US Patent 9422553 Prokaryotic RNAi-like system and methods of use

Provided herein are methods for inactivating a target polynucleotide. The methods use a psiRNA having a 5′ region and a 3′ region. The 5′ region includes, but is not limited to, 5 to 10 nucleotides chosen from a repeat from a CRISPR locus immediately upstream of a spacer. The 3′ region is substantially complementary to a portion of the target polynucleotide. The methods may be practiced in a prokaryotic microbe or in vitro. Also provided are polypeptides that have endonuclease activity in the presence of a psiRNA and a target polynucleotide, and methods for using the polypeptides.