Characterisation of a chloramphenicol acetyltransferase determinant found in the chromosome of Pseudomonas aeruginosa

Peter A. White, H. W. Stokes*, Kim L. Bunny, Ruth M. Hall

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


The open reading frame (ORF) in the Pseudomonas aeruginosa chromosome, whose product resembles the chloramphenicol acetyltransferases (CAT) belonging to the CATB family, was cloned and shown to confer resistance to chloramphenicol (Cm) in Escherichia coli. The determinant was therefore named catB7 and the corresponding protein CATB7. When the copy number and expression signals were identical, the catB7 gene conferred resistance to Cm at a level slightly lower than those of three other catB genes. CATB7 resembles other CATBs in that it acetylates Cm but not 1-acetoxy-Cm. For CATB7, the K(m) values for acetyl-CoA and Cm were 5.0-5.4-fold higher than the corresponding values for each of the three other CATB proteins (CATB1, CATB3 and CATB5) examined and the V(max) was 5-6 fold lower. Using PCR, the catB7 gene was found in all six P. aeruginosa strains examined but not in any other species of pseudomonad tested. Weak CAT activity was detected in crude cell extracts from five of the six P. aeruginosa strains. However, this activity did not correlate with the Cm susceptibility of the strains, indicating that catB7 is not likely to be the major determinant of intrinsic Cm resistance in P. aeruginosa. Copyright (C) 1999 Federation of European Microbiological Societies.

Original languageEnglish
Pages (from-to)27-35
Number of pages9
JournalFEMS Microbiology Letters
Issue number1
Publication statusPublished - 1 Jun 1999


  • Acetyltransferase
  • catB7
  • Chloramphenicol resistance
  • Pseudomonas aeruginosa


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