A strain that provides unmethylated lambdaZAP DNA ?

Casper Linnestad CASPERL at BIOMED.UIO.NO
Thu Jan 6 10:39:19 EST 1994

I am working on a barley gene promoter and want to make several constructs
(in pBluescript) containing different promoter fragments hooked up to Gus-Nos.

My barley gene is cloned in lambda ZAP and the DNA prep is methylated as we used
BB4 cells.

In the subcloning it would be very handy to use BclI (dam sensitive) and to my 
knowledge there are no dam insensitive isoschizomers of BclI.

In this particular case it is pretty difficult to PCR the required promoter
part(s) in order to get unmethylated DNA.

The only E. coli strain I can think of to solve my problem is ED8767 which is 
rec negative, met negative, and permissive of ambermutated lambda.
Any other suggestions or interesting E.coli strains out there?



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