Dam methylation and BclI

Michael Lichten lichten at helix.nih.gov
Thu Feb 19 09:35:20 EST 1998

The dam and dcm methylation systems of E. coli have no corresponding
restriction systems.  You can freely move DNA from dam+ to dam- and vica
versa, and the same for dcm.  You might want to think about how the folks
at stratagene constructed their strains, in the first place!

In article <slrn6eofna.693.aiyar at ebv.oncology.wisc.edu>,
aiyar at ebv.oncology.wisc.edu wrote:

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

Michael Lichten
lichten at helix.nih.gov
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