title: Nuclear targeting of protein phosphatase-1 by HIV-1 Tat protein.
abstract: Transcription of human immunodeficiency virus (HIV)-1 genes is activated by HIV-1 Tat protein, which induces phosphorylation of the C-terminal domain of RNA polymerase-II by CDK9/cyclin T1. We previously showed that Tat-induced HIV-1 transcription is regulated by protein phosphatase-1 (PP1). In the present study we demonstrate that Tat interacts with PP1 and that disruption of this interaction prevents induction of HIV-1 transcription. We show that PP1 interacts with Tat in part through the binding of Val36 and Phe38 of Tat to PP1 and that Tat is involved in the nuclear and subnuclear targeting of PP1. The PP1 binding mutant Tat-V36A/F38A displayed a decreased affinity for PP1 and was a poor activator of HIV-1 transcription. Surprisingly, Tat-Q35R mutant that had a higher affinity for PP1 was also a poor activator of HIV-1 transcription, because strong PP1 binding competed out binding of Tat to CDK9/cyclin T1. Our results suggest that Tat might function as a nuclear regulator of PP1 and that interaction of Tat with PP1 is critical for activation of HIV-1 transcription by Tat.
authors.affiliation: Center for Sickle Cell Disease, Howard University, Washington, DC 20059, USA.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Ammosova
authors.forename: Marina
authors.initials: M
authors.lastname: Jerebtsova
authors.forename: Monique
authors.initials: M
authors.lastname: Beullens
authors.forename: Bart
authors.initials: B
authors.lastname: Lesage
authors.forename: Angela
authors.initials: A
authors.lastname: Jackson
authors.forename: Fatah
authors.initials: F
authors.lastname: Kashanchi
authors.forename: William
authors.initials: W
authors.lastname: Southerland
authors.forename: Victor R
authors.initials: VR
authors.lastname: Gordeuk
authors.forename: Mathieu
authors.initials: M
authors.lastname: Bollen
authors.forename: Sergei
authors.initials: S
authors.lastname: Nekhai
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019921:Biotinylation; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015696:Gene Products, tat / Q000378:metabolism / Q000502:physiology*; D015756:Genes, tat / Q000235:genetics; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010762:Phosphorylase a / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D054645:Protein Phosphatase 1; D012319:RNA Polymerase II / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014633:Valine / Q000737:chemistry; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D015696:Gene Products, tat; D019938:Cyclin D1; D010649:Phenylalanine; D010762:Phosphorylase a; D005982:Glutathione Transferase; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D001616:beta-Galactosidase; D014633:Valine