From owner-cellbiol@net.bio.net Tue Feb 25 22:00:00 1997 Path: biosci!rutgers.rutgers.edu!gatech!csulb.edu!news.sgi.com!howland.erols.net!surfnet.nl!swidir.switch.ch!swsbe6.switch.ch!news-zh.switch.ch!bromo.switch.ch!scsing.switch.ch!rzunews.unizh.ch!NewsWatcher!user From: zjons@vetbio.unizh.ch (Zophonias O. Jonsson) Newsgroups: bionet.microbiology,bionet.molbio.proteins,bionet.cellbiol Subject: Re: Temperature control in the T7 RNA polymerase/promoter system. (For protein expression)? Date: Wed, 26 Feb 1997 16:31:16 +0100 Organization: Universitat Zurich-Irchel Lines: 29 Message-ID: References: <5f0jic$1ete$1@snunews.snu.ac.kr> NNTP-Posting-Host: 130.60.120.18 Xref: biosci bionet.microbiology:9092 bionet.molbio.proteins:10104 bionet.cellbiol:6771 In article <5f0jic$1ete$1@snunews.snu.ac.kr>, newera@plaza.snu.ac.kr () wrote: > Why is the temperature control for growing E. coli under the T7 RNA > polymerase/promoter system required? Generally one does not have to play around much with temperature when expressing proteins using the T7 promoter system. Sometimes one can increase yields of soluble protein by inducing at low temperatures and sometimes problems with toxicity can be alleviated, but in general growth and induction at 30 or 37*C is sufficient for most proteins. The protocol you describe sounds like a special case. You did not mention what E.coli strain was used as host. If it is a normal DE3 lysogen, where the T7 RNApol is controlled by a Lac promoter, this temperature juggling is very strange. If, on the other hand, the expression strain contains the T7 pol under the control of a heat inducible promoter (such as lambda PL in a strain with temperature-inducible cI repressor), this wold make sense. I have never heard of such a beast, however. If it exists it might be interesting ! Zophonias _____________________________________________________________________ Zophonias O. Jonsson Institut fur Veterinarbiochemie Tel: (41-1)-257-54-75 Universitat Zurich-Irchel Fax: (41-1)-362-05-01 Winterthurerstrasse 190 CH-8057 Zurich Switzerland _____________________________________________________________________ .