The tetracycline efflux protein encoded by the tet(K) gene from Staphylococcus aureus is a metal-tetracycline/H+ antiporter.
The tet(K) gene from Staphylococcus aureus was highly expressed in Escherichia coli by an alteration of its initiation codon from TTG to ATG and its ribosome-binding sequence from GAGG to GGAGG [Noguchi, N. et al. (1994) Biol. Pharm. Bull. 17, 352-355]. The inverted membrane vesicles prepared from the tet(K)-expressing cells showed respiration-dependent [3H]tetracycline transport comparable to the vesicles from the tet(B)-expressing cells. The affinity of Tet(K) vesicles to tetracycline was the same as that of Tet(B) vesicles, whereas the former Vmax value was about 60% of the latter one. Contrary to Tet(B) vesicles, Tet(K) vesicles showed no significant minocycline uptake, which was consistent with the low minocycline resistance of the Tet(K)-producing cells. The tetracycline transport mediated by Tet(K) vesicles was coupled with proton transport and the translocation of 60Co2+ ions as well as in Tet(B) vesicles. This observation indicates that the class K tetracycline resistance determinant from Gram-positive bacteria also encodes a metal-tetracycline/H+ antiporter that is functionally similar to that encoded by tet(B), although there is a considerable difference in the primary sequences and the putative topologies of these Tet proteins.
Yamaguchi
A
A
Division of Microbial Chemistry, Faculty of Pharmaceutical Sciences, Chiba University, Japan.
Shiina
Y
Y
Fujihira
E
E
Sawai
T
T
Noguchi
N
N
Sasatsu
M
M
D017920:Antiporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003035:Cobalt / Q000378:metabolism; D004926:Escherichia coli; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008911:Minocycline / Q000378:metabolism; D011522:Protons; D011994:Recombinant Proteins / Q000378:metabolism; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism*; D013752:Tetracycline / Q000378:metabolism*; D013753:Tetracycline Resistance / Q000235:genetics*
D017920:Antiporters; D001426:Bacterial Proteins; D008565:Membrane Proteins; D011522:Protons; D011994:Recombinant Proteins; C084212:tet(K) protein, Staphylococcus aureus; C079051:tetA protein, Bacteria; D003035:Cobalt; D013752:Tetracycline; D008911:Minocycline