title: The CDK9 tail determines the reaction pathway of positive transcription elongation factor b.
abstract: CDK9, the kinase of positive transcription elongation factor b (P-TEFb), stimulates transcription elongation by phosphorylating RNA polymerase II and transcription elongation factors. Using kinetic analysis of a human P-TEFb complex consisting of CDK9 and cyclin T, we show that the CDK9 C-terminal tail sequence is important for the catalytic mechanism and imposes an ordered binding of substrates and release of products. Crystallographic analysis of a CDK9/cyclin T complex in which the C-terminal tail partially blocks the ATP binding site reveals a possible reaction intermediate. Biochemical characterization of CDK9 mutants supports a model in which the CDK9 tail cycles through different conformational states. We propose that this mechanism is critical for the pattern of CTD Ser2 phosphorylation on actively transcribed genes.
authors.affiliation: Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne NE2 4HH, UK. sbaumli@gmx.ch
authors.forename: Sonja
authors.initials: S
authors.lastname: Baumli
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Hole
authors.forename: Lan-Zhen
authors.initials: LZ
authors.lastname: Wang
authors.forename: Martin E M
authors.initials: ME
authors.lastname: Noble
authors.forename: Jane A
authors.initials: JA
authors.lastname: Endicott
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D056906:Cyclin T / Q000737:chemistry*; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D004004:Dichlororibofuranosylbenzimidazole / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry; D042925:Positive Transcriptional Elongation Factor B / Q000737:chemistry; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000737:chemistry
chemical_list: C503684:CCNT1 protein, human; D056906:Cyclin T; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D004004:Dichlororibofuranosylbenzimidazole; D042925:Positive Transcriptional Elongation Factor B; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9