Toxic protein for E. coli (M15)

Bertrand Collet b.collet at abdn.ac.uk
Thu Sep 5 03:26:04 EST 2002


Dear all,

I am new to recombinant protein production and I am attempting to
produce a fish DNA-binding protein in E. coli.

I use the pQE30 expression vector in M15 bacterial strain.
I noticed that the growth rate of the bacterial cultures is the same
without inducer for pQE30 only and for pQE30 expressing my protein.
However, when I induce with IPTG (1mM) pQE30 continue to grow normally
but my expression plasmid culture grow very very slowly: It appears that
my protein is toxic for E. coli but that I do not have any leaking
expression.

Under these conditions, is there a good method to make E. coli produce a
toxic protein, or do I have to switch to
another expression system ?

I tried to reduce the level of expression (lower temperature 28 deg,
lower IPTG concentrations ... but no clear results so far).

Thanks in advance for any advises,


Bertrand Collet





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