Chlorocatechols substituted at positions 4 and 5 are substrates of the broad-spectrum chlorocatechol 1,2-dioxygenase of Pseudomonas chlororaphis RW71

J Bacteriol. 2001 Feb;183(3):997-1011. doi: 10.1128/JB.183.3.997-1011.2001.


The nucleotide sequence of a 10,528-bp region comprising the chlorocatechol pathway gene cluster tetRtetCDEF of the 1,2,3,4-tetrachlorobenzene via the tetrachlorocatechol-mineralizing bacterium Pseudomonas chlororaphis RW71 (T. Potrawfke, K. N. Timmis, and R.-M. Wittich, Appl. Environ. Microbiol. 64:3798-3806, 1998) was analyzed. The chlorocatechol 1,2-dioxygenase gene tetC was cloned and overexpressed in Escherichia coli. The recombinant gene product was purified, and the alpha,alpha-homodimeric TetC was characterized. Electron paramagnetic resonance measurements confirmed the presence of a high-spin-state Fe(III) atom per monomer in the holoprotein. The productive transformation by purified TetC of chlorocatechols bearing chlorine atoms in positions 4 and 5 provided strong evidence for a significantly broadened substrate spectrum of this dioxygenase compared with other chlorocatechol dioxygenases. The conversion of 4,5-dichloro- or tetrachlorocatechol, in the presence of catechol, displayed strong competitive inhibition of catechol turnover. 3-Chlorocatechol, however, was simultaneously transformed, with a rate similar to that of the 4,5-halogenated catechols, indicating similar specificity constants. These novel characteristics of TetC thus differ significantly from results obtained from hitherto analyzed catechol 1,2-dioxygenases and chlorocatechol 1,2-dioxygenases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoenzymes
  • Biodegradation, Environmental
  • Catechols / metabolism
  • Chlorobenzenes / metabolism
  • Dioxygenases*
  • Electron Spin Resonance Spectroscopy
  • Evolution, Molecular
  • Genes, Bacterial
  • Holoenzymes
  • Iron / analysis
  • Kinetics
  • Models, Biological
  • Multigene Family
  • Oxygenases / chemistry
  • Oxygenases / genetics
  • Oxygenases / metabolism*
  • Pseudomonas / enzymology*
  • Recombinant Proteins / metabolism
  • Spectrophotometry
  • Substrate Specificity


  • Apoenzymes
  • Catechols
  • Chlorobenzenes
  • Holoenzymes
  • Recombinant Proteins
  • 3,4,5,6-tetrachlorocatechol
  • 3,4,5-trichlorocatechol
  • Iron
  • Oxygenases
  • Dioxygenases
  • chlorocatechol 1,2-dioxygenase
  • 1,2,3,4-tetrachlorobenzene
  • 4,5-dichlorocatechol