We have previously examined the genetic organization and regulation of the Tn10 tetracycline-resistance determinant in Escherichia coli K-12. The structural genes for tetA, the Tn10 tetracycline-resistance function, and for tetR, the Tn10 tet repressor, are transcribed in opposite directions from promoters in a regulatory region located between the two structural genes. Expression of both tetA ...

For most experimental and therapeutic applications of gene transfer, regulation of the timing and level of gene expression is preferable to constitutive gene expression. Among the systems that have been developed for pharmacologically controlled gene expression in mammalian cells, the bacterial tetracycline (tet)-responsive system has the advantage that it is dependent on a drug (tet) that is b...

Recombinant adeno-associated virus (rAAV) are effective gene delivery vehicles that can mediate long-lasting transgene expression. However, tight regulation and tissue-specific transgene expression is required for certain therapeutic applications. For regulatable expression from the liver we designed a hepatospecific bidirectional and autoregulatory tetracycline (Tet)-On system (Tet(bidir)Alb) ...

The antibacterial activity of two bisbenzylisoquinoline alkaloids, tetrandrine (Tet) and demethyltetrandrine (d-Tet), alone and in combination with the antibiotics ampicillin (AMP), azithromycin (AZM), cefazolin (CFZ) and levofloxacin (LEV) against 10 clinical isolates of staphylococcal chromosomal cassette mec (SCCmec) III type methicillin-resistant Staphylococcus aureus (MRSA) was studied. Su...

The aim of this study was to investigate the prevalence and transferability of resistance in tetracycline-resistant Escherichia coli isolates recovered from beef cattle in South Korea. A total of 155 E. coli isolates were collected from feces in South Korea, and 146 were confirmed to be resistant to tetracycline. The tetracycline resistance gene tet(A) (46.5%) was the most prevalent, followed b...

Two hundred twenty group D streptococci isolated from 1953 to 1954 from patients in the Washington, D.C., area were characterized. All were susceptible to ampicillin, vancomycin, and gentamicin; none produced beta-lactamase activity. High-level resistance to streptomycin was expressed by 117 strains, and 2 strains were resistant to >8 microg of chloramphenicol per ml. Three isolates were resist...

Tet(L) and Tet(K) are specific antibiotic-resistance determinants. They catalyze efflux of a tetracycline(Tc)-divalent metal complex in exchange for protons, as do other Tet efflux proteins. These Tet proteins also catalyze Na+ and K+ exchange for protons. Each of the "cytoplasmic substrates", Na+, K+ and the Tc-metal ion complex, can also be exchanged for K+, a catalytic mode that accounts for...

OBJECTIVES To analyse the sequence diversity of the tetracycline resistance gene tet(M) in Staphylococcus aureus from humans and animals and to determine mobile elements associated with tet(M) in S. aureus. METHODS In total, 205 tetracycline-resistant isolates were screened for tet(M) by PCR. tet(M) genes were sequenced and compared with tet(M) deposited in GenBank. Based on phylogenetic anal...