Research

Inhibition of HIV-1 integrase nuclear import and replication by a peptide bearing integrase putative nuclear localization signal

Aviad Levin^1†, Ayelet Armon-Omer^4,1†, Joseph Rosenbluh¹, Naomi Melamed-Book¹, Adolf Graessmann², Elisabeth Waigmann³ and Abraham Loyter^1*

• * Corresponding author: Abraham Loyter loyter@cc.huji.ac.il

• † Equal contributors

Author Affiliations

¹ Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

² Institut fur Molekularbiologie und Biochemie, Free University of Berlin, Germany

³ Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Institute of Medical Biochemistry, Medical University of Vienna, Austria

⁴ Ziv Medical Center, Zefat 13100, Israel

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Retrovirology 2009, 6:112 doi:10.1186/1742-4690-6-112

Published: 5 December 2009

Abstract

Background

The integrase (IN) of human immunodeficiency virus type 1 (HIV-1) has been implicated in different steps during viral replication, including nuclear import of the viral pre-integration complex. The exact mechanisms underlying the nuclear import of IN and especially the question of whether it bears a functional nuclear localization signal (NLS) remain controversial.

Results

Here, we studied the nuclear import pathway of IN by using multiple in vivo and in vitro systems. Nuclear import was not observed in an importin α temperature-sensitive yeast mutant, indicating an importin α-mediated process. Direct interaction between the full-length IN and importin α was demonstrated in vivo using bimolecular fluorescence complementation assay (BiFC). Nuclear import studies in yeast cells, with permeabilized mammalian cells, or microinjected cultured mammalian cells strongly suggest that the IN bears a NLS domain located between residues 161 and 173. A peptide bearing this sequence -NLS-IN peptide- inhibited nuclear accumulation of IN in transfected cell-cycle arrested cells. Integration of viral cDNA as well as HIV-1 replication in viral cell-cycle arrested infected cells were blocked by the NLS-IN peptide.

Conclusion

Our present findings support the view that nuclear import of IN occurs via the importin α pathway and is promoted by a specific NLS domain. This import could be blocked by NLS-IN peptide, resulting in inhibition of viral infection, confirming the view that nuclear import of the viral pre-integration complex is mediated by viral IN.