Biomolecular Breadboards:Preliminary Data

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Preliminary Data

Plasmid Expression of GFP

Using pBEST-OR2-OR1-Pr-UTR1-deGFP-T500, a plasmid enhanced for GFP expression, the biomolecular breadboard is able to express mass at equal concentrations to comparable bacteriophage in-vitro systems (J. Shin and V. Noireaux, 2010).

Expression of plasmids can be optimized by concentration.

Plasmid sat.png

  • Raw data file: plasmid_deGFP-070812.xls (Excel spreadsheet)
  • Information about protocol on "Outline" sheet; plotted data is on the sheet "plotted-data"


Figure 1. eGFP expression as a function of plasmid DNA template. Plasmid DNA pBEST-OR2-OR1-Pr-UTR1-eGFP-T500 is varied by concentration.

Protecting Linear DNA from Exonuclease-Mediated Degradation

Current standards for circuit design utilize plasmids for DNA template, which require time-consuming subcloning steps. However, circuits based on linear DNA require only PCR assembly or gene synthesis, which drastically decreases preparation time. As a purely extract-derived system, our biomolecular breadboard exhibits exonuclease activity which degrades linear DNA. We are developing multiple technologies to protect linear DNA from exonuclease degradation. These include:

  1. Protecting linear DNA using noncoding segments
  2. Inhibiting RecBCD exonuclease with gamS
  3. Adding thiosulfate bonds to 5' ends

Protection Sequences

Linear.png
Figure 2: Exonuclease protection using non-coding DNA. Linear DNA templates, 2nM, are derived from plasmid DNA pBEST-OR2-OR1-Pr-UTR1-eGFP-Del6-229-T500 with varying amounts of noncoding DNA surrounding the coding sequence.

GamS

GamSComp.png GamS-protsynt81bis 05Sep12.png
Figure 3. (left) GamS from lambda phage, an inhibitor of RecBCD complex, inhibits template DNA degradation. Linear DNA templates, 2nM, are derived from plasmid DNA pBEST-OR2-OR1-Pr-UTR1-eGFP-Del6-229-T500. GamS supplied at 3uM concentration. (right) Simulation results based on a simple ODE model.



Linear sat.png
Figure 4. eGFP expression as a function of linear DNA template, with gamS. Plasmid DNA pBEST-OR2-OR1-Pr-UTR1-eGFP-Del6-229-T500 is varied by concentration. GamS supplied at 3uM concentration.

Thiosulfate Bonds

Ts-1.png
Figure 5. Thiosulfate bonds protect against 5' exonuclease degradation. Linear DNA templates, 2nM, are derived from plasmid DNA pBEST-OR2-OR1-Pr-UTR1-eGFP-Del6-229-T500. 5 thiosulfate bonds are present at each 5' end. GamS supplied at 3uM concentration.