Hi, I am trying to develop a biosensor in wildtype E coli and I want to know the expression level between varieties of inducible promoters, especially the induced vs non-induced state. This is because I cannot use T7 promoter for my biosensor and I also want the sensor to have low basal expression, but high expression when induced. I found papers that compare PBAD, T7 with trc, different paper than compare tac vs different version of tac, but I couldn't find papers that actually compare LacUV5, trc, tac and PBAD at the same time. If anyone could pinpoint papers or comments on the comparison between these promoter, I will be very thankful.
Article BglBrick vectors and datasheets: A synthetic biology platfor...
Additional file 1 from this paper might help you if you compare vectors with similar replicons and FPs. In my experience pBAD and pTet have the best repression followed by pLac(wt or UV5). ptac, ptrc and T7 are very strong but very leaky. T5-lac is leaky and not even strong.
Bujard's lab did extensive analysis of promoter strength in the late 1980s Knaus & Bujard 1988 EMBOJ 7:2919-2923. Kammerer et al 1986 EMBOJ 5:2995-3000. If your experimental conditions can tolerate it, phage lambda PL regulated by cI857 lambda repressor gives good regulation and high level expression. A ts lambda repressor works at 30 and not at 42 so shift from 30 to 42 and hold on to your hat.
You might consider whether you really need that high level expression for your biosensor experiments. The pBAD promoter (and pTet) does give very tight regulation and although it isn't the strongest in terms of transcription levels, with a high copy plasmid you are likely to get more than adequate expression. You really need the strong promoters when you are going for protein production but you may not need that much for your situation.
Mark Kainz suggestion of using lambda promoters is also good, there are vectors based both on PL and PR using a ts repressor. To some degree it also comes down to how you wish to induce. Adding IPTG or arabinose is easy. Doing a temperature shift is fine at small volumes but trickier at larger volumes. The trp promoter itself is also quite tightly regulated and strong, but you need to do a media shift where you go from Tryptophan containing media to media without tryptophan, so usually most people don't bother with this.
- Badges
- Science topic
- Similar topics
- Papers