Toxic fragment in pBR322

[Bernard Murray]

In article <320EF86E.5C9A at uibk.ac.at>, stephan.geley at uibk.ac.at says...
>
>What is the so-called "toxic fragment" in plasmid pBR322?

The reference I see quoted most often is;
Lusky, M. & Botchan, M. (1981) Nature 293, 79

I must confess I haven't read this so I know neither the
location of the guilty sequence nor the mechanism for the
poisoning but I seem to recall that the worst manifestation
was with vectors containing SV40ori in that they were unable
to replicate correctly in permissive cells.  I am grateful
for the people that recognised this and allowed the sequences
to be removed from most/all modern eukaryotic expression
vectors.
	I hope that this is of some help,
			Bernard

Bernard Murray, Ph.D.
bernard at elsie.nci.nih.gov  (National Cancer Institute, NIH, Bethesda MD, USA)