Coli strain for periplasmic expression

[Michael Benedik]

In article <2ma1ip$lr0 at lyra.csx.cam.ac.uk>, dh124 at mole.bio.cam.ac.uk (Deborah Hodges (Rheumatol)) writes:
>Hi,
>	I am using the vector pASK-60 to express a heavily disulphide bonded
>protein in E.Coli. It uses the ompA signal sequence to target the protein to
>the periplasm. I've managed to get the thing to express but the yield
>is tiny. Admittedly I haven't tinkered with the medium but the cells, 
>(XL-Blues) seem to get very fragile as they express and I get cytoplasmic
>contamination of my periplasm preps.
>	My question is : Does anyone know of a Coli strain that would give
>me a better yield?
>	Thanks in advance
>		Debbie
>
>-- 
>-------------------------------- ---------------------------------------     
>Debbie Hodges			|
>dh124 at mole.bio.cam.ac.uk	|	There's always something to eat 
>E6 Addenbrookes Cambridge UK	|	when you've got dwarf bread.


The first thing I would try is to get away from a recA mutant strain
and use a rec+ strain. With a RecA- about 50% of the cells are dead or
dying. Try JM101 or something similar if you need lacIq around, other
wise any rec+ strain.

----------------------------------------------------------------------
 Michael Benedik				INTERNET: Benedik at uh.edu
 Dept. of Biochemical & Biophysical Sciences	
 University of Houston				BITNET: Benedik at uhou
-----------------------------------------------------------------------