Structure of the Pyocyanin Biosynthetic Protein PhzM

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.196 

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Structural and functional analysis of the pyocyanin biosynthetic protein PhzM from Pseudomonas aeruginosa.

Parsons, J.F.Greenhagen, B.T.Shi, K.Calabrese, K.Robinson, H.Ladner, J.E.

(2007) Biochemistry 46: 1821-1828

  • DOI: https://doi.org/10.1021/bi6024403
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Pyocyanin is a biologically active phenazine produced by the human pathogen Pseudomonas aeruginosa. It is thought to endow P. aeruginosa with a competitive growth advantage in colonized tissue and is also thought to be a virulence factor in diseases such as cystic fibrosis and AIDS where patients are commonly infected by pathogenic Pseudomonads due to their immunocompromised state. Pyocyanin is also a chemically interesting compound due to its unusual oxidation-reduction activity. Phenazine-1-carboxylic acid, the precursor to the bioactive phenazines, is synthesized from chorismic acid by enzymes encoded in a seven-gene cistron in P. aeruginosa and in other Pseudomonads. Phenzine-1-carboxylic acid is believed to be converted to pyocyanin by the sequential actions of the putative S-adenosylmethionine-dependent N-methyltransferase PhzM and the putative flavin-dependent hydroxylase PhzS. Here we report the 1.8 A crystal structure of PhzM determined by single anomalous dispersion. Unlike many methyltransferases, PhzM is a dimer in solution. The 36 kDa PhzM polypeptide folds into three domains. The C-terminal domain exhibits the alpha/beta-hydrolase fold typical of small molecule methyltransferases. Two smaller N-terminal domains form much of the dimer interface. Structural alignments with known methyltransferases show that PhzM is most similar to the plant O-methyltransferases that are characterized by an unusual intertwined dimer interface. The structure of PhzM contains no ligands, and the active site is open and solvent-exposed when compared to structures of similar enzymes. In vitro experiments using purified PhzM alone demonstrate that it has little or no ability to methylate phenzine-1-carboxylic acid. However, when the putative hydroxylase PhzS is included, pyocyanin is readily produced. This observation suggests that a mechanism has evolved in P. aeruginosa that ensures efficient production of pyocyanin via the prevention of the formation and release of an unstable and potentially deleterious intermediate.

  • Organizational Affiliation

    Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA. parsonsj@umbi.umd.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Probable phenazine-specific methyltransferase
A, B
334Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: phzM
EC: 2.1.1
Find proteins for Q9HWH2 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore Q9HWH2 
Go to UniProtKB:  Q9HWH2
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9HWH2
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.196 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.97α = 97.47
b = 62.41β = 105.37
c = 68.75γ = 108.09
Software Package:
Software NamePurpose
CrystalCleardata collection
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: 2006-10-24
    Type: Initial release
  • Version 1.1: 2007-10-11
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Source and taxonomy, Version format compliance
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references