CRISPR-Cas9 based genome engineering tools have revolutionized fundamental research and
biotechnological exploitation of both eukaryotes and prokaryotes. However, the mesophilic nature
of the already established Cas9 systems restricts their applicability, excluding thermophiles and
cellular environments in which mesophilic enzymes are easily inactivated. Here, we identify and
characterize Cas9 from the CRISPR-Cas type-IIC system of the thermophilic bacterium Geobacillus
thermodenitrificans T12 as an RNA-guided DNA endonuclease. We provide fundamental insights
into a thermophilic CRISPR-Cas family member and describe our work towards the development of
a genome editing and silencing tool readily applicable to thermophiles.
