Pentatricopeptide repeats

Pentatricopeptide motifs in the N-terminal extension domain of yeast mitochondrial RNA polymerase Rpo41p are not essential for its function

“…In typical PPR proteins, the pentatricopeptide motifs form RNA binding surfaces and usually act as intermediates in interactions between organellar transcripts and other proteins [37][38][39][40][41][42]. Typical RNA-binding PPR proteins are, however, composed of multiple adjacent repeats, whereas in Rpo41p the motifs are few and dispersed.…”

“…Most of them are composed solely of the PPR repeats, while some (found mostly in plants) contain additional C-terminal domains conferring enzymatic activities [37,40]. The mitochondrial RNA polymerase is thus not a typical PPR protein, as it contains only 2 -5 PPR motifs that constitute only a minor portion of the entire sequence.…”

“…Typical PPR proteins contain multiple tandem repeats of a 35 amino acid motif forming two parallel alpha helices, resulting in a solenoid superhelical structure of the entire protein [37,39,42]. Most of them are composed solely of the PPR repeats, while some (found mostly in plants) contain additional C-terminal domains conferring enzymatic activities [37,40].…”

“…Proteins containing the PPR motifs are a large family of RNA-binding factors that can be found in all Eukaryotes [36][37][38][39][40][41][42]. They are particularly abundant in plants, where they constitute the most numerous paralogous families, containing hundreds of sequences per genome [38,42].…”

“…The vast majority of known PPR proteins are involved in various post-transcriptional mechanisms of organellar gene expression (reviewed in [36,37,39,40]). They were extensively studied in both model yeast systems -S. cerevisiae [39] and S. pombe [43], where they play significant roles in maintaining and regulating the expression of mitochondrial genes.…”