M13 glucose repression

ijiwaru at wheel.dcn.davis.ca.us ijiwaru at wheel.dcn.davis.ca.us
Mon Mar 31 14:09:13 EST 1997


Some months ago, actually quite a long time ago, someone on this group
asked about glucose repression of M13.  We think we sort of have an answer
although we haven't actually done the experiment to test our theory. 
First, I have to say we've been in contact with someone who works with
wild-type M13 and says they don't see any such repression.  We've seen it,
but we've been using M13mp18 or similar derivatives.  If you look at the
map for M13mp18, it turns out that the Plac and control points are just
upstream and in the same direction as the promoter for pII and pX, both of
which are essential for replication.  We think that when you try to shut
down expression from Plac with glucose, you also create a polar effect,
essentially shutting down pII and pX production.  We think we can test
this by growing a KanR M13mp18 derivative in cells on plates +/- glucose. 
If replication is inhibited like we think it is, then we don't expect to
see very big colonies, or any colonies on Kan plates.

Lyle Najita
CEPRAP
University of California - Davis



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