title: Phosphorylation by MAPK regulates simian immunodeficiency virus Vpx protein nuclear import and virus infectivity.
abstract: Transport of the viral genome into the nucleus required phosphorylation of components in the preintegration complex by virion-associated host cellular kinases. In this study, we showed that ERK-2/MAPK is associated with simian immunodeficiency virus (SIV) virions and regulated the nuclear transport of Vpx and virus replication in non-proliferating target cells by phosphorylating Vpx. Suppression of the virion-associated ERK-2 activity by MAPK pathway inhibitors impaired both Vpx nuclear import and viral infectivity without affecting virus particle maturation and release. In addition, mutation analysis indicated that the inactivation of Vpx phosphorylation precluded nuclear import and reduced virus replication in macrophage cultures, even when functional integrase and Gag matrix proteins implicated in viral preintegration complex nuclear import are present. In this study, we also showed that co-localization of Vpx with Gag precursor in the cytoplasm is a prerequisite for Vpx incorporation into virus particles. Substitution of hydrophobic Leu-74 and Ile-75 with serines in the helical domain abrogated Vpx nuclear import, and its incorporation into virus particles, despite its localization in the cytoplasm, suggested that the structural integrity of helical domains is critical for Vpx functions. Taken together, these studies demonstrated that the host cell MAPK signal transduction pathway regulated an early step in SIV infection.
authors.affiliation: Laboratory of Molecular Virology, Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Hyderabad 500 076, India.
authors.forename: Palakurthy
authors.initials: P
authors.lastname: Rajendra Kumar
authors.forename: Prabhat K
authors.initials: PK
authors.lastname: Singhal
authors.forename: Malireddi R K
authors.initials: MR
authors.lastname: Subba Rao
authors.forename: Sundarasamy
authors.initials: S
authors.lastname: Mahalingam
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D004252:DNA Mutational Analysis; D015683:Gene Products, gag / Q000378:metabolism; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D007532:Isoleucine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D020935:MAP Kinase Signaling System; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D015302:Simian Immunodeficiency Virus / Q000378:metabolism / Q000472:pathogenicity*; D013997:Time Factors; D014162:Transfection; D014709:Vero Cells; D054334:Viral Regulatory and Accessory Proteins / Q000378:metabolism*
chemical_list: D015683:Gene Products, gag; D011993:Recombinant Fusion Proteins; C513059:VPX protein, Simian immunodeficiency virus; D054334:Viral Regulatory and Accessory Proteins; D007532:Isoleucine; D012694:Serine; D005982:Glutathione Transferase; D019950:Mitogen-Activated Protein Kinase 1; D007930:Leucine