Functional characterization of archaeal homologs of human nuclear RNase P proteins Rpp21 and Rpp29 provides insights into the molecular basis of their cooperativity in catalysis

A mechanistic model for the synergistic activation of PhopRNA by PhoRpp21 and PhoRpp29. PhoRpp21 binds to the loop between P11 and P12 helices in PhopRNA and serves as a scaffold for PhoRpp29 to optimize a structural conformation of a positively charged edge composed of lysine residues (●) at α2 in PhoRpp21and C-terminal residues (▋) in PhoRpp29 on the protein complex which probably stabilize stacking interactions between PhopRNA and pre-tRNA. ▲ indicates the processing site in pre-tRNA.181