A seed motif for target RNA capture enables efficient immune defence by a type III-B CRISPR-Cas system

CRISPR-Cas systems provide an adaptive defence against foreign nucleic acids guided by small RNAs (crRNAs) in archaea and bacteria. The Type III CRISPR systems are reported to carry RNase, RNA-activated DNase and cyclic oligoadenylate (cOA) synthetase activity, and are significantly different from other CRISPR systems. However, detailed features of target recognition, which are essential for enhancing target specificity remain unknown in Type...