tet resistance

BI1RGW at IBM.SHEFFIELD.AC.UK BI1RGW at IBM.SHEFFIELD.AC.UK
Tue Dec 17 08:53:39 EST 1991


rak at de.freiburg.ruf.sun1 writes:

"the method to select against tet resistance has been described in:
Bochner, Huang, Schieven and Ames (1980) 9143:926-933 [BTW this should
be vol. 143 not 9143 :-)]. This authors found that it works nicely
against pBR322 and its derivatives."

This method was originally developed for use with Salmonella
typhimurium, and was subsequently modified by Maloy & Nunn (1981) J Bact
145:1110-1112 for use with E. coli. I have only used this version of the
method, and so cannot speak for the efficacy of the Buchner method.
However, in my hands this was a poor selection against tet resistance
borne on pBR322.

Of course, this disparity could be entirely due to the
differences between the two recipes. My recollection is (without
unearthing the paper) that the Maloy & Nunn version was geared
specifically to selecting against Tn10, and may not be optimised for
selecting against the much higher levels of expression seen in cells
carrying pBR322.

To return to the original question (how many different tet resistances,
and what are their mechanisms?), the resistance genes on pBR322 and Tn10
seem (from the maps of the two elements that I have to hand) to be
different sizes, and have very different restriction maps. Maloy & Nunn
discuss the possible mechanism of the Tn10 resistance, and were the
source for my original posting. If pBR322 is also subject to fusaric
acid selection, then (presumably) it works by the same or a similar
mechanism.

Hope this is of yet further help :-)

Robin Walters
BI1RGW at IBM.SHEF.AC.UK



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