Expression of toxic protein

Chen Ho An chen at
Thu Jan 29 12:00:44 EST 1998

There will always be problems if your protein is highly toxic because
the cells may die before it produces the protein in any significant
Tightly controlled expression may be one possibility- I've read of one
method whereby the orientation of the  gene is reversed but returned 
to correct orientation just before induction, or try induction by phage 
(i.e method is which the gene in transcribed only by T7 polymerase and
the T7 polymerase is provided by the phage).
Other methods (which I think is probably better) is to remove the gene
product once it is translated e.g. target it to periplasmic space
(though the yield will probably be low) or deliberately drive it into
inclusion body (the protein must however be able to be refolded). A
reference for the last one :
Jansson et al  Journal of Biomolecular NMR 7 (96) 131-141

Another useful reference is
  Miroux & Walker, Journal of Molecular Biology (96) 260, 289-298

Here the method is to select for mutants that can tolerate the toxic
gene product and showed that it is possible to express many toxic
proteins to very high level in E. coli.


HA Chen				tel: 0171 391 1354
Department of Biochemistry	chen at
University College London
Gower Street
London WC1E 6BT

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