2I53

Crystal structure of Cyclin K

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.218 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 

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This is version 1.2 of the entry. See complete history. 


Literature

Crystal Structure of Human Cyclin K, a Positive Regulator of Cyclin-dependent Kinase 9.

Baek, K., Brown, R.S., Birrane, G., Ladias, J.A.

(2007) J Mol Biol 366: 563-573

  • DOI: 10.1016/j.jmb.2006.11.057
  • Primary Citation of Related Structures:  
    2I53

  • PubMed Abstract: 

    • Cyclin K and the closely related cyclins T1, T2a, and T2b interact with cyclin-dependent kinase 9 (CDK9) forming multiple nuclear complexes, referred to collectively as positive transcription elongation factor b (P-TEFb). Through phosphorylation of the C-terminal domain of the RNA polymerase II largest subunit, distinct P-TEFb species regulate the transcriptional elongation of specific genes that play central roles in human physiology and disease development, including cardiac hypertrophy and human immunodeficiency virus-1 pathogenesis ...

    Cyclin K and the closely related cyclins T1, T2a, and T2b interact with cyclin-dependent kinase 9 (CDK9) forming multiple nuclear complexes, referred to collectively as positive transcription elongation factor b (P-TEFb). Through phosphorylation of the C-terminal domain of the RNA polymerase II largest subunit, distinct P-TEFb species regulate the transcriptional elongation of specific genes that play central roles in human physiology and disease development, including cardiac hypertrophy and human immunodeficiency virus-1 pathogenesis. We have determined the crystal structure of human cyclin K (residues 11-267) at 1.5 A resolution, which represents the first atomic structure of a P-TEFb subunit. The cyclin K fold comprises two typical cyclin boxes with two short helices preceding the N-terminal box. A prominent feature of cyclin K is an additional helix (H4a) in the first cyclin box that obstructs the binding pocket for the cell-cycle inhibitor p27(Kip1). Modeling of CDK9 bound to cyclin K provides insights into the structural determinants underlying the formation and regulation of this complex. A homology model of human cyclin T1 generated using the cyclin K structure as a template reveals that the two proteins have similar structures, as expected from their high level of sequence identity. Nevertheless, their CDK9-interacting surfaces display significant structural differences, which could potentially be exploited for the design of cyclin-targeted inhibitors of the CDK9-cyclin K and CDK9-cyclin T1 complexes.

    Organizational Affiliation: 

    Molecular Medicine Laboratory and Macromolecular Crystallography Unit, Division of Experimental Medicine, Harvard Institutes of Medicine, Harvard Medical School, Boston, MA 02115, USA.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Cyclin KA258Homo sapiensMutation(s): 0 
Gene Names: CCNK, CPR4
Find proteins for O75909 (Homo sapiens)
Explore O75909 
Go to UniProtKB:  O75909
NIH Common Fund Data Resources
PHAROS:  O75909
GTEx:  ENSG00000090061
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT
Download Ideal Coordinates CCD File 
 B [auth A], C [auth A], D [auth A]ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.218 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.185 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 40.766α = 90
b = 69.186β = 93.3
c = 50.504γ = 90
Software Package:
Software NamePurpose
SOLVEphasing
REFMACrefinement
ADSCdata collection
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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View more in-depth experimental data

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-01-02
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance