Solution structure of the N-terminal domain of CarA repressor

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 20 
  • Conformers Submitted: 20 
  • Selection Criteria: all calculated structures submitted 

wwPDB Validation   3D Report Full Report

This is version 1.3 of the entry. See complete history


Structural basis for operator and antirepressor recognition by Myxococcus xanthus CarA repressor.

Navarro-Aviles, G.Jimenez, M.A.Perez-Marin, M.C.Gonzalez, C.Rico, M.Murillo, F.J.Elias-Arnanz, M.Padmanabhan, S.

(2007) Mol Microbiol 63: 980-994

  • DOI: https://doi.org/10.1111/j.1365-2958.2006.05567.x
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Blue light induces carotenogenesis in Myxococcus xanthus. The carB operon encodes all but one of the structural genes involved, and its expression is regulated by the CarA-CarS repressor-antirepressor pair. In the dark, CarA-operator binding represses carB. CarS, produced on illumination, interacts physically with CarA to dismantle the CarA-operator complex and activate carB. Both operator and CarS bind to the autonomously folded N-terminal domain of CarA, CarA(Nter), which in excess represses carB. Here, we report the NMR structure of CarA(Nter), and map residues that interact with operator and CarS by NMR chemical shift perturbations, and in vivo and in vitro analyses of site-directed mutants. We show CarA(Nter) adopts the winged-helix topology of MerR-family DNA-binding domains, and conserves the majority of the helix-turn-helix and wing contacts with DNA. Tellingly, helix alpha2 in CarA, a key element in operator DNA recognition, is also critical for interaction with CarS, implying that the CarA-CarS protein-protein and the CarA-operator protein-DNA interfaces overlap. Thus, binding of CarA to operator and to antirepressor are mutually exclusive, and CarA may discern structural features in the acidic CarS protein that resemble operator DNA. Repressor inactivation by occluding the DNA-binding region may be a recurrent mechanism of action for acidic antirepressors.

  • Organizational Affiliation

    Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, Murcia, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Find proteins for Q1DDV9 (Myxococcus xanthus (strain DK1622))
Explore Q1DDV9 
Go to UniProtKB:  Q1DDV9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ1DDV9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 20 
  • Conformers Submitted: 20 
  • Selection Criteria: all calculated structures submitted 

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-02-13
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.3: 2023-12-20
    Changes: Data collection, Database references, Other