SIRT7-dependent deacetylation of CDK9 activates RNA polymerase II transcription

Blank, Maximilian F.; Chen, Sifan; Poetz, Fabian; Schnölzer, Martina; Voit, Renate; Grummt, Ingrid

Previous studies have shown that acetylation of lysine 48 (K48) compromises CDK9 function (32, 33) . To assay the impact of K48 acetylation on CDK9 activity, we compared wildtype CDK9 with mutants in which K48 has been replaced by glutamine or arginine, thus mimicking the acetylated or deacetylated state of CDK9. In accord with K48 acetylation regulating CDK9 activity, phosphorylation of RPB1 by the acetylation-defective mutant CDK9/K48R was higher than wildtype CDK9, while the acetylationmimicking mutant CDK9/K48Q was enzymatically inactive ( Figure 3G and Supplementary Figure S3G ). Furthermore, phosphorylation of RPB1 was markedly impaired if CDK9 was purified from SIRT7-depleted cells, supporting that hypoacetylation is required for CDK9 activity ( Figure 3H and Supplementary Figure S3H ). The inverse correlation of acetylation and kinase activity of CDK9 reinforces the relevance of SIRT7-dependent deacetylation of K48 for CTD phosphorylation.