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  • Efficient oligo nucleotide ...
    Nødvig, Christina S.; Hoof, Jakob B.; Kogle, Martin E.; Jarczynska, Zofia D.; Lehmbeck, Jan; Klitgaard, Dorte K.; Mortensen, Uffe H.

    Fungal genetics and biology, June 2018, 2018-06-00, 20180601, Letnik: 115
    Journal Article

    •A tool, TAPE, for identification of efficient protospacers was implemented.•An efficient polymerase III promoter for production of sgRNA is presented.•tRNAs were used as ribozyme substrates to release sgRNA species.•Single-stranded oligonucleotides were used as repair templates for gene alterations.•Showing that the tools can be combined and used for multiplex experiments. CRISPR-Cas9 technologies are revolutionizing fungal gene editing. Here we show that survival of specific Cas9/sgRNA mediated DNA double strand breaks (DSBs) depends on the non-homologous end-joining, NHEJ, DNA repair pathway and we use this observation to develop a tool, TAPE, to assess protospacer efficiency in Aspergillus nidulans. Moreover, we show that in NHEJ deficient strains, highly efficient marker-free gene targeting can be performed. Indeed, we show that even single-stranded oligo nucleotides efficiently work as repair templates of specific Cas9/sgRNA induced DNA DSBs in A. nidulans, A. niger, and in A. oryzae indicating that this type of repair may be wide-spread in filamentous fungi. Importantly, we demonstrate that by using single-stranded oligo nucleotides for CRISPR-Cas9 mediated gene editing it is possible to introduce specific point mutations as well gene deletions at efficiencies approaching 100%. The efficiency of the system invites for multiplexing and we have designed a vector system with the capacity of delivering Cas9 and multiple sgRNAs based on polymerase III promoters and tRNA spacers. We show that it is possible to introduce two point mutations and one gene insertion in one transformation experiment with a very high efficiency. Our system is compatible with future high-throughput gene-editing experiments.