIV-1 IN is imported by a saturable mechanism, implying that a limiting cellular factor is responsible for this process. Although IN has been previously proposed to contain classical basic nuclear localization signals, we found that nuclear accumulation of IN does not involve karyopherins α, β1, and β2-mediated pathways. Neither the non-hydrolyzable GTP analog, guanosine 5′-O-(thiotriphosphate), nor the GTP hydrolysis-deficient Ran mutant, RanQ69L, significantly affects nuclear import of IN, which depends instead on ATP hydrolysis. Therefore these results support the idea that IN import is not mediated by members of the karyopherin β family. More generally, in vitro nuclear import of IN does not require addition of cytosolic factors, suggesting that cellular factor(s) involved in this active but atypical pathway process probably remain associated with the nuclear compartment or the nuclear pore complexes from permeabilized cells.