BL21(DE3) and trc promoter

Dr. Duncan Clark Duncan at
Tue Feb 8 07:44:20 EST 2000

In article <Pine.GSO.4.21.0002081427230.4046-100000 at>, Petri
Kursula <pkursula at> writes
>Confused by all these E.coli genotypes and strains, I would like to know
>if anyone has used BL21(DE3) cells to produce recombinant proteins from a
>vector with the trc promoter, such as pTrc99a. If yes, is this expression
>tightly regulatable by IPTG, or do you get leaky expression?

Probably leaky unless you have a copy of lacI on your vector in order to
make sure you really have enough repressor to switch the trc off.

If you really need tight control maybe an arabinose promoter expression
vector would be better (available from Invitrogen).

The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Duncan Clark
DNAmp Ltd.
Tel: +44(0)1252376288
FAX: +44(0)8701640382

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