The chloramphenicol acetyltransferase gene of Tn2424: a new breed of cat

Abstract

We have sequenced the gene coding for the chloramphenicol acetyltransferase of Tn2424 of plasmid NR79. This gene codes for a protein of 23,500 Da, and the derived protein sequence is similar to those of the chromosomal chloramphenicol acetyltransferases of Agrobacterium tumefaciens and Pseudomonas aeruginosa and of unidentified open reading frames, which may encode chloramphenicol acetyltransferases, adjacent to the ermG macrolide-lincosamide-streptogramin resistance gene of Bacillus sphaericus and the vgb virginiamycin resistance gene of Staphylococcus aureus. Weaker similarity to the LacA (thiogalactoside acetyltransferase) and CysE (serine acetyltransferase) proteins of Escherichia coli and the NodL protein of Rhizobium leguminosarum is also observed. There is no significant similarity to any other chloramphenicol acetyltransferase genes, such as that of Tn9. The Tn2424 cat gene is part of a 4.5-kb region which also contains the aacA1a aminoglycoside-6'-N-acetyltransferase gene; Tn2424 is similar to Tn21 except for the presence of this region. Sequences flanking the cat gene are typical of those flanking other genes inserted into pVS1-derived "integrons" by a site-specific recombinational mechanism.

New mobile gene cassettes containing an aminoglycoside resistance gene, aacA7, and a chloramphenicol resistance gene, catB3, in an integron in pBWH301

“…4), and these two proteins share 82.3% identity and 91.3% similarity. CATB3 also shares 67.4% identity (79.4% similarity) with CATB1, which was found in a Cm r isolate of A. tumefaciens and is not cassette determined (39), and 68.4% identity (84.4% similarity) with the product of an open reading frame (Ps orf) found in the chromosome of P. aeruginosa PAO1 (31).…”

“…2). This protein is a member of a recently identified family of CATs, here designated CATB proteins, that are not related to the majority of previously identified CATs (31,39). The new determinant, as the third identified member of this family, is designated CATB3 (catB3).…”

“…The AAC(6Ј)-I enzyme encoded by the aacA7 gene is a member of one of the three known families of AAC(6Ј)-I enzymes (35). The catB3 gene encodes a chloramphenicol acetyltransferase (CAT) that is a member of a recently identified family of CAT proteins (31,39). The catB gene family includes three cassetteassociated genes and a non-cassette-associated gene isolated from a chloramphenicol-resistant isolate of Agrobacterium tumefaciens.…”

Nucleotide sequence and genetic analysis of the neuD and neuB genes in region 2 of the polysialic acid gene cluster of Escherichia coli K1

“…NeuD shows significant similarity to a family of bacterial acetyltransferases that includes LacA and CysE of E. coli, NodL of Rhizobium leguminosarum (11), and the Tn2424 chloramphenicol acetyltransferase protein (24) (Fig. 5).…”

Attachment of Agrobacterium tumefaciens to carrot cells and Arabidopsis wound sites is correlated with the presence of a cell-associated, acidic polysaccharide

“…A BlastX search showed that the protein has homology to transacetylases from a Synechocystis sp. (68% similarity, 45% identity) (17), Enterococcus faecium satA (62% similarity, 40% identity) (29), A. tumefaciens cat (62% similarity, 40% identity) (43), Enterobacter aerogenes catB4 pBWH301 (61% similarity, 35% identity) (27), E. coli cat pNR79 (60% similarity, 38% identity) (27), and many other bacteria (Fig. 1).…”