rak at sun1.ruf.uni-freiburg.de
Fri Dec 13 13:21:36 EST 1991
BI1RGW at IBM.SHEFFIELD.AC.UK writes:
>The tetracycline resistance gene on pBR322 and that on transposon Tn10 are
>different, so (clearly) there are at least 2 different resistance genes.
>It is possible to select against tet-resistance due to Tn10 using
>Fusaric Acid and ZnCl2, using heat-denatured chlortetracycline to induce
>the resistance. This procedure works because of a reduction in the
>membrane's permeability to Tet, which makes the membrane *more* permeable
>to Fusaric Acid.
>BUT, this selection doesn't work against pBR322. So, presumably, the tet
>resistance on pBR322 doesn't work in the same way.
>Hope this is of some help,
>Robin Walters Robert Hill Institute,
> Dept. of Mol. Biol. & Biotech,
>BI1RGW at IBM.SHEF.AC.UK Univ. of Sheffield,
I haven't seen the original posting and therefore do not know
the original question. I would, however, like to correct
Robin Walters. The method to select against tet resistance has been
described in: Bochner, Huang, Schieven and Ames (1980) J. Bact.
9143:926-933. The authors found that it works nicely against pBR322
and its derivatives. We can confirm this. We use the method (which
is known as the "Bochner" selection) routinely and with good success
to cure E.coli from pBR322. Of course we don't add chlortetracycline
because the tet resistance gene of pBR322 is expressed constitutively.
As far as I know the mechanism of the Bochner selection is still unclear.
For a discussion of the possible mechanism see the paper cited above.
Hope this is of additional help :)
Bodo Rak | Internet: rak at sun1.ruf.uni-freiburg.de
Dept. of Biology III (Genetics) | BitNet: rak at dfrruf1
University | Phone: +49 761 203 2729
D-7800 Freiburg / Germany | Fax: +49 761 203 2745
Bodo Rak,203-2729 <rak at sun1.ruf.uni-freiburg.de>
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