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Pentacotripeptide-repeat region of PRORP Pentatricopeptide repeat (PPR) proteins are a large family of modular RNA-binding proteins which mediate several aspects of gene expression primarily in organelles but also in the nucleus. PPR_long is the region of Arabidopsis protein-only RNase P (PRORP) enzyme that consists of up to eleven alpha-helices. PRORPs are a class of RNA processing enzymes that catalyze maturation of the 5' end of precursor tRNAs in Eukaryotes. All PPR proteins contain tandemly repeated sequence motifs (the PPR motifs) which can vary in number. The series of helix-turn-helix motifs formed by PPR motifs throughout the protein produces a superheros with a central groove that allows the protein to bind RNA. Proteins containing PPR motifs are known to have roles in transcription, RNA processing, splicing, stability, editing, and translation. Over a decade after the discovery of PPR proteins, the super-helical structure was confirmed. The protein-only mitochondrial RNase P crystal structure from Arabidopsis thaliana (PRORP1) confirmed the role of its PPR motifs in pre-tRNA binding and suggest it has evolved independently from other RNase P proteins that rely on catalytic RNA. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",