Figure 1.

MbpAgo exhibits DNA-guided RNA endonuclease activity at 37°C. (A) Maximum likelihood phylogenetic tree of characterized Ago proteins. (B) Guide and target oligonucleotides. gDNAs and RNA targets (T-RNA) were used in most experiments. The black triangle indicates the cleavage site. (C)MbpAgo exhibits DNA-guided RNA endonuclease activity. (D)MbpAgo exhibits no DNA cleavage activity. Positions of the cleavage products (P) are indicated on the left of the gels. MbpAgo, guide and target were mixed at a 4:2:1 molar ratio (800 nM MbpAgo preloaded with 400 nM guide, plus 200 nM target) and incubated for 30 min at 37°C. Catalytic dead mutant MbpAgo_DM (DM) was used as a control. Lanes M1 and M2 contain chemically synthesized 34-nt RNA and DNA corresponding to the cleavage products of T-RNA and the DNA target (T-DNA), respectively.