title: Acetylation of conserved lysines in the catalytic core of cyclin-dependent kinase 9 inhibits kinase activity and regulates transcription.
abstract: Promoter clearance and transcriptional processivity in eukaryotic cells are fundamentally regulated by the phosphorylation of the carboxy-terminal domain of RNA polymerase II (RNAPII). One of the kinases that essentially performs this function is P-TEFb (positive transcription elongation factor b), which is composed of cyclin-dependent kinase 9 (CDK9) associated with members of the cyclin T family. Here we show that cellular GCN5 and P/CAF, members of the GCN5-related N-acetyltransferase family of histone acetyltransferases, regulate CDK9 function by specifically acetylating the catalytic core of the enzyme and, in particular, a lysine that is essential for ATP coordination and the phosphotransfer reaction. Acetylation markedly reduces both the kinase function and transcriptional activity of P-TEFb. In contrast to unmodified CDK9, the acetylated fraction of the enzyme is specifically found in the insoluble nuclear matrix compartment. Acetylated CDK9 associates with the transcriptionally silent human immunodeficiency virus type 1 provirus; upon transcriptional activation, it is replaced by the unmodified form, which is involved in the elongating phase of transcription marked by Ser2-phosphorylated RNAPII. Given the conservation of the CDK9 acetylated residues in the catalytic task of virtually all CDK proteins, we anticipate that this mechanism of regulation might play a broader role in controlling the function of other members of this kinase family.
authors.affiliation: ICGEB Trieste, Molecular Medicine Laboratory, Padriciano, 99, 34012 Trieste, Italy.
authors.forename: Arianna
authors.initials: A
authors.lastname: Sabò
authors.forename: Marina
authors.initials: M
authors.lastname: Lusic
authors.forename: Anna
authors.initials: A
authors.lastname: Cereseto
authors.forename: Mauro
authors.initials: M
authors.lastname: Giacca
mesh_terms: D000107:Acetylation; D000255:Adenosine Triphosphate / Q000378:metabolism; D020134:Catalytic Domain; D002451:Cell Compartmentation; D002460:Cell Line; D056906:Cyclin T; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016213:Cyclins / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D008239:Lysine / Q000737:chemistry / Q000502:physiology; D009000:Monocytes / Q000201:enzymology; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D042925:Positive Transcriptional Elongation Factor B / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D011533:Proviruses / Q000235:genetics*; D012319:RNA Polymerase II / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000502:physiology; D014158:Transcription, Genetic / Q000502:physiology*; D017735:Virus Latency
chemical_list: C503684:CCNT1 protein, human; D056906:Cyclin T; D016213:Cyclins; D004279:DNA, Viral; D011993:Recombinant Fusion Proteins; D010768:Phosphoserine; D000255:Adenosine Triphosphate; D042925:Positive Transcriptional Elongation Factor B; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II; D008239:Lysine