In vitro and in vivo characterization of the Pseudomonas aeruginosa cyclic AMP (cAMP) phosphodiesterase CpdA, required for cAMP homeostasis and virulence factor regulation

J Bacteriol. 2010 Jun;192(11):2779-90. doi: 10.1128/JB.00168-10. Epub 2010 Mar 26.


Cyclic AMP (cAMP) is an important second messenger signaling molecule that controls a wide variety of eukaryotic and prokaryotic responses to extracellular cues. For cAMP-dependent signaling pathways to be effective, the intracellular cAMP concentration is tightly controlled at the level of synthesis and degradation. In the opportunistic human pathogen Pseudomonas aeruginosa, cAMP is a key regulator of virulence gene expression. To better understand the role of cAMP homeostasis in this organism, we identified and characterized the enzyme CpdA, a putative cAMP phosphodiesterase. We demonstrate that CpdA possesses 3',5'-cAMP phosphodiesterase activity in vitro and that it utilizes an iron-dependent catalytic mechanism. Deletion of cpdA results in the accumulation of intracellular cAMP and altered regulation of P. aeruginosa virulence traits. Further, we demonstrate that the cAMP-dependent transcription factor Vfr directly regulates cpdA expression in response to intracellular cAMP accumulation, thus providing a feedback mechanism for controlling cAMP levels and fine-tuning virulence factor expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3',5'-Cyclic-AMP Phosphodiesterases / chemistry
  • 3',5'-Cyclic-AMP Phosphodiesterases / genetics
  • 3',5'-Cyclic-AMP Phosphodiesterases / metabolism*
  • ADP Ribose Transferases / genetics
  • ADP Ribose Transferases / metabolism
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacterial Toxins / genetics
  • Bacterial Toxins / metabolism
  • Blotting, Western
  • Chromatography, Gel
  • Cyclic AMP / metabolism*
  • Cyclic AMP Receptor Protein / genetics
  • Cyclic AMP Receptor Protein / metabolism
  • DNA Footprinting
  • Electrophoretic Mobility Shift Assay
  • Exotoxins / genetics
  • Exotoxins / metabolism
  • Gene Expression Regulation, Bacterial / genetics
  • Gene Expression Regulation, Bacterial / physiology
  • Iron / metabolism
  • Molecular Sequence Data
  • Peptide Hydrolases / genetics
  • Peptide Hydrolases / metabolism
  • Pseudomonas aeruginosa / enzymology*
  • Pseudomonas aeruginosa / genetics
  • Pseudomonas aeruginosa / metabolism*
  • Sequence Homology, Amino Acid
  • Virulence Factors / genetics*
  • Virulence Factors / metabolism


  • Bacterial Proteins
  • Bacterial Toxins
  • Cyclic AMP Receptor Protein
  • Exotoxins
  • Vfr protein, Pseudomonas aeruginosa
  • Virulence Factors
  • Cyclic AMP
  • Iron
  • ADP Ribose Transferases
  • Pseudomonas aeruginosa exotoxin A
  • exoenzyme S
  • 3',5'-Cyclic-AMP Phosphodiesterases
  • Peptide Hydrolases
  • protease IV

Associated data

  • GENBANK/GU551724