1ZP2

Structure of the Mediator subunit cyclin C

Summary for 1ZP2

• Entry DOI: 10.2210/pdb1zp2/pdb
• Descriptor: RNA polymerase II holoenzyme cyclin-like subunit (1 entity in total)
• Functional Keywords: cyclin repeat domains, transcription-cell cycle complex, transcription/cell cycle
• Biological source: Schizosaccharomyces pombe (fission yeast)
• Cellular location: Nucleus (Probable): O94503
• Total number of polymer chains: 1
• Total formula weight: 27100.28

Authors

Hoeppner, S.,Baumli, S.,Cramer, P. (deposition date: 2005-05-16, release date: 2005-07-19, Last modification date: 2024-02-14)

Primary citation

Hoeppner, S.,Baumli, S.,Cramer, P.
Structure of the Mediator Subunit Cyclin C and its Implications for CDK8 Function.
J.Mol.Biol., 350:833-842, 2005

PubMed Abstract: Cyclin C binds the cyclin-dependent kinases CDK8 and CDK3, which regulate mRNA transcription and the cell cycle, respectively. The crystal structure of cyclin C reveals two canonical five-helix repeats and a specific N-terminal helix. In contrast to other cyclins, the N-terminal helix is short, mobile, and in an exposed position that allows for interactions with proteins other than the CDKs. A model of the CDK8/cyclin C pair reveals two regions in the interface with apparently distinct roles. A conserved region explains promiscuous binding of cyclin C to CDK8 and CDK3, and a non-conserved region may be responsible for discrimination of CDK8 against other CDKs involved in transcription. A conserved and cyclin C-specific surface groove may recruit substrates near the CDK8 active site. Activation of CDKs generally involves phosphorylation of a loop at a threonine residue. In CDK8, this loop is longer and the threonine is absent, suggesting an alternative mechanism of activation that we discuss based on a CDK8-cyclin C model.

PubMed: 15979093
DOI: 10.1016/j.jmb.2005.05.041

Experimental method

X-RAY DIFFRACTION (3 Å)