Hi, I am wondering the difference between bacterial cell E. coli WK6 and other cells, like E. coli (BL21)? There are several cases using the bacterial cell E. coli WK6 to express some crystallization chaperone proteins. Could I use the routine expression cells like the BL21(DE3),Rosetta(DE3) to replace it?
WK6 is a pretty standard E. coli K12 strain (genotype is F' lacIq delta(lacZ)M15 proA+B+ delta(lacproAB) galE rpsL). So it can be used for cloning and will do blue/white selection but is not R- so not good to transform with foreign DNA (DNA not propagated in E. coli). It is not designed as a particular expression strain but grows well and is likely to express proteins reasonably.
However your choice of strains is going to depend upon your expression system. If you are using an expression plasmid with a T7 promoter (like a pET plasmid) then you should NOT use WK6, it will not work. You need a strain carrying T7 polymerase (like BL21(DE3). The DE3 designation means the strain is lysogenic for a phage carrying the T7 polymerase gene. On the other hand, if you are using an expression plasmid that is not a pET plasmid and does not use a T7 promoter, then you should not use a (DE3). Expression of the T7 polymerase could be deleterious to your expression.
Note that BL21 is deficient in some proteases, so that would stabilize expression of some proteins. Rosettta has entirely other properties and is designed for expression of genes that have a number of rarely used codons in E. coli.
The short answer is that you need to pick the appropriate strain depending upon the expression system you are using, the level of expression you need, whether your protein is problematic to express in E. coli or not, and whether you need other facilitating proteins or factors. Your question does not provide enough information to be able to make a recommendation.
Hi
non-pathogenic experience E.coli was used in our experince. experience. as E.coli has flagela and can swim by it, and it is well known as a water and wastewater indicator, we chose it.
Thanks a lot for Michael J. Benedik's professional comments. Yes, I am planning to use the expression plasmid pET with a T7 promoter. Then it is not approporiate to use the WK6 strain to expression recombinant proteins with T7 promotor, I'll try to run small scale test with several BL21 strains with the DE3 lysogen, then choose an idea one for production.
I do not know what is special. I attached it. It requires expression in WK6. My email is [email protected]
E. coli WK6 is good for the production of nanobody proteins that have a disulfide bond and likely from inclusion body in the cytoplasm. So this strain helps some proteins fold correctly in the periplasm (particularly for disulfide bond formation ) due to the DsbC enzyme and more oxidative environment. Other strains such as Shuffle T7 might work too.
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