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Nonradioactive Assay to Measure Polynucleotide Phosphorylation of Small Nucleotide Substrates
Published on: May 8, 2020
Structure and activation mechanism of the yeast RNA Pol II CTD kinase CTDK-1 complex
Yihu Xie1, Christopher L Lord2, Bradley P Clarke1
1Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232.
Abstract:
The C-terminal domain (CTD) kinase I (CTDK-1) complex is the primary RNA Polymerase II (Pol II) CTD Ser2 kinase in budding yeast. CTDK-1 consists of a cyclin-dependent kinase (CDK) Ctk1, a cyclin Ctk2, and a unique subunit Ctk3 required for CTDK-1 activity. Here, we present a crystal structure of CTDK-1 at 1.85-Å resolution. The structure reveals that, compared to the canonical two-component CDK-cyclin system, the third component Ctk3 of CTDK-1 plays a critical role in Ctk1 activation by stabilizing a key element of CDK regulation, the T-loop, in an active conformation. In addition, Ctk3 contributes to the assembly of CTDK-1 through extensive interactions with both Ctk1 and Ctk2. We also demonstrate that CTDK-1 physically and genetically interacts with the serine/arginine-like protein Gbp2. Together, the data in our work reveal a regulatory mechanism of CDK complexes.
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