Structure of holo form of Vibrio cholerae CqsA

Experimental Data Snapshot

  • Resolution: 2.10 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.201 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.4 of the entry. See complete history


Insights Into the Biosynthesis of the Vibrio Cholerae Major Autoinducer Cai-1 from the Crystal Structure of the Plp-Dependent Enzyme Cqsa.

Jahan, N.Potter, J.A.Sheikh, M.A.Botting, C.H.Shirran, S.L.Westwood, N.J.Taylor, G.L.

(2009) J Mol Biol 392: 763

  • DOI: https://doi.org/10.1016/j.jmb.2009.07.042
  • Primary Citation of Related Structures:  
    2WK7, 2WK8, 2WK9, 2WKA

  • PubMed Abstract: 

    CqsA is an enzyme involved in the biosynthesis of cholerae autoinducer-1 (CAI-1), the major Vibrio cholerae autoinducer engaged in quorum sensing. The amino acid sequence of CqsA suggests that it belongs to the family of alpha-oxoamine synthases that catalyse the condensation of an amino acid to an acyl-CoA substrate. Here we present the apo- and PLP-bound crystal structures of CqsA and confirm that it shares structural homology with the dimeric alpha-oxoamine synthases, including a conserved PLP-binding site. The chemical structure of CAI-1 suggests that decanoyl-CoA may be one substrate of CqsA and that another substrate may be l-threonine or l-2-aminobutyric acid. A crystal structure of CqsA at 1.9-A resolution obtained in the presence of PLP and l-threonine reveals an external aldimine that has lost the l-threonine side chain. Similarly, a 1.9-A-resolution crystal structure of CqsA in the presence of PLP, l-threonine, and decanoyl-CoA shows a trapped external aldimine intermediate, suggesting that the condensation and decarboxylation steps have occurred, again with loss of the l-threonine side chain. It is suggested that this side-chain loss, an observation supported by mass spectrometry, is due to a retro-aldol reaction. Although no structural data have been obtained on CqsA using l-2-aminobutyric acid and decanoyl-CoA as substrates, mass spectrometry confirms the expected product of the enzyme reaction. It is proposed that a region of structure that is disordered in the apo structure is involved in the release of product. While not confirming if CqsA alone is able to synthesize CAI-1, these results suggest possible synthetic routes.

  • Organizational Affiliation

    Centre for Biomolecular Sciences, University of St. Andrews, UK.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
389Vibrio cholerae O1 biovar El Tor str. N16961Mutation(s): 0 
EC: 2.3
Find proteins for Q9KM65 (Vibrio cholerae serotype O1 (strain ATCC 39315 / El Tor Inaba N16961))
Explore Q9KM65 
Go to UniProtKB:  Q9KM65
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9KM65
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.10 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.201 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 177.337α = 90
b = 70.134β = 90
c = 70.625γ = 90
Software Package:
Software NamePurpose

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-07-21
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2018-03-07
    Changes: Source and taxonomy
  • Version 1.4: 2024-05-08
    Changes: Data collection, Database references, Derived calculations, Other