View source for Part:BBa K1923007


__NOTOC__
<partinfo>BBa_K1923007 short</partinfo>

This composite part is a fusion protein composed of GAL4, triple FLAG tag, two SV40 nuclear localization sequence,dCas9 and GFP. Triple FLAG tag and GFP is designed for observation and expression detection. The protein produced by this parts can be sequestered in the cytoplasm with the help of sgRNA and PAMmer, utilizing dCas9's mRNA binding ability. However, when there is a mutation in the target sequence of the mRNA, sv40 NLS would drag this protein into the nuclear. Then GAL4 would active the gene downstream UAS promoter. Thus this parts can be used for gene mutation surveillance <sup>[1]</sup>. 

In order to test that this construct is indeed functional, we performed a nuclear relocalization assay where we essentially compared the difference in the distribution of dCas9 with fused GFP in the yeasts. We transformed either dCas9 alone or dCas9 with sgActin expressing plasmid or dCas9 with both sgActin expressing plasmid as well as PAMmer into the yeast, and observed GFP signal under a fluorescence microscopy. As is indicated in Figure 1. Relocalization into the cytoplasm of suvCas9 proteins can be orchestrated by single guide RNAs targeting the Actin message (sgActin) and PAMmers. Specifically, in the presence of suvCas9s alone, GFP signal (indicating suvCas9) can only be observed in the nucleus, indicating an enrichment of nuclear localization of suvCas9s. However, when small guide RNA targeting the Actin message (sgActin) is co-expressed with suvCas9, GFP signal is relocated into the cytoplasm. In contrast, after introducing PAMmers, which function as single-stranded DNA mimics, the majority of suvCas9 proteins can now be stably sequestered in the cytoplasm. 

<div style="margin-left:120px;height:50%;width:50%;">
<img src="https://static.igem.org/mediawiki/2016/1/10/T--Tsinghua--project_figure1.png">
</div>

<strong>Reference:</strong>
<br>
[1] Nelles D A, Fang M Y, O’Connell M R, et al. Programmable RNA tracking in live cells with CRISPR/Cas9[J]. Cell, 2016, 165(2): 488-496.

<!-- Add more about the biology of this part here
===Usage and Biology===

<!-- -->
<span class='h3bb'>Sequence and Features</span>
<partinfo>BBa_K1923007 SequenceAndFeatures</partinfo>


<!-- Uncomment this to enable Functional Parameter display 
===Functional Parameters===
<partinfo>BBa_K1923007 parameters</partinfo>
<!-- -->