| Authors |
Gasiunas, Giedrius ; Young, Joshua K ; Karvelis, Tautvydas ; Kazlauskas, Darius ; Urbaitis, Tomas ; Jasnauskaite, Monika ; Grusyte, Mantvyda M ; Paulraj, Sushmitha ; Wang, Po-Hao ; Hou, Zhenglin ; Dooley, Shane K ; Cigan, Mark ; Alarcon, Clara ; Chilcoat, N Doane ; Bigelytė, Greta ; Curcuru, Jennifer L ; Mabuchi, Megumu ; Sun, Zhiyi ; Fuchs, Ryan T ; Schildkraut, Ezra ; Weigele, Peter R ; Jack, William E ; Robb, G Brett ; Venclovas, Česlovas ; Šikšnys, Virginijus |
| Abstract [eng] |
Bacterial Cas9 nucleases from type II CRISPR-Cas antiviral defence systems have been repurposed as genome editing tools. Although these proteins are found in many microbes, only a handful of variants are used for these applications. Here, we use bioinformatic and biochemical analyses to explore this largely uncharacterized diversity. We apply cell-free biochemical screens to assess the protospacer adjacent motif (PAM) and guide RNA (gRNA) requirements of 79 Cas9 proteins, thus identifying at least 7 distinct gRNA classes and 50 different PAM sequence requirements. PAM recognition spans the entire spectrum of T-, A-, C-, and G-rich nucleotides, from single nucleotide recognition to sequence strings longer than 4 nucleotides. Characterization of a subset of Cas9 orthologs using purified components reveals additional biochemical diversity, including both narrow and broad ranges of temperature dependence, staggered-end DNA target cleavage, and a requirement for long stretches of homology between gRNA and DNA target. Our results expand the available toolset of RNA-programmable CRISPR-associated nucleases. |
