Dam methylation and BclI

Ashok Aiyar aiyar at ebv.oncology.wisc.edu
Thu Feb 19 09:17:14 EST 1998

On Thu, 19 Feb 1998 10:23:25 +0000,
Per Mygind (perm at medmicro.aau.dk) wrote:
>I recently purchased E.coli scs110 stratagene in order to circumvent the
>sensitivity of BclI to dam methylation. The strain worked perfect (as
>opposed to JM110). My question is, however, what happens if you try to
>transform this DNA into a host which is DAM positive - will the dna be
>degraded, resulting in no transformants ?

Most common laboratory strains of E. coli are restriction(-),
modification(+) (r-m+), indicating that they will modify DNA (methylate
it) but not degrade it.  I have transformed ligations of dam(-) DNA
into dam(+) strains on a number of occasions without problems.

Ashok Aiyar, Ph.D.
McArdle Laboratory for Cancer Research
aiyar at ebv.oncology.wisc.edu

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