3H76

Crystal structure of PqsD, a key enzyme in Pseudomonas aeruginosa quinolone signal biosynthesis pathway


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.202 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structure of PqsD, a Pseudomonas quinolone signal biosynthetic enzyme, in complex with anthranilate.

Bera, A.K.Atanasova, V.Robinson, H.Eisenstein, E.Coleman, J.P.Pesci, E.C.Parsons, J.F.

(2009) Biochemistry 48: 8644-8655

  • DOI: https://doi.org/10.1021/bi9009055
  • Primary Citation of Related Structures:  
    3H76, 3H77, 3H78

  • PubMed Abstract: 

    Pseudomonas quinolone signal (PQS), 2-heptyl-3-hydroxy-4-quinolone, is an intercellular alkyl quinolone signaling molecule produced by the opportunistic pathogen Pseudomonas aeruginosa. Alkyl quinolone signaling is an atypical system that, in P. aeruginosa, controls the expression of numerous virulence factors. PQS is synthesized from the tryptophan pathway intermediate, anthranilate, which is derived either from the kynurenine pathway or from an alkyl quinolone specific anthranilate synthase encoded by phnAB. Anthranilate is converted to PQS by the enzymes encoded by the pqsABCDE operon and pqsH. PqsA forms an activated anthraniloyl-CoA thioester that shuttles anthranilate to the PqsD active site where it is transferred to Cys112 of PqsD. In the only biochemically characterized reaction, a condensation then occurs between anthraniloyl-PqsD and malonyl-CoA or malonyl-ACP, a second PqsD substrate, forming 2,4-dihydroxyquinoline (DHQ). The role PqsD plays in the biosynthesis of other alkyl quinolones, such as PQS, is unclear, though it has been reported to be required for their production. No evidence exists that DHQ is a PQS precursor, however. Here we present a structural and biophysical characterization of PqsD that includes several crystal structures of the enzyme, including that of the PqsD-anthranilate covalent intermediate and the inactive Cys112Ala active site mutant in complex with anthranilate. The structure reveals that PqsD is structurally similar to the FabH and chalcone synthase families of fatty acid and polyketide synthases. The crystallographic asymmetric unit contains a PqsD dimer. The PqsD monomer is composed of two nearly identical approximately 170-residue alphabetaalphabetaalpha domains. The structures show anthranilate-liganded Cys112 is positioned deep in the protein interior at the bottom of an approximately 15 A long channel while a second anthraniloyl-CoA molecule is waiting in the cleft leading to the protein surface. Cys112, His257, and Asn287 form the FabH-like catalytic triad of PqsD. The C112A mutant is inactive, although it still reversibly binds anthraniloyl-CoA. The covalent complex between anthranilate and Cys112 clearly illuminates the orientation of key elements of the PqsD catalytic machinery and represents a snapshot of a key point in the catalytic cycle.


  • Organizational Affiliation

    Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
PQS biosynthetic enzyme
A, B
359Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: pqsDPA0999
EC: 2.3.1.180
UniProt
Find proteins for P20582 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore P20582 
Go to UniProtKB:  P20582
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP20582
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.202 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 49.081α = 90
b = 90.42β = 95.38
c = 67.894γ = 90
Software Package:
Software NamePurpose
CrystalCleardata collection
PHASERphasing
REFMACrefinement
d*TREKdata reduction
d*TREKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-09-15
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-09-06
    Changes: Data collection, Database references, Refinement description