Silent ClaI sites - info ?

vernon VERNON at za.ac.uct.micro
Thu Sep 23 08:02:38 EST 1993



In article <jjw-230993123321 at 150.203.39.67>, jjw at rsbs1.anu.edu.au (Jeremy Weinman) writes:
>Silent ClaI sites
>
>Does anybody out there in netland know of any info (published or otherwise)
>on why ClaI sometimes doesn't recognize a ClaI site?  We've got some clones
>which we have been mapping and we have a cla site that cuts on the basis of
>some unknown or perhaps archane variable, seemingly regardless of how well
>other cla sites in the clone are cutting.  Any thoughts?
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>Dr. Jeremy Weinman                              Email:
>jjw at rsbs1.anu.edu.au
>Plant Microbe Interaction Group                 Phone:  61 6 2495051
>Research School of Biological Sciences          Fax:    61 6 2490754
>Australian National University                  Snail:  PO Box 475,
>Canberra,
>                                                        ACT 2601, AUSTRALIA


When a dam methylation site (GATC) overlaps a ClaI site, then
the site will not cut, unless your DNA was prepared from a dam- E.coli
host.
(Not cut actually means cuts poorly or not at all depending upon the
DNA prep, probably due to how completely sites were methylated)


----------------------------------------------------------------------
 Michael Benedik                INTERNET: Benedik at uh.edu
 Dept. of Biochemical & Biophysical Sciences
 University of Houston              BITNET: Benedik at uhou
-----------------------------------------------------------------------


Does this apply exclusively to ClaI sites, or is there a list of
additional restriction enzymes which act in an analogous way?





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