T7 promoters and expression

Laura K. Moen LKM100F at ODUVM.CC.ODU.EDU
Tue Jun 7 17:15:31 EST 1994

Hi, Netters!
   We have been struggling with expression of a protein with some toxic
effects on E. coli (not surprising considering its function), and we
chose the pRSET vector from Invitrogen because it uses the T7 promoter,
a system I equated with reasonably good control and good expression upon
induction.  We induce expression with infection by M13 carrying T7 polymerase.
So, we have found that the control of this system isn't so good - we have
a detectable level of expression in uninduced cells which isn't so good
because it does make the cells sickly.  Has anyone else experienced such
difficulties with T7 promoters?  I am surprised, but I am not exactly the
most experienced individual with protein expression.  Does anyone have any
suggestions for ways to suppress the background expression in our uninduced
cells?  We have tried using JM109 and XL-1 Blue cells - similar problems in
either line.  Thanks for any help/commiseration.  Laura Moen  Email or post
is OK.  Email address: LKM100F at ODUVM.cc.odu.edu  (U.S.)

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