How to circumvent DNA restriction in a bacterial host?

M. Alexeyev malexeyev at biost1.thi.tmc.edu
Tue Nov 21 20:28:39 EST 1995

In article
<Amy.Verhelst-2111951700070001 at host-181.subnet-12.med.umich.edu>,
Amy.Verhelst at mailgw.surg.med.umich.edu (Amy) wrote:

  You could also try methylating DNA in vitro
> with some available methylases (this would probably only work if type II
> endonuclease is responsible, and might call-in problems with dcm-type
> restriction)  Good luck!

Also keep in mind that there are over 100 different sequences known so far
that are recognized by type II R-M systems (and therefore, there are over
100 methylation patterns). Worse, in some extreme cases there are typeII
enzymes that recognize same sequence, but may or may not cut depending on
methylation pattern. For example, Sau3AI, MboI and DpnI do recognize the
same sequence GATC. However, Sau3AI would cut it regardless of methylation
of internal adenosine, MboI would cut only unmethylated sequence and DpnI
would cut only hemymethylated sequence (if I am not mistaken). Therefore,
you'll be much better off if you save your time and money (both methylases
and their cofactor S-adenosylmethionin are pretty expensive).

M. Alexeyev.

More information about the Microbio mailing list

Send comments to us at biosci-help [At] net.bio.net