Nucleotide sequence and phylogeny of a chloramphenicol acetyltransferase encoded by the plasmid pSCS7 from Staphylococcus aureus

Abstract

The nucleotide sequence of the chloramphenicol acetyltransferase gene (cat) and its regulatory region, encoded by the plasmid pSCS7 from Staphylococcus aureus, was determined. The structural cat gene encoded a protein of 209 amino acids, which represented one monomer of the enzyme chloramphenicol acetyltransferase (CAT). Comparisons between the amino acid sequences of the pSCS7-encoded CAT from S. aureus and the previously sequenced CAT variants from S. aureus, Staphylococcus intermedius, Staphylococcus haemolyticus, Bacillus pumilis, Clostridium difficile, Clostridium perfringens, Escherichia coli, Shigella flexneri, and Proteus mirabilis were performed. An alignment of CAT amino acid sequences demonstrated the presence of 34 conserved amino acids among all CAT variants. These conserved residues were considered for their possible roles in the structure and function of CAT. On the basis of the alignment, a phylogenetic tree was constructed. It demonstrated relatively large evolutionary distances between the CAT variants of enteric bacteria, Clostridium, Bacillus, and Staphylococcus species.

Diversity among the gram-positive acetyltransferases inactivating streptogramin A and structurally related compounds and characterization of a new staphylococcal determinant, vatB

“…The deduced amino acid sequences of these three genes are related by 47.4 to 58.5% identity. The fact that plasmid or chromosomal antibiotic re- sistance genes carried by enterococci can be transferred by conjugation in vitro into S. aureus recipients (9,11,33,46), as well as the fact that closely related genes or transposons are present in enterococci and staphylococci (4,7,18,31,37,45,56,61,65), suggests that genetic exchange may occur between these two genera in vivo. The three SgA r genes described to date may be distant derivatives of a parental gene inherited long ago by a staphylococcal or an enterococcal isolate.…”

Antimicrobial resistance in staphylococci from animals with particular reference to bovine Staphylococcus aureus, porcine Staphylococcus hyicus, and canine Staphylococcus intermedius

“…Only plasmids of the pC221-and the pC223-family have been isolated from staphylococci of animal origin [10, 12, 69, 74-77, 81, 83, 84, 86, 88]. With the exception of plasmid pSCS5 from S. haemolyticus [74], plasmids of the pC223-family are structurally closely related repJ-based replicons of 4.5-4.6 kbp [11,69,75,88]. In contrast, plasmids of the pC221-family share only the repD/cat region which is flanked by the recombination site B and the palindromic sequence palA as well as by the cat gene transcriptional terminator.…”

“…Both plasmids are believed to have developed by sitespecific recombination processes between a pC221-like Cm resistance plasmid and a pS194-analogous Sm resistance plasmid [76,77]. Comparative data on the catA gene and its gene product are only available for the determinants located on plasmids pC221 and pSCS6 of the pC221-family and plasmids pSCS5 and pSCS7 of the pC223 family [10,12,74,75].…”

Nucleotide sequence and phylogeny of the tet(L) tetracycline resistance determinant encoded by plasmid pSTE1 from Staphylococcus hyicus

“…Its regulatory region was located immediately 5' of the tet gene coding region and exhibited 97.3% nucleotide sequence homology to the regulatory region of the inducible tet gene encoded by the plasmid pTHT15 from B. stearothermophilus and 53.7% nucleotide sequence homology to the regulatory region of the inducible tet gene encoded by pT181 from S. aureus. Moreover, the structural elements identified in this regulatory region appeared to be very similar to those previously described for the regulatory regions of other inducible antibiotic resistance genes in staphylococci, such as cat genes specifying chloramphenicol resistance (Cmr) (3,4,46,47) or ern(M) genes specifying MLr (18). All these inducible genes seemed to be regulated via translational attenuation (28).…”