Cloning of genes involved in carbazole degradation of Pseudomonas sp. strain CA10: nucleotide sequences of genes and characterization of meta-cleavage enzymes and hydrolase

J Bacteriol. 1997 Aug;179(15):4841-9. doi: 10.1128/jb.179.15.4841-4849.1997.


The DNA fragment encoding meta-cleavage enzymes and the meta-cleavage compound hydrolase, involved in carbazole degradation, was cloned from the carbazole-utilizing bacterium Pseudomonas sp. strain CA10. DNA sequence analysis of this 2.6-kb SmaI-SphI fragment revealed that there were three open reading frames (ORF1, ORF2, and ORF3, in this gene order). ORF1 and ORF2 were indispensable for meta-cleavage activity for 2'-aminobiphenyl-2,3-diol and its easily available analog, 2,3-dihydroxybiphenyl, and were designated carBa and carBb, respectively. The alignment of CarBb with other meta-cleavage enzymes indicated that CarBb may have a non-heme iron cofactor coordinating site. On the basis of the phylogenetic tree, CarBb was classified as a member of the protocatechuate 4,5-dioxygenase family. This unique extradiol dioxygenase, CarB, had significantly higher affinity and about 20-times-higher meta-cleavage activity for 2,3-dihydroxybiphenyl than for catechol derivatives. The putative polypeptide encoded by ORF3 was homologous with meta-cleavage compound hydrolases in other bacteria, and ORF3 was designated carC. The hydrolase activity of CarC for 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid, the meta-cleavage compound of 2,3-dihydroxybiphenyl, was 40 times higher than that for 2-hydroxy-6-oxohepta-2,4-dienoic acid, the meta-cleavage compound of 3-methylcatechol. Alignment analysis and the phylogenetic tree indicate that CarC has greatest homologies with hydrolases involved in the monoaromatic compound degradation pathway. These results suggest the possibility that CarC is a novel type of hydrolase.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Blotting, Southern
  • Carbazoles / metabolism*
  • Chromosome Mapping
  • Cloning, Molecular
  • DNA, Bacterial
  • Dioxygenases*
  • Gene Deletion
  • Genes, Bacterial
  • Genetic Complementation Test
  • Hydrolases / genetics*
  • Molecular Sequence Data
  • Open Reading Frames
  • Oxygenases / genetics*
  • Pseudomonas / enzymology*
  • Pseudomonas / genetics
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid


  • Carbazoles
  • DNA, Bacterial
  • carbazole
  • Oxygenases
  • Dioxygenases
  • protocatechuate 4,5-dioxygenase
  • Hydrolases

Associated data

  • GENBANK/D89064
  • GENBANK/D89065