How to aleviate toxicity?

Chris LaRosa plarosa1 at
Sat Sep 25 08:45:48 EST 1999

Grow cells at 30 degrees instead of 37. this might help.
The Qiagen PQE vector system has a strain with very strong repression of
lac operon due to placement of the repressor gene on a high copy
plasmid..     Try different host strains.

Tracie Matsumoto wrote:

> Dear all,
> I am trying to clone a membrane protein in both a pBluescript and a
> yeast expression vector. However, although I can have it done with the
> unmodified sequence, every time I try to modify it (for example, by
> adding a tag for immunolocalisation) I get funny plasmids, none at all
> or no transformation of E. coli cells. This looks to me as toxicity
> (similar proteins also have the same problem).
> Does anyone know of a way to reduce this problem when trying to
> transform a toxic protein into E. coli? I have heard of adding glucose
> to LB or to grow the bacteria at low temperatures but nobody could give
> details of these.
> Any help would be much appreciated.
> Please answer to my directly if possible. I can't check this newsgroups
> very often. Thanks!
> Agustin Hernandez
> e-mail: hernandez at

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