LEDGF/p75 is essential for nuclear and chromosomal targeting of HIV-1 integrase in human cells.
We have reported that human immunodeficiency virus type 1 (HIV-1) integrase (IN) forms a specific nuclear complex with human lens epithelium-derived growth factor/transcription co-activator p75 (LEDGF/p75) protein. We now studied the IN-LEDGF/p75 interaction and nuclear import of IN in living cells using fusions of IN and LEDGF/p75 with enhanced green fluorescent protein and far-red fluorescent protein HcRed1. We show that both the N-terminal zinc binding domain and the central core domains of IN are involved in the interaction with LEDGF/p75. Both domains are essential for nuclear localization of IN as well as for the association of IN with condensed chromosomes during mitosis. However, upon overexpression of LEDGF/p75, the core domain fragment of IN was recruited to the nuclei and mitotic chromosomes with a distribution pattern characteristic of the full-length protein, indicating that it harbors the main determinant for interaction with LEDGF/p75. Although the C-terminal domain of IN was dispensable for nuclear/chromosomal localization, a fusion of the C-terminal IN fragment with enhanced green fluorescent protein was found exclusively in the nucleus, with a diffuse nuclear/nucleolar distribution, suggesting that the C-terminal domain may also play a role in the nuclear import of IN. In contrast to LEDGF/p75, its alternative splice variant, p52, did not interact with HIV-1 IN in vitro and in living cells. Finally, RNA interference-mediated knock-down of endogenous LEDGF/p75 expression abolished nuclear/chromosomal localization of IN. We conclude, therefore, that the interaction with LEDGF/p75 accounts for the karyophilic properties and chromosomal targeting of HIV-1 IN.
Maertens
Goedele
G
Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
Cherepanov
Peter
P
Pluymers
Wim
W
Busschots
Katrien
K
De Clercq
Erik
E
Debyser
Zeger
Z
Engelborghs
Yves
Y
D021581:Active Transport, Cell Nucleus; D017398:Alternative Splicing; D001483:Base Sequence; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D019427:HIV Integrase / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D015032:Zinc / Q000737:chemistry
D036341:Intercellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; C119380:lens epithelium-derived growth factor; D019427:HIV Integrase; D015032:Zinc