4ZUA

Crystal structure of the ExsA regulatory domain


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.268 
  • R-Value Work: 0.239 
  • R-Value Observed: 0.241 

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This is version 1.1 of the entry. See complete history


Literature

Structural Analysis of the Regulatory Domain of ExsA, a Key Transcriptional Regulator of the Type Three Secretion System in Pseudomonas aeruginosa.

Shrestha, M.Xiao, Y.Robinson, H.Schubot, F.D.

(2015) PLoS One 10: e0136533-e0136533

  • DOI: 10.1371/journal.pone.0136533
  • Primary Citation of Related Structures:  
    4ZUA

  • PubMed Abstract: 
  • Pseudomonas aeruginosa employs a type three secretion system to facilitate infections in mammalian hosts. The operons encoding genes of structural components of the secretion machinery and associated virulence factors are all under the control of the AraC-type transcriptional activator protein, ExsA ...

    Pseudomonas aeruginosa employs a type three secretion system to facilitate infections in mammalian hosts. The operons encoding genes of structural components of the secretion machinery and associated virulence factors are all under the control of the AraC-type transcriptional activator protein, ExsA. ExsA belongs to a unique subfamily of AraC-proteins that is regulated through protein-protein contacts rather than small molecule ligands. Prior to infection, ExsA is inhibited through a direct interaction with the anti-activator ExsD. To activate ExsA upon host cell contact this interaction is disrupted by the anti-antiactivator protein ExsC. Here we report the crystal structure of the regulatory domain of ExsA, which is known to mediate ExsA dimerization as well as ExsD binding. The crystal structure suggests two models for the ExsA dimer. Both models confirmed the previously shown involvement of helix α-3 in ExsA dimerization but one also suggest a role for helix α-2. These structural data are supported by the observation that a mutation in α-2 greatly diminished the ability of ExsA to activate transcription in vitro. Additional in vitro transcription studies revealed that a conserved pocket, used by AraC and the related ToxT protein for the binding of small molecule regulators, although present in ExsA is not involved in binding of ExsD.


    Organizational Affiliation

    Department of Biological Sciences, Virginia Polytechnic Institute & State University, Washington Street, Blacksburg, VA 24060, United States of America.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Exoenzyme S synthesis regulatory protein ExsAA, B178Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: exsAPA1713
UniProt
Find proteins for P26993 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore P26993 
Go to UniProtKB:  P26993
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP26993
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.268 
  • R-Value Work: 0.239 
  • R-Value Observed: 0.241 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 69.949α = 90
b = 69.949β = 90
c = 191.802γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
MOSFLMdata reduction
PHENIXphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2016-02-03
    Type: Initial release
  • Version 1.1: 2016-07-20
    Changes: Data collection