title: Interactions of Cdk7 and Kin28 with Hint/PKCI-1 and Hnt1 histidine triad proteins.
abstract: Cyclin-dependent kinase 7 (Cdk7) forms a trimeric complex with cyclin H and Mat1 to form the mammalian Cdk-activating kinase, CAK, as well as a part of the basal transcription factor TFIIH, where Cdk7 phosphorylates the C-terminal domain (CTD) of the large subunit of RNA polymerase II. Here, we report a novel interaction between Cdk7 and a histidine triad (HIT) family protein, Hint/PKCI-1. This interaction was initially observed in a yeast two-hybrid study and subsequently verified by co-immunoprecipitation and subcellular localization studies, where overexpression of Cdk7 leads to partial relocalization of Hint to the nucleus. The physical association is independent of cyclin H binding or Cdk7 kinase activity and is conserved between the related Sacharomyces cerevisiae CTD kinase Kin28 and the HIT protein Hnt1. Furthermore, combination of a disruption of HNT1 and a KIN28 temperature-sensitive allele in S. cerevisiae led to highly elongated cell morphology and reduced colony formation, indicating a genetic interaction between KIN28 and HNT1. The physical and genetic interactions of Hint and Hnt1 with Cdk7 and Kin28 suggest a role for this class of histidine triad proteins in the regulation of Cdk7 and Kin28 functions.
authors.affiliation: Haartman Institute & Biocentrum Helsinki, P. O. Box 21, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: N
authors.initials: N
authors.lastname: Korsisaari
authors.forename: T P
authors.initials: TP
authors.lastname: Mäkelä
mesh_terms: D000483:Alleles; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D056748:Cyclin H; D018844:Cyclin-Dependent Kinases; D016213:Cyclins / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005982:Glutathione Transferase / Q000378:metabolism; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D016296:Mutagenesis; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D000095043:Cyclin-Dependent Kinase-Activating Kinase
chemical_list: C534751:CCNH protein, human; D056748:Cyclin H; D016213:Cyclins; C405403:Hinterteil protein, Hydra vulgaris; D029701:Saccharomyces cerevisiae Proteins; D006639:Histidine; D005982:Glutathione Transferase; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; C084210:Kin28 protein kinase, S cerevisiae; D000095043:Cyclin-Dependent Kinase-Activating Kinase