Takamasa Teramoto, Kipchumba J Kaitany, Yoshimitsu Kakuta, Makoto Kimura, Carol A Fierke, and Traci M Tanaka Hall
Nucleic Acids Research, gkaa627, https://doi.org/10.1093/nar/gkaa627
This article describes the structural basis and mechanism by which ‘protein only’ RNase P (‘PRORP’; an endoribonuclease enzyme that removes 5’ leader sequences from pre-tRNAs) recognizes and acts upon its substrate. Although substrate recognition and nuclease activity of the RNP RNase P variants is well studied, many questions remain about the protein-only forms that were discovered 25 years after the ribozymes. This study illustrates the details of substrate recognition by the pentatricopeptide repeats (PPR) of PRORP enzymes, with a crystal structure of the PPR domain of PRORP1 in complex with tRNA that demonstrates two evolutionary principles: (1) that α-helical PPR motifs recognize conserved sequence and structural features of tRNAs in addition to their well-established role in single-stranded RNA recognition, and (2) that the peptide motifs have converged on a similar solution to tRNA ‘elbow’ recognition as functional RNAs.