title: Cyclin/CDK regulates the nucleocytoplasmic localization of the human papillomavirus E1 DNA helicase.
abstract: Cyclin-dependent kinases (CDKs) play key roles in eukaryotic DNA replication and cell cycle progression. Phosphorylation of components of the preinitiation complex activates replication and prevents reinitiation. One mechanism is mediated by nuclear export of critical proteins. Human papillomavirus (HPV) DNA replication requires cellular machinery in addition to the viral replicative DNA helicase E1 and origin recognition protein E2. E1 phosphorylation by cyclin/CDK is critical for efficient viral DNA replication. We now show that E1 is phosphorylated by CDKs in vivo and that phosphorylation regulates its nucleocytoplasmic localization. We identified a conserved regulatory region for localization which contains a dominant leucine-rich nuclear export sequence (NES), the previously defined cyclin binding motif, three serine residues that are CDK substrates, and a putative bipartite nuclear localization sequence. We show that E1 is exported from the nucleus by a CRM1-dependent mechanism unless the NES is inactivated by CDK phosphorylation. Replication activities of E1 phosphorylation site mutations are reduced and correlate inversely with their increased cytoplasmic localization. Nuclear localization and replication activities of most of these mutations are enhanced or restored by mutations in the NES. Collectively, our data demonstrate that CDK phosphorylation controls E1 nuclear localization to support viral DNA amplification. Thus, HPV adopts and adapts the cellular regulatory mechanism to complete its reproductive program.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, 510 McCallum Basic Health Sciences Building, 1918 University Blvd., Birmingham, AL 35294-0005, USA.
authors.forename: Wentao
authors.initials: W
authors.lastname: Deng
authors.forename: Biing Yuan
authors.initials: BY
authors.lastname: Lin
authors.forename: Ge
authors.initials: G
authors.lastname: Jin
authors.forename: Crystal G
authors.initials: CG
authors.lastname: Wheeler
authors.forename: Tianlin
authors.initials: T
authors.lastname: Ma
authors.forename: J Wade
authors.initials: JW
authors.lastname: Harper
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Broker
authors.forename: Louise T
authors.initials: LT
authors.lastname: Chow
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D006801:Humans; D028884:Karyopherins / Q000378:metabolism; D027383:Papillomaviridae / Q000472:pathogenicity*; D010766:Phosphorylation; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication; D000097606:Exportin 1 Protein
chemical_list: D018844:Cyclin-Dependent Kinases; D004265:DNA Helicases; D004268:DNA-Binding Proteins; D028884:Karyopherins; D018160:Receptors, Cytoplasmic and Nuclear; D014764:Viral Proteins; D000097606:Exportin 1 Protein; C084304:E1 protein, Human papillomavirus type 11