3S9G

Structure of human Hexim1 (delta stammer) coiled coil domain


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.296 
  • R-Value Work: 0.236 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure and Dynamics of a Stabilized Coiled-Coil Domain in the P-TEFb Regulator Hexim1.

Bigalke, J.M.Dames, S.A.Blankenfeldt, W.Grzesiek, S.Geyer, M.

(2011) J.Mol.Biol. 414: 639-653

  • DOI: 10.1016/j.jmb.2011.10.022

  • PubMed Abstract: 
  • The positive transcription elongation factor P-TEFb mediates the transition from transcription initiation to productive elongation by phosphorylation of the C-terminal domain of RNA polymerase II. P-TEFb is negatively regulated by the cellular protei ...

    The positive transcription elongation factor P-TEFb mediates the transition from transcription initiation to productive elongation by phosphorylation of the C-terminal domain of RNA polymerase II. P-TEFb is negatively regulated by the cellular protein Hexim1 (hexamethylene bisacetamide-inducible protein 1), which is highly conserved in higher eukaryotes. The C-terminal coiled-coil domain of Hexim1 recognizes the Cyclin T subunit of P-TEFb, whereas a central PYNT motif is required to inhibit the cyclin-dependent kinase Cdk9 by a yet unknown mechanism. Here, the crystal structure of the Cyclin T-binding domain (TBD) of human Hexim1 was determined at 2.1 Å resolution using a deletion mutant of three residues in its central stammer motif. The structure showed a continuous parallel coiled-coil domain of nine hepta-repeats with a preceding helix encompassing up to 15 residues. Two uncommon residues at heptad a positions in the N-terminal part of the coiled-coil structure, Lys284 and Tyr291, stabilize the preceding helix by a tight intermolecular hydrogen bond network with residues of the opposing chain. These interactions delineate a characteristic turn between both helices that is supposed to mediate binding to Cyclin T1. Stabilization of the coiled-coil domain by deletion of the stammer region was confirmed by NMR spectroscopic and backbone dynamic analyses analyzing wild-type TBD and three mutant variants. This study thus provides structural insights into the recognition of the regulator protein Hexim1 by P-TEFb and the modulation of coiled-coil dynamics by specific discontinuities.


    Organizational Affiliation

    Max-Planck-Institut für molekulare Physiologie, Abteilung Physikalische Biochemie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Protein HEXIM1
A, B
104Homo sapiensMutation(s): 1 
Gene Names: HEXIM1 (CLP1, EDG1, HIS1, MAQ1)
Find proteins for O94992 (Homo sapiens)
Go to Gene View: HEXIM1
Go to UniProtKB:  O94992
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Free: 0.296 
  • R-Value Work: 0.236 
  • Space Group: I 4
Unit Cell:
Length (Å)Angle (°)
a = 70.770α = 90.00
b = 70.770β = 90.00
c = 90.960γ = 90.00
Software Package:
Software NamePurpose
SHELXSphasing
XSCALEdata scaling
XDSdata reduction
REFMACrefinement
ADSCdata collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-10-19
    Type: Initial release
  • Version 1.1: 2011-11-09
    Type: Database references
  • Version 1.2: 2011-12-21
    Type: Database references