finiding the best promoter for induction od toxic protein - protein expression (Mar/05/2007 )

Hi everyone,
i'm trying to express a 44KD protein which is a polymer (4 tandem repeat of the same 11KD protein) in BL21 Ecoli. till now we worked with PET45 (Lac operon and T7 promoter), the 44KD protein is toxic to the Ecoli and therefore the Ecoli throw in away with recombination (we tried expressing with rac- but the yield of bacteria was poor)
i have heard that the ara promoter and tet promoter are better for induction od toxic protein, i would like to know if it is true and way
thanks allot

If you're already working with pET, try using BL21(DE3) with pLys E. The RNA pol gene is in the reverse orientation, and has all sorts of checks on its own expression. Try growing to high OD before induction, and only induce for a short time.
Alternately, if nothing works, you might have to use an intein expression system. Just google it and you should come up with the details.