An N-terminal domain of the tetracycline resistance protein increases susceptibility to aminoglycosides and complements potassium uptake defects in Escherichia coli.

Expression of extrachromosomal tet genes increased the susceptibility of gram-negative bacteria to specific aminoglycoside antibiotics. The magnitude of the increase in susceptibility was dependent on the amount and the class of the tet gene product (designated Tet) and the bacterial species in which the tet gene was expressed. Truncated Tet proteins that contained more than the first 33, but not more than the first 97, N-terminal amino acids of Tet also increased the susceptibility to aminoglycosides and complemented the potassium uptake defects in Escherichia coli. The primary structure of this N-terminal Tet fragment has the hydropathic characteristics of a multimeric, transmembrane structure and is highly conserved in three different classes of Tet proteins.