Structural highlights
FunctionCTK3_SCHPO Subunit of the CTDK-I complex, which hyperphosphorylates the C-terminal heptapeptide repeat domain (CTD) of the largest RNA polymerase II subunit. As part of the CTDK-I complex, involved in RNA polymerase II transcriptional elongation and pre-mRNA 3'-end processing. Together with ctk2, required for ctk1/lsk1 CTD kinase activation (By similarity). Publication Abstract from PubMedCTDK-I is a yeast kinase complex that phosphorylates the C-terminal repeat domain (CTD) of RNA polymerase II (Pol II) to promote transcription elongation. CTDK-I contains the cyclin-dependent kinase Ctk1 (homologous to human CDK9/CDK12), the cyclin Ctk2 (human cyclin K), and the yeast-specific subunit Ctk3, which is required for CTDK-I stability and activity. Here we predict that Ctk3 consists of a N-terminal CTD-interacting domain (CID) and a C-terminal three-helix bundle domain. We determine the X-ray crystal structure of the N-terminal domain of the Ctk3 homologue Lsg1 from the fission yeast Schizosaccharomyces pombe at 2.0 A resolution. The structure reveals eight helices arranged into a right-handed superhelical fold that resembles the CID domain present in transcription termination factors Pcf11, Nrd1, and Rtt103. Ctk3 however shows different surface properties and no binding to CTD peptides. Together with the known structure of Ctk1 and Ctk2 homologues, our results lead to a molecular framework for analyzing the structure and function of the CTDK-I complex. This article is protected by copyright. All rights reserved. Structure of Ctk3, a subunit of the RNA polymerase II CTD kinase complex, reveals a non-canonical CTD-interacting domain fold.,Muhlbacher W, Mayer A, Sun M, Remmert M, Cheung AC, Niesser J, Soeding J, Cramer P Proteins. 2015 Jul 28. doi: 10.1002/prot.24869. PMID:26219431[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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