Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 88.12 kDa 
• Atom Count: 6049 
• Modelled Residue Count: 767 
• Deposited Residue Count: 786 
• Unique protein chains: 1

2WK7

Structure of apo form of Vibrio cholerae CqsA

• PDB DOI: 10.2210/pdb2WK7/pdb

• Classification: TRANSFERASE
• Organism(s): Vibrio cholerae O1 biovar El Tor str. N16961
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2009-06-08 Released: 2009-07-21 
• Deposition Author(s): Jahan, N., Potter, J.A., Sheikh, M.A., Botting, C.H., Shirran, S.L., Westwood, N.J., Taylor, G.L.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.286 
• R-Value Work: 0.206 
• R-Value Observed: 0.210 

Literature

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

• PubMed: 19631226 
• DOI: 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.

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Organizational Affiliation: 

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

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
CAI-1 AUTOINDUCER SYNTHASE	A, B	393	Vibrio cholerae O1 biovar El Tor str. N16961	Mutation(s): 0  Gene Names: cqsA, VC_A0523 EC: 2.3
UniProt
Find proteins for Q9KM65 (Vibrio cholerae serotype O1 (strain ATCC 39315 / El Tor Inaba N16961)) Explore Q9KM65  Go to UniProtKB:  Q9KM65

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
SO4	C [auth A], D [auth B]	SULFATE ION O4 S QAOWNCQODCNURD-UHFFFAOYSA-L

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.286 
• R-Value Work: 0.206 
• R-Value Observed: 0.210 
• Space Group: P 2₁ 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 177.314	α = 90
b = 70.077	β = 90
c = 70.703	γ = 90

Software Package:

Software Name	Purpose
PHENIX	refinement
PHASER	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2009-06-08 
• Released Date: 2009-07-21 
Deposition Author(s): Jahan, N., Potter, J.A., Sheikh, M.A., Botting, C.H., Shirran, S.L., Westwood, N.J., Taylor, G.L.

Revision History  

• 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