Difference between revisions of "Part:BBa K1935019"

Revision as of 15:24, 14 October 2016

dead Cas9 (dCas9)

Due to the unique ability of Cas9 to bind to essentially any complement sequence in any genome, researchers wanted to use this enzyme to repress transcription of various genomic loci. To accomplish this, the two crucial catalytic residues of the RuvC and HNH domain can be mutated to alanine abolishing all endonuclease activity of Cas9. The resulting protein coined dead Cas9, can still tightly bind to dsDNA. The interaction of dCas9 with target dsDNA is so tight that high molarity urea protein denaturant can not fully dissociate the dCas9 RNA-protein complex from dsDNA target.[23] dCas9 has been targeted with engineered single guide RNAs to transcription initiation sites of any loci where dCas9 can compete with RNA polymerase at promoters to halt transcription. Also, dCas9 can be targeted to the coding region of loci such that inhibition of RNA Polymerase occurs during the elongation phase of transcription. In Eukaryotes, silencing of gene expression can be extented by targeting dCas9 to enhancer sequences, where dCas9 can block assembly of transcription factors leading to silencing of specific gene expression.

Sequence and Features