Chloramphenicol acetyltransferase gene of staphylococcal plasmid pC221. Nucleotide sequence analysis and expression studies.

The nucleotide sequence of the inducible chloramphenicol acetyltransferase gene (cat) of Staphylococcus aureus plasmid pC221 has been determined. The deduced primary structure for the 215 residue polypeptide (25.9 kDa) is in agreement with partial amino acid sequence data on the purified protein, previously designated as the type C variant of CAT. In common with the inducible cat elements of pC194 and B. pumilus, the 5' non-coding region of the cat of pC221 contains an inverted complementary repeat ('stem-loop' or 'hairpin') which may sequester the predicted ribosome bonding site of the mRNA. The likely transcription initiation site has been determined in vitro using purified B. subtilis RNA polymerase. Recombinant plasmids carrying the cat of pC221 on a 1156 bp TaqI fragment are expressed inefficiently in Escherichia coli, wherein induction is both poor and orientation-specific.