A DNA sequence upstream of the tet(O) gene is required for full expression of tetracycline resistance

The DNA sequences upstream of the tet(O) and tet(M) open reading frames (ORFs) (ca. 300 bp) were found to share a higher degree of homology than those of the tet(O) and tet(M) ORFs themselves. A transcription initiation site for tel(O) was located by primer extension analysis. Campylobacter coli was found to use a promoter sequence different from that used by Escherichia coli. The sequence upstream of tet(O) was shown to be required in cis for high-level resistance to tetracycline. The class 0 tetracycline (TC) resistance determinant [tet(O)] has been identified in Campylobacter spp. (18, 20), Streptococcus mutans (9), and Enterococcus faecium (1). The determinant has been cloned and expressed in Esche-richia coli (9, 18, 20). The deduced amino acid sequence of Tet(O) is very similar to that of Tet(M) (76 % identity [13]), which has been found in a wide variety of gram-positive and gram-negative bacteria (21). The sequences of several tet(O) and tet(M) genes hav