RIBONUCLEASE-P PROTEIN-STRUCTURE - EVOLUTIONARY ORIGINS IN THE TRANSLATIONAL APPARATUS

The crystal structure of Bacillus subtilis ribonuclease P protein is r eported at 2.6 angstroms resolution. This protein binds to ribonucleas e P RNA to form a ribonucleoprotein holoenzyme with optimal catalytic activity. Mutagenesis and biochemical data indicate that an unusual le ft-handed beta alpha beta crossover connection and a large central cle ft in the protein form conserved RNA binding sites; a metal binding lo op may comprise a third RNA binding site. The unusual topology is part ly shared with ribosomal protein S5 and the ribosomal translocase elon gation factor G, which suggests evolution from a common RNA binding an cestor in the primordial translational apparatus.