Two interacting PPR proteins are major Arabidopsis editing factors in plastid and mitochondria

Abstract

RNA editing is converting hundreds of cytosines into uridines during organelle gene expression of land plants. The pentatricopeptide repeat (PPR) proteins are at the core of this posttranscriptional RNA modification. Even if a PPR protein defines the editing site, a DYW domain of the same or another PPR protein is believed to catalyze the deamination. To give insight into the organelle RNA editosome, we performed tandem affinity purification of the plastidial CHLOROPLAST BIOGENESIS 19 (CLB19) PPR editing factor. Two PPR proteins, dually targeted to mitochondria and chloroplasts, were identified as potential partners of CLB19. These two proteins, a P-type PPR and a member of a small PPR-DYW subfamily, were shown to interact in yeast. Insertional mutations resulted in embryo lethality that could be rescued by embryo-specific complementation. A transcriptome analysis of these complemented plants showed major editing defects in both organelles with a very high PPR type specificity, indicating that the two proteins are core members of E+-type PPR editosomes.

The pentatricopeptide repeat protein EMPTY PERICARP8 is required for the splicing of three mitochondrial introns and seed development in maize

“…GRP23 was also identified in a complex including PMH2 and nMAT2 in mitochondria (Zmudjak et al ., ). Recently, PPR proteins DYW2 and NUWA were found to interact with the mitochondrial PPR protein SLO2 and chloroplast PPR protein CLB19 for RNA editing (Andres‐Colas et al ., ; Guillaumot et al ., ). Hence, evidence supports the idea that mitochondrial intron splicing may involve a putative mitospliceosome.…”

Towards a plant model for enigmatic U‐to‐C RNA editing: the organelle genomes, transcriptomes, editomes and candidate RNA editing factors in the hornwort Anthoceros agrestis

“…). In the angiosperm models, such truncations are compensated for by separate DYW domains provided in trans (Boussardon et al , ; Andrés‐Colás et al , ; Diaz et al , ; Guillaumot et al , ). Interestingly, we also identified three small DYW‐only proteins outside of the large PLS‐type PPR gene family in the A. agrestis genome, which feature the conserved cytidine deaminase signatures and a terminal DYW tripeptide (Fig.…”

“…However, the setup of organelle RNA editing is evidently more complex in flowering plants, where truncated proteins require interactions with DYW domains supplied in trans, frequently mediated by extra helper proteins (e.g. NUWA and multiple organellar RNA editing factor (MORF)/RNA-editing factor interacting protein (RIP) proteins) in much more complex editosomes (Takenaka et al, 2012;Bentolila et al, 2012;Boussardon et al, 2012;Sun et al, 2013Sun et al, , 2015Sun et al, , 2016Zehrmann et al, 2015;Diaz et al, 2017;Bayer-Cs asz ar et al, 2017;Andr es-Col as et al, 2017;Guillaumot et al, 2017;Sandoval et al, 2019).…”

Control of Retrograde Signaling by Rapid Turnover of GENOMES UNCOUPLED1

“…PPRs usually confer RNA-binding activity (Small and Peeters, 2000), accumulating evidence 566 suggests the ability of at least some PPR-like domains to mediate protein-protein interactions 567 (Bentolila et al, 2012;Spahr et al, 2016;Andres-Colas et al, 2017;Guillaumot et al, 2017), 568 similar to the related tetratricopeptide repeat (TPR) motifs (Goebl and Yanagida, 1991;Das et al, 569 1998;Allan and Ratajczak, 2011). Since GUN1 is most likely not a nucleic acid-binding protein 570 , its PPR tracts may represent another example of PPR motifs engaging in 571 protein-protein interactions (Bentolila et al, 2012;Spahr et al, 2016;Andres-Colas et al, 2017).…”