Research

Mutations affecting interaction of integrase with TNPO3 do not prevent HIV-1 cDNA nuclear import

Alexandra Cribier^1,2,3, Emmanuel Ségéral^1,2,3, Olivier Delelis⁴, Vincent Parissi⁵, Aurélie Simon^1,2,3, Marc Ruff⁶, Richard Benarous⁷ and Stéphane Emiliani^1,2,3*

• * Corresponding author: Stéphane Emiliani stephane.emiliani@inserm.fr

Author Affiliations

¹ Inserm, U1016, Institut Cochin, Paris, France

² CNRS, UMR 8104, Paris, France

³ Université Paris Descartes, Paris, France

⁴ LBPA, CNRS, ENS de Cachan, Cachan, France

⁵ Laboratoire MFP, UMR 5234-CNRS, Université de Bordeaux Victor Segalen, Bordeaux, France

⁶ IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Département de Biologie et de Génomique Structurales, UDS, CNRS, INSERM, Illkirch, France

⁷ Mutabilis (S.A.), Romainville, France

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Retrovirology 2011, 8:104 doi:10.1186/1742-4690-8-104

Published: 16 December 2011

Abstract

Background

Integration of human immunodeficiency virus type 1 (HIV-1) into a host cell chromosome is an essential step under the control of the viral integrase (IN). Although this enzyme is necessary and sufficient to catalyze the integration reaction in vitro, cellular cofactors are involved in the process in vivo. The chromatin-associated factor LEDGF/p75 interacts with IN and promotes integration to transcription units of the host genome. HIV-1 IN also binds the karyopherin TNPO3, however the significance of this interaction during viral replication remains to be explored.

Results

Here we present a functional analysis of IN mutants impaired for LEDGF/p75 and TNPO3 interaction. Among them, IN W131A and IN Q168L, that were previously identified to be deficient for LEDGF/p75 interaction, were also partially impaired for TNPO3 binding. We observed that mutations abolishing IN ability to form tetramers resulted in a severe reduction in LEDGF/p75 binding. In sharp contrast, no correlation could be found between the ability of IN to multimerize and TNPO3 interaction. Most of the mutant viruses were essentially impaired for the integration step whereas the amount of 2-LTR circles, reflecting the nuclear import of the viral DNA, was not significantly affected.

Conclusion

Our functional analysis of HIV-1 IN mutants reveals distinct structural basis for TNPO3 interaction and suggests that the interaction between IN and TNPO3 is not a major determinant of nuclear import but could take place at a nuclear step prior to integration.