Abstract
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 tet(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.