Team:TU Munich/Project/Constitutive Promoter

From 2012.igem.org

(Difference between revisions)
(General remarks and issues)
Line 28: Line 28:
==General remarks and issues==
==General remarks and issues==
----
----
-
[[File:Promoter strenghts .png|400px|thumb|right|Original image taken from <html><a href=""></a></html>. Comparison of promoter strength with GFP, cloned promoters are marked by arrows]]
+
[[File:Promoter strenghts .png|300px|thumb|right|Original image taken from <html>[<a href="http://http://www.ncbi.nlm.nih.gov/pubmed/22383307">Sun J. et al., 2012</a>]</html>. Comparison of promoter strength with GFP, cloned promoters are marked by arrows]]
For '''comparison of the promoter strength''' 3 timepoints were chosen. After '''12''' hours, after '''24''' hours and '''48''' hours. This way differences in activity due to varying Ethanol- and glucose concentrations can be analyzed.
For '''comparison of the promoter strength''' 3 timepoints were chosen. After '''12''' hours, after '''24''' hours and '''48''' hours. This way differences in activity due to varying Ethanol- and glucose concentrations can be analyzed.
This would be the more interesting since the influence of these substances on the activity of TEF2-Promoter has not been analyzed this far.
This would be the more interesting since the influence of these substances on the activity of TEF2-Promoter has not been analyzed this far.

Revision as of 19:31, 26 September 2012


Contents

Constitutive Promoters


Responsible: Georg Schützinger

For the expression of of proteins like limonene, thaumatin and others, promoters are essential. Since gyle from beer is a complex medium, the controlled induction of proteinexpression proves to be a nearly impossible task. Therefore constitutive promoters are the ideal solution for that problem. They offer simplicity, and therefore are the first choice for the introduction of new biosynthetic pathways in yeast in complex media.

In order to finetune biosynthetic pathways with two or more enzymes, like it is the case with caffeine synthases, we want to use 3 constitutive promoters ADH1, TEF1 and TEF2. Their strength, and constant expression have been characterized by [Partow et al., 2010, Sun J. et al., 2012] and many more. For illustration of their difference in strength TEF1-P and ADH1-P were cloned in front of Renilla Luciferase BBa_J52008 in pTUM100 BBa_K801001 and the bioluminescence was measured. The same experiment shall soon be also made with TEF2-P.

Background and principles


The promoter ADH1 is one of the most widely used constitutive promoters, for proteinexpression in yeast. It naturally controls the expression of Alcohole Dehydrogenase 1 of Saccharomyces Cerevisiae. This enzyme is part of the yeast glycolytic pathway and is needed for the fermentation of glucose into alcohole. For that reason its natural form (1500 bp) is inhibited by ethanol. To avoid this problem, we used a shortened version (720 bp) BBa_K319005 that was successfully engineered and tested by [Ruohonen et al., 1995] and that is not susceptible to ethanol repression, thus providing constant expression throughout the brewing process.

The promoter TEF1 controls the expression of translation elongaton factor EF1 alpha. The most important characteristics of this promoter for brewing is his high expression strength that is 5x above ADH1-P, and its insensitivity to repression by ethanol which often occurs with constitutive promoters from the yeast glycolytic pathway [Partow et al., 2010]. During the brewing process expression even becomes stronger due a slight repression by Glucose at the beginning.

The promoter TEF2 controls the expression of a second gene for translation elongation factor EF1 alpha. Since TEF2 proteine alone can keep mutants, lacking TEF1, growing, it is believed that it is an identical of nearly identical version of TEF1 proteine [Schiermaier et al., 1984].

General remarks and issues


Original image taken from [Sun J. et al., 2012]. Comparison of promoter strength with GFP, cloned promoters are marked by arrows

For comparison of the promoter strength 3 timepoints were chosen. After 12 hours, after 24 hours and 48 hours. This way differences in activity due to varying Ethanol- and glucose concentrations can be analyzed. This would be the more interesting since the influence of these substances on the activity of TEF2-Promoter has not been analyzed this far. If you set the activity of TEF1-Promoter for 100%, the activity of ADH1-P should be roughly 20% and keep constant. TEF1-Promoter should reach 150 % during the later The activity of TEF2-P activity should be 40% at the beginning.

Gel picture of finished Constructs

20120918 ADH1-P und P791.png

  • Analytical digestion of ADH1-P with luciferase in pTUM100

20120918 TEF1-P und P791.png

  • Analytical digestion of TEF1-P with luciferase in pTUM100

Biobricks

BBa_K801001 pTUM101 yeast shuttle vector with pTEF1 promoter

BBa_K801002 pTUM102 yeast shuttle vector with pTEF2 promoter

BBa_K801003 pTUM103 yeast shuttle vector with pADH1 promoter

BBa_K801010 TEF2 constitutive yeast promoter

BBa_K801011 TEF1 yeast terminator

BBa_K801012 ADH1 yeast terminator

Results of luciferase assay

References


  • [Da Silva et al., 2012] Da Silva, Nancy A.; Srikrishnan, Sneha (2012): Introduction and expression of genes for metabolic engineering applications in Saccharomyces cerevisiae. In: FEMS Yeast Res. 12 (2), S. 197–214.
  • [Sun J. et al., 2012] Sun, Jie; Shao, Zengyi; Zhao, Hua; Nair, Nikhil; Wen, Fei; Xu, Jian-He; Zhao, Huimin (2012): Cloning and characterization of a panel of constitutive promoters for applications in pathway engineering in Saccharomyces cerevisiae. In: Biotechnol. Bioeng. 109 (8), S. 2082–2092.
  • [Partow et al., 2010] Partow, Siavash; Siewers, Verena; Bjørn, Sara; Nielsen, Jens; Maury, Jérôme (2010): Characterization of different promoters for designing a new expression vector in Saccharomyces cerevisiae. In: Yeast 27 (11), S. 955–964.
  • [Schiermaier et al., 1984] Schirmaier, F.; Philippsen, P. (1984): Identification of two genes coding for the translation elongation factor EF-1 alpha of S. cerevisiae. In: EMBO J. 3 (13), S. 3311–3315.
  • [Ruohonen et al., 1995] Ruohonen, L.; Aalto, M. K.; Keränen, S. (1995): Modifications to the ADH1 promoter of Saccharomyces cerevisiae for efficient production of heterologous proteins. In: J. Biotechnol. 39 (3), S. 193–203.