CRISPRi is not strand-specific at all loci and redefines the transcriptional landscape.

Howe FS., Russell A., Lamstaes AR., El-Sagheer A., Nair A., Brown T., Mellor J.

CRISPRi, an adapted CRISPR-Cas9 system, is proposed to act as a strand-specific roadblock to repress transcription in eukaryotic cells using guide RNAs (sgRNAs) to target catalytically inactive Cas9 (dCas9) and offers an alternative to genetic interventions for studying pervasive antisense transcription. Here, we successfully use click chemistry to construct DNA templates for sgRNA expression and show, rather than acting simply as a roadblock, sgRNA/dCas9 binding creates an environment that is permissive for transcription initiation/termination, thus generating novel sense and antisense transcripts. At HMS2 in Saccharomyces cerevisiae, sgRNA/dCas9 targeting to the non-template strand for antisense transcription results in antisense transcription termination, premature termination of a proportion of sense transcripts and initiation of a novel antisense transcript downstream of the sgRNA/dCas9-binding site. This redefinition of the transcriptional landscape by CRISPRi demonstrates that it is not strand-specific and highlights the controls and locus understanding required to properly interpret results from CRISPRi interventions.

DOI

10.7554/eLife.29878

Type

Journal article

Journal

Elife

Publication Date

23/10/2017

Volume

6

Keywords

CRISPRi, HMS2 and GAL1, S. cerevisiae, chromosomes, genes, strand-specificity, transcription initiation, transcription roadblock, transcription termination, Bacterial Proteins, CRISPR-Associated Protein 9, DNA, Fungal, Endonucleases, Protein Binding, RNA, Guide, Saccharomyces cerevisiae, Transcription, Genetic

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