On the evolution of Tn21-like multiresistance transposons: sequence analysis of the gene (aacC1) for gentamicin acetyltransferase-3-I(AAC(3)-I), another member of the Tn21-based expression cassette

Mol Gen Genet. 1989 Jun;217(2-3):202-8. doi: 10.1007/BF02464882.


The aminoglycoside-3-O-acetyltransferase-I gene (aacC1) from R plasmids of two incompatibility groups (R1033 [Tn1696], and R135) was cloned and sequenced. In the case of R1033, it was shown that the aacC gene is coded by a precise insertion of 833 bp between the aadA promoter and its structural gene in a Tn21 related transposon (Tn1696). This insertion occurs at the same target sequence as that of the OXA-1 beta-lactamase gene insertion in Tn2603. Upstream of the aacC gene, we found an open reading frame (ORF) which is probably implicated in the site-specific recombinational events involved in the evolution of this family of genetic elements. These results provide additional confirmation of the role of Tn21 elements as naturally occurring interspecific transposition and expression cassettes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetyltransferases / genetics*
  • Amino Acid Sequence
  • Base Sequence
  • Biological Evolution
  • DNA Transposable Elements*
  • DNA, Bacterial / genetics
  • Drug Resistance, Microbial / genetics
  • Molecular Sequence Data
  • R Factors*
  • Sequence Homology, Nucleic Acid


  • DNA Transposable Elements
  • DNA, Bacterial
  • Acetyltransferases
  • gentamicin 3-acetyltransferase

Associated data

  • GENBANK/X15852