Difference between revisions of "Part:BBa K1150021"

Krüppel-associated Box repressor domains - commonly termed as KRAB - are highly conserved polypeptide motifs and were first functionally characterized in 1991 (Rosati et al., 1991). As they constitute about one third of all human zinc finger transcription factors, key regulatory features in higher eukaryotic transcriptomics are suggested (Witzgall et al., 1994). Even in terms of tetrapod evolution, the role of their great abundance has been extensively discussed (Birtle, 2006). Even though KRAB minimal domains are usually no longer than 50-75 amino acids, their mechanism of function remains complex.

Common biochemical models suggest a key role in epigenetic silencing, by recruiting a scaffold of diverse proteins - amongst others histone deacetylases and histone methyltransferases (Urrutia, 2003). Til date in 2013, KRAB repressor domains were attached to several DNA binding proteins such as tetR, TAL effectors and dCas9 - thereby efficiently silencing gene expression downstream of desired target promoters.

In this attempt, an SV40 promoter was cloned in front of a RFC25-conformal dCas9. Flanked by two NLS, complemented with an HA-Tag for Western blot detections and fused to KRAB with a net 7 amino acid linker, this resulted in the here-shown composite part.

Theoretically, this functional repressor can be directed towards almost any gene or promoter of interest, by harnessing a specifically designed [http://2013.igem.org/Team:Freiburg/Project/crrna#rnaimer RNAimer plasmid]. Two 30-basepair oligos, corresponding to the desired target, must therefore be annealed and inserted into the RNAimer plasmid. Team Freiburg 2013 provides an easy [http://2013.igem.org/Team:Freiburg/Project/crrna#design_tool designing tool] for such an attempt. Furthermore, [http://2013.igem.org/Team:Freiburg/Project/crrna#multiple_targeting multiple transcriptional regulation] can be achieved by an idempotent cloning strategy, utilizing various crRNA plasmids and co-transfecting this final vector with dCas9-effectors.