2PK2

Cyclin box structure of the P-TEFb subunit Cyclin T1 derived from a fusion complex with EIAV Tat

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.67 Å
  • R-Value Free: 0.306 
  • R-Value Work: 0.274 

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This is version 1.3 of the entry. See complete history. 

Literature

Cyclin Box Structure of the P-TEFb Subunit Cyclin T1 Derived from a Fusion Complex with EIAV Tat.

Anand, K., Schulte, A., Fujinaga, K., Scheffzek, K., Geyer, M.

(2007) J.Mol.Biol. 370: 826-836

  • DOI: 10.1016/j.jmb.2007.04.077

  • PubMed Abstract: 

    • The positive transcription elongation factor b (P-TEFb) is an essential regulator of viral gene expression during the life cycle of human immunodeficiency virus type 1 (HIV-1). Its cyclin T1 subunit forms a ternary complex with the viral transcriptio ...

    The positive transcription elongation factor b (P-TEFb) is an essential regulator of viral gene expression during the life cycle of human immunodeficiency virus type 1 (HIV-1). Its cyclin T1 subunit forms a ternary complex with the viral transcriptional transactivator (Tat) protein and the transactivation response (TAR) RNA element thereby activating cyclin dependent kinase 9 (Cdk9), which stimulates transcription at the level of chain elongation. We report the structure of the cyclin box domain of human cyclin T1 at a resolution of 2.67 A. The structure was obtained by crystallographic analysis of a fusion protein composed of cyclin T1 linked to the transactivator protein Tat from equine infectious anemia virus (EIAV), which is functionally and structurally related to HIV-1 Tat. The conserved cyclin box domain of cyclin T1 exhibits structural features for interaction with physiological binding partners such as Cdk9. A recognition site for Cdk/Cyclin substrates is partly covered by a cyclin T-specific insert, suggesting specific interactions with regulatory factors. The previously identified Tat/TAR recognition motif (TRM) forms a C-terminal helix that is partly occluded in the cyclin box repeat interface, while cysteine 261 is accessible to form an intermolecular zinc finger with Tat. Residues of the TRM contribute to a positively charged groove that may directly attract RNA molecules. The EIAV Tat protein instead appeared undefined from the electron density map suggesting that it is highly disordered. Functional experiments confirmed the TAR binding properties of the fusion protein and suggested residues on the second cyclin box repeat to contribute to Tat stimulated transcription.

    Organizational Affiliation: 

    EMBL Heidelberg, Structural and Computational Biology & Developmental Biology Unit, 69117 Heidelberg, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cyclin-T1, Protein Tat
A, B, C, D
358Equine infectious anemia virus (isolate CL22), Homo sapiens
This entity is chimeric		Mutation(s): 0 
Gene Names: tat, CCNT1
Find proteins for P32544 (Equine infectious anemia virus (isolate CL22))
Go to UniProtKB:  P32544
Find proteins for O60563 (Homo sapiens)
Go to Gene View: CCNT1
Go to UniProtKB:  O60563
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.67 Å
  • R-Value Free: 0.306 
  • R-Value Work: 0.274 
  • Space Group: H 3
Unit Cell:
Length (Å)Angle (°)
a = 203.830α = 90.00
b = 203.830β = 90.00
c = 124.790γ = 120.00
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling
SHELXL-97refinement
ADSCdata collection
PHASERphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-07-03
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-07-26
    Type: Refinement description, Source and taxonomy