Inhibition of HIV-1 integrase nuclear import and replication by a peptide bearing integrase putative nuclear localization signal.
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 alpha temperature-sensitive yeast mutant, indicating an importin alpha-mediated process. Direct interaction between the full-length IN and importin alpha 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.


CONCLUSIONS
Our present findings support the view that nuclear import of IN occurs via the importin alpha 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.
Levin
Aviad
A
Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. aviadl@gmail.com
Armon-Omer
Ayelet
A
Rosenbluh
Joseph
J
Melamed-Book
Naomi
N
Graessmann
Adolf
A
Waigmann
Elisabeth
E
Loyter
Abraham
A
D021581:Active Transport, Cell Nucleus / Q000187:drug effects*; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D015658:HIV Infections / Q000378:metabolism / Q000821:virology*; D019427:HIV Integrase / Q000737:chemistry / Q000378:metabolism*; D019428:HIV Integrase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects / Q000502:physiology*; D006367:HeLa Cells; D054884:Host-Pathogen Interactions / Q000187:drug effects; D006801:Humans; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D019913:Nuclear Localization Signals / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology; D016662:Virus Integration / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects*; D028901:alpha Karyopherins / Q000378:metabolism
D019428:HIV Integrase Inhibitors; D019913:Nuclear Localization Signals; D028901:alpha Karyopherins; D019427:HIV Integrase