title: The cyclin-dependent kinase ortholog pUL97 of human cytomegalovirus interacts with cyclins.
abstract: The human cytomegalovirus (HCMV)-encoded protein kinase, pUL97, is considered a cyclin-dependent kinase (CDK) ortholog, due to shared structural and functional characteristics. The primary mechanism of CDK activation is binding to corresponding cyclins, including cyclin T1, which is the usual regulatory cofactor of CDK9. This study provides evidence of direct interaction between pUL97 and cyclin T1 using yeast two-hybrid and co-immunoprecipitation analyses. Confocal immunofluorescence revealed partial colocalization of pUL97 with cyclin T1 in subnuclear compartments, most pronounced in viral replication centres. The distribution patterns of pUL97 and cyclin T1 were independent of HCMV strain and host cell type. The sequence domain of pUL97 responsible for the interaction with cyclin T1 was between amino acids 231-280. Additional co-immunoprecipitation analyses showed cyclin B1 and cyclin A as further pUL97 interaction partners. Investigation of the pUL97-cyclin T1 interaction in an ATP consumption assay strongly suggested phosphorylation of pUL97 by the CDK9/cyclin T1 complex in a substrate concentration-dependent manner. This is the first demonstration of interaction between a herpesviral CDK ortholog and cellular cyclins.
authors.forename: Laura
authors.initials: L
authors.lastname: Graf
authors.forename: Rike
authors.initials: R
authors.lastname: Webel
authors.forename: Sabrina
authors.initials: S
authors.lastname: Wagner
authors.forename: Stuart T
authors.initials: ST
authors.lastname: Hamilton
authors.forename: William D
authors.initials: WD
authors.lastname: Rawlinson
authors.forename: Heinrich
authors.initials: H
authors.lastname: Sticht
authors.affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany. manfred.marschall@viro.med.uni-erlangen.de.
authors.forename: Manfred
authors.initials: M
authors.lastname: Marschall
mesh_terms: D002460:Cell Line; D019925:Cyclin A / Q000378:metabolism; D056744:Cyclin B1 / Q000378:metabolism; D056906:Cyclin T / Q000378:metabolism*; D003587:Cytomegalovirus / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D020798:Two-Hybrid System Techniques
chemical_list: C534699:CCNB1 protein, human; C503684:CCNT1 protein, human; D019925:Cyclin A; D056744:Cyclin B1; D056906:Cyclin T; D017853:Phosphotransferases (Alcohol Group Acceptor); C075365:ganciclovir kinase