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Characterization of the degron system !

In between the two jamborees, we finished the construction of our TirI degron system and had the time to test it once in Xenupus. Unfortunately the results were negatives. They are presented in this page.

Preparation of the RNAs

Starting from the gene, cloned into pSC1C3 for TirI or pSC2+ for GFP-AID, we amplified them with a sp6 promoter on the front of the gene and PCR purified. The mRNAs were then prepared from the PCR product using the Sp6 phage RNA polymerase. The RNAs were then precipitated and poly-adenilated with a RNA poly-adelylase. The mRNA were then treated with a mix of capping proteins before being injected.

The RNAs of TirI and GPD-AID were then pooled in equimolar ratio before being injected for the GFP-AID TirI.

GFP-AID - Pep2A - TirI in pCS2+

The two genes GFP-AID and TirI were fused with a Pep2A peptide, to be transcribed as a single protein. The Pep2A sequence comes from the Thosea asigna virus 2A, creating a peptide bridge in between two proteins. When the ribosome transcribe this sequence protein, one of the amino-acids bound formation is not catalyzed, giving birth to two distinct protein. This is a common method to design polysistronic mRNA in eukaryotes. It is also especially relevant system to use here, because it gives a one to one protein ratio, that we wanted to achieve to make sure the GFP will be properly degraded in the presence of auxin.