Multiplexed Guide RNA Expression Leads to Increased Mutation Frequency in Targeted Window Using a CRISPR-Guided Error-Prone DNA Polymerase in Saccharomyces cerevisiae

• Clustered regularly interspaced short palindromic repeats(CRISPR)-Cas9technology, with its ability to target a specific DNA locus usingguide RNAs (gRNAs), is particularly suited for targeted mutagenesis.The targeted diversification of nucleotides in Saccharomycescerevisiae using a CRISPR-guided error-prone DNA polymerase calledyEvolvR was recently reported. Here, we investigate the effectof multiplexed expression of gRNAs flanking a short stretch of DNAon reversion and mutation frequencies using yEvolvR. Phenotypic assaysdemonstrate that higher reversion frequencies are observed when expressingmultiple gRNAs simultaneously. Next generation sequencing revealsa synergistic effect of multiple gRNAs on mutation frequencies, whichis more pronounced in a mutant with a partially defective DNA mismatchrepair system. Additionally, we characterize a galactose-inducibleyEvolvR, which enables temporal control of mutagenesis. This studydemonstrates that multiplex expression of gRNAs and induction of mutagenesisgreatly improves the capabilities of yEvolvR for generation of geneticlibraries in vivo.

Subject headings

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Cell- och molekylärbiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Cell and Molecular Biology (hsv//eng)

Keyword

CRISPR

directed evolution

multiplexing

in vivo mutagenesis

targeted mutagenesis

yeast

Publication and Content Type

art (subject category)

ref (subject category)