title: N-terminal half of transportin SR2 interacts with HIV integrase.
abstract: The karyopherin transportin SR2 (TRN-SR2, TNPO3) is responsible for shuttling specific cargoes such as serine/arginine-rich splicing factors from the cytoplasm to the nucleus. This protein plays a key role in HIV infection by facilitating the nuclear import of the pre-integration complex (PIC) that contains the viral DNA as well as several cellular and HIV proteins, including the integrase. The process of nuclear import is considered to be the bottleneck of the viral replication cycle and therefore represents a promising target for anti-HIV drug design. Previous studies have demonstrated that the direct interaction between TRN-SR2 and HIV integrase predominantly involves the catalytic core domain (CCD) and the C-terminal domain (CTD) of the integrase. We aimed at providing a detailed molecular view of this interaction through a biochemical characterization of the respective protein complex. Size-exclusion chromatography was used to characterize the interaction of TRN-SR2 with a truncated variant of the HIV-1 integrase, including both the CCD and CTD. These experiments indicate that one TRN-SR2 molecule can specifically bind one CCD-CTD dimer. Next, the regions of the solenoid-like TRN-SR2 molecule that are involved in the interaction with integrase were identified using AlphaScreen binding assays, revealing that the integrase interacts with the N-terminal half of TRN-SR2 principally through the HEAT repeats 4, 10, and 11. Combining these results with small-angle X-ray scattering data for the complex of TRN-SR2 with truncated integrase, we propose a molecular model of the complex. We speculate that nuclear import of the PIC may proceed concurrently with the normal nuclear transport.
authors.affiliation: From the Laboratory for Biocrystallography and.
authors.forename: Vicky G
authors.identifier: 0000-0002-6452-1871
authors.initials: VG
authors.lastname: Tsirkone
authors.affiliation: the Laboratory for Molecular Virology and Gene Therapy, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Jolien
authors.initials: J
authors.lastname: Blokken
authors.affiliation: the Laboratory for Molecular Virology and Gene Therapy, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Flore
authors.initials: F
authors.lastname: De Wit
authors.affiliation: From the Laboratory for Biocrystallography and.
authors.forename: Jolien
authors.initials: J
authors.lastname: Breemans
authors.affiliation: the Laboratory for Molecular Virology and Gene Therapy, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: De Houwer
authors.affiliation: the Laboratory for Molecular Virology and Gene Therapy, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Zeger
authors.identifier: 0000-0002-3982-1565
authors.initials: Z
authors.lastname: Debyser
authors.affiliation: the Laboratory for Molecular Virology and Gene Therapy, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Frauke
authors.initials: F
authors.lastname: Christ
authors.affiliation: From the Laboratory for Biocrystallography and sergei.strelkov@kuleuven.be.
authors.forename: Sergei V
authors.identifier: 0000-0001-7189-4652
authors.initials: SV
authors.lastname: Strelkov
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000235:genetics; D019380:Anti-HIV Agents / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015195:Drug Design; D015658:HIV Infections; D019427:HIV Integrase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015497:HIV-1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D000072417:Protein Domains; D020449:Repetitive Sequences, Amino Acid; D014961:X-Ray Diffraction; D028961:beta Karyopherins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D019380:Anti-HIV Agents; C546476:TNPO3 protein, human; D028961:beta Karyopherins; D019427:HIV Integrase
keywords: host-pathogen interaction; human immunodeficiency virus (HIV); integrase; nuclear transport; protein-protein interaction; small-angle X-ray scattering (SAXS); transportin SR2