3PQK

Crystal Structure of the transcriptional repressor BigR from Xylella fastidiosa


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.09 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.209 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Plant Pathogenic Bacteria Utilize Biofilm Growth-associated Repressor (BigR), a Novel Winged-helix Redox Switch, to Control Hydrogen Sulfide Detoxification under Hypoxia.

Guimaraes, B.G.Barbosa, R.L.Soprano, A.S.Campos, B.M.de Souza, T.A.Tonoli, C.C.Leme, A.F.Murakami, M.T.Benedetti, C.E.

(2011) J.Biol.Chem. 286: 26148-26157

  • DOI: 10.1074/jbc.M111.234039
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Winged-helix transcriptional factors play important roles in the control of gene expression in many organisms. In the plant pathogens Xylella fastidiosa and Agrobacterium tumefaciens, the winged-helix protein BigR, a member of the ArsR/SmtB family of ...

    Winged-helix transcriptional factors play important roles in the control of gene expression in many organisms. In the plant pathogens Xylella fastidiosa and Agrobacterium tumefaciens, the winged-helix protein BigR, a member of the ArsR/SmtB family of metal sensors, regulates transcription of the bigR operon involved in bacterial biofilm growth. Previous studies showed that BigR represses transcription of its own operon through the occupation of the RNA polymerase-binding site; however, the signals that modulate its activity and the biological function of its operon are still poorly understood. Here we show that although BigR is a homodimer similar to metal sensors, it functions as a novel redox switch that derepresses transcription upon oxidation. Crystal structures of reduced and oxidized BigR reveal that formation of a disulfide bridge involving two critical cysteines induces conformational changes in the dimer that remarkably alter the topography of the winged-helix DNA-binding interface, precluding DNA binding. This structural mechanism of DNA association-dissociation is novel among winged-helix factors. Moreover, we demonstrate that the bigR operon is required for hydrogen sulfide detoxification through the action of a sulfur dioxygenase (Blh) and sulfite exporter. As hydrogen sulfide strongly inhibits cytochrome c oxidase, it must be eliminated to allow aerobic growth under low oxygen tension, an environmental condition found in bacterial biofilms, xylem vessels, and root tissues. Accordingly, we show that the bigR operon is critical to sustain bacterial growth under hypoxia. These results suggest that BigR integrates the transcriptional regulation of a sulfur oxidation pathway to an oxidative signal through a thiol-based redox switch.


    Organizational Affiliation

    Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo CP6192, Brazil.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Biofilm growth-associated repressor
A, B, C, D, E, F
102Xylella fastidiosa (strain 9a5c)Mutation(s): 0 
Gene Names: bigR
Find proteins for Q9PFB1 (Xylella fastidiosa (strain 9a5c))
Go to UniProtKB:  Q9PFB1
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A, B, C, D, E, F
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.09 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.209 
  • Space Group: P 1
Unit Cell:
Length (Å)Angle (°)
a = 34.230α = 90.03
b = 34.230β = 90.00
c = 140.830γ = 120.03
Software Package:
Software NamePurpose
SHARPphasing
XDSdata scaling
MAR345dtbdata collection
BUSTERrefinement
XDSdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-06-01
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2011-08-03
    Type: Database references