RecA-minus cells for T7 expression

Emir ekhatipo at
Wed Oct 25 20:33:01 EST 2000

I would appreciate someone recommending me an E.coli RecA- strain that could
be used for lambda CE6 induction of expression from a pET (T7)-type
construct. BL21 (not DE3) fits the purposes of CE6 induction (see
Stratagene's CE6 induction manual), but it is RecA+. I don't perfectly
understand the details of what makes BL21 cells permissive for lambda
lysogeny, and it is difficult for me to figure out which of the conventional
RecA- strains (e.g., DH5alpha, HB101, JM109, XL-1 Blue) would allow
infection by the phage and insertion and expression of the T7 polymerase.
Thank you.

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