Crystal Structure of Thermus aquaticus RNA Polymerase Sigma Subunit Fragment, Region 4

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.218 
  • R-Value Observed: 0.218 

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Structure of the bacterial RNA polymerase promoter specificity sigma subunit.

Campbell, E.A.Muzzin, O.Chlenov, M.Sun, J.L.Olson, C.A.Weinman, O.Trester-Zedlitz, M.L.Darst, S.A.

(2002) Mol Cell 9: 527-539

  • DOI: https://doi.org/10.1016/s1097-2765(02)00470-7
  • Primary Citation of Related Structures:  
    1KU2, 1KU3, 1KU7

  • PubMed Abstract: 

    The sigma subunit is the key regulator of bacterial transcription. Proteolysis of Thermus aquaticus sigma(A), which occurred in situ during crystallization, reveals three domains, sigma(2), sigma(3), and sigma(4), connected by flexible linkers. Crystal structures of each domain were determined, as well as of sigma(4) complexed with -35 element DNA. Exposed surfaces of each domain are important for RNA polymerase binding. Universally conserved residues important for -10 element recognition and melting lie on one face of sigma(2), while residues important for extended -10 recognition lie on sigma(3). Genetic studies correctly predicted that a helix-turn-helix motif in sigma(4) recognizes the -35 element but not the details of the protein-DNA interactions. Positive control mutants in sigma(4) cluster in two regions, positioned to interact with activators bound just upstream or downstream of the -35 element.

  • Organizational Affiliation

    Laboratory of Molecular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
sigma factor sigA73Thermus aquaticusMutation(s): 1 
Find proteins for Q9EZJ8 (Thermus aquaticus)
Explore Q9EZJ8 
Go to UniProtKB:  Q9EZJ8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9EZJ8
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.218 
  • R-Value Observed: 0.218 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 39.804α = 90
b = 39.804β = 90
c = 66.807γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-04-03
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Database references
  • Version 1.4: 2024-02-14
    Changes: Data collection