2GD7

The Structure of the Cyclin T-binding domain of Hexim1 reveals the molecular basis for regulation of transcription elongation


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Structure of the Cyclin T binding domain of Hexim1 and molecular basis for its recognition of P-TEFb.

Dames, S.A.Schonichen, A.Schulte, A.Barboric, M.Peterlin, B.M.Grzesiek, S.Geyer, M.

(2007) Proc Natl Acad Sci U S A 104: 14312-14317

  • DOI: https://doi.org/10.1073/pnas.0701848104
  • Primary Citation of Related Structures:  
    2GD7

  • PubMed Abstract: 

    Hexim1 is a cellular protein that associates with the positive transcription elongation factor b (P-TEFb) to regulate RNA polymerase II elongation of nascent mRNA transcripts. It directly binds to Cyclin T1 of P-TEFb and inhibits the kinase activity of Cdk9, leading to an arrest of transcription elongation. Here, we report the solution structure of the Cyclin T binding domain (TBD) of Hexim1 that forms a parallel coiled-coil homodimer composed of two segments and a preceding alpha helix that folds back onto the first coiled-coil unit. NMR titration, fluorescence, and immunoprecipitation experiments revealed the binding interface to Cyclin T1, which covers a large surface on the first coiled-coil segment. Electrostatic interactions between an acidic patch on Hexim1 and positively charged residues of Cyclin T1 drive the complex formation that is confirmed by mutagenesis data on Hexim1 mediated transcription regulation in cells. Thus, our studies provide structural insights how Hexim1 recognizes the Cyclin T1 subunit of P-TEFb, which is a key step toward the regulation of transcription elongation.


  • Organizational Affiliation

    Department of Structural Biology, Biozentrum Basel, University of Basel, 4003 Basel, Switzerland. sonja.dames@unibas.ch


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
HEXIM1 protein
A, B
107Homo sapiensMutation(s): 1 
Gene Names: Hexim1 (255-359)G256A
UniProt & NIH Common Fund Data Resources
Find proteins for O94992 (Homo sapiens)
Explore O94992 
Go to UniProtKB:  O94992
PHAROS:  O94992
GTEx:  ENSG00000186834 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO94992
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

  • Released Date: 2007-06-12 
  • Deposition Author(s): Dames, S.A.

Revision History  (Full details and data files)

  • Version 1.0: 2007-06-12
    Type: Initial release
  • Version 1.1: 2007-09-17
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.4: 2024-05-29
    Changes: Data collection