AEGiS-05CROI: Vpr is the key regulator of HIV-1 nuclear import.

5th Conference on Retroviruses and Opportunistic Infections


Chicago, IL - February 1-5, 1998



Vpr is the key regulator of HIV-1 nuclear import.

Conf Retroviruses Opportunistic Infect 1998 Feb 1-5; 5th:84 (abstract no. 29)

Bukrinsky M, Popov S, Zybarth G; Picower Institute for Medical Research, Manhasset, NY.

Replication of HIV-1 in non-dividing cells depends on active import of the viral pre-integration complex into the cell nucleus. Several viral proteins including Vpr, matrix antigen (MA), and integrase (IN) have been implicated in this process, resulting in conflicting reports and confusion regarding the role of each determinant. Here we developed an in vitro model which allows investigation of HIV-1 nuclear import independently of other events, such as entry and uncoating, that normally accompany viral infection. Using this model, we demonstrate that Vpr mutation completely inactivated nuclear import, while mutation of the MA nuclear localization signal (NLS) had only a partial effect. Strikingly, the import of Vpr-defective virus was restored when Vpr was added back as a recombinant protein. Using a solution binding assay, we demonstrate that Vpr binds to karyopherin alpha, a cellular receptor for NLSs. However, Vpr binding was NLS-independent and could not be competed by NLS-peptide. Surprisingly, NLS-dependent binding of MA to karyopherin alpha could not be competed by NLS peptide when Vpr was bound to karyopherin alpha, indicating that Vpr enhances affnity of karyopherin alpha for NLSs. This was demonstrated directly in binding experiments where Vpr increased affnity of karyopherin alpha-MA NLS interaction about 10-fold. At low concentrations, Vpr also stimulated nuclear import of an artificial weak karyophile, without affecting import of a strong karyophile. Surprisingly, at high concentrations, Vpr potently inhibited nuclear import. Our results suggest a new model of HIV-1 nuclear import, in which Vpr plays a key role by increasing the karyophilic potential of the HIV-1 pre-integration complex which by itself is a weak karyophile. The details of this model will be presented.

Keywords: AEGIS, HIV-1, Active Transport, Cell Nucleus, Nuclear Localization Signal, Virus Replication, Cell Nucleus, HIV-1 Reverse Transcriptase, Integrase, Defective Viruses, Carrier Proteins, alpha Karyopherins, Mutation, In Vitro, genetics, virology, AIDSKWDaegis,hiv-1,activetransport,cellnucleus,nuclearlocalizationsignal,virusreplication,cellnucleus,hiv-1reversetranscriptase,integrase,defectiveviruses,carrierproteins,alphakaryopherins,mutation,invitro,genetics,virology,aids

1998-02-01
29

Copyright © 1998 - Foundation for Retrovirology and Human Health (IAS). Reproduction of this abstract (other than one copy for personal reference) must be cleared through the Foundation for Retrovirology and Human Health. Licensed from National Library of Medicine.