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Team:Brasil-SP/Results/CharacterizationAssemblies
From 2014.igem.org
Results: After the incubation period of the transformed E. coli a large portion of the colonies were glowing green. So the promoter does work. Moreover, this biobrick works on E. coli despite the fact it was designed for B. subtilis. |
Promoter BBa_K143015
Question: How does the transcription caused by this promoter varies with the IPTG induction?
DI circuit
KV Characterization
This construction is a simple assembly of the of the Lac promoter BBa_K143015 and the GFP BBa_E0840. The Plac was synthesized by our team using PCR (check out the PCR for Synthesis Protocol). Since there is no LacI being produce, apart from the low levels the e. coli does, the output expected is a significant GFP fluorescence. The result obtained corresponded matched our expectations as shown in the graph above.
Tunning of the QteE Threshold
Question:What are the concentration of QteE needed to hamper the LasR induction of the promoter PlasR?
This is the most difficult task of our project. Tunning the production of QteE so that we establish the correct threshold for the discretization of the Cystatin C level in serum. To attack this challenge we designed 3 circuits so that we could plot a calibration curve. In this circuits we put the transcription of the LasR and QteE under two differnt promoters, the Pveg (BBa_K823003) and PlasR (BBa_K143015).
What we expected to see
DI: Here we expected no flourescence at all since the PcomE promoter would have no phosphorilated ComE to activate LasR expression.
KX: In this construction LasR was being producessed constitutively while there was no QteE expression. Because of that the LasR would be able to induce the GFP expression with no expression barrier.
KXIV: This circuit has both LasR and QteE being generated at the same rate, that's because they are under the control of the same promter. What we wanted to verify was wheter the LasR could induce GFP expression whem in the same molar concentration as QteE.
KX Characterization
Besides we have obtained a low number of fluorescence cells their fluorescence was expressive. The low rate of fluorescence cells might be related to antibiotic problems. It would cause the bacteria do not replicate the plasmid with the assembly because it became nonessestial and hence, only few bacteria expressed GFP.
KXIV Characterization
In this assembly, LasR e QteE are constitutive and we expected to use it as a control for an equivalent assembly in which QteE is not under control of a constitutive promoter but an inducible promoter designed for high expression in Bacillus subtilis (BBa_K143015).
We displayed data in logarithmic scale, then geometric mean is generally chosen to analysis. As we expected, KX GFP expression levels were higher, as follows
Observation:There is no control displayed in the graph above because geometric mean is zero as there is no fluorescence in FL1-H, only autofluorescence.
References
SPIDLEN, J. et al. Data File Standard for Flow Cytometry, Version FCS 3.1. Cytometry Part A, v. 77A, n. 1, p. 97-100, Jan 2010. ISSN 1552-4922. Disponível em: <
