"tet(U)" is not a tetracycline resistance determinant.

The enterococcal plasmid pKQ10 has been reported to carry a poorly characterized tetracycline resistance determinant designated tet(U). However, in a series of studies intended to further characterize this determinant, we have been unable to substantiate the claim that tet(U) confers resistance to tetracyclines. In line with these results, bioinformatic analysis provides compelling evidence that "tet(U)" is in fact the misannotated 3' end of a gene encoding a rolling-circle replication initiator (Rep) protein.