Editing of Chloroplast rps14 by PPR Editing Factor EMB2261 Is Essential for Arabidopsis Development.

Yueming K. Sun,Bernard Gutmann,Ian Small,Aaron Yap,Peter Kindgren

doi:10.3389/fpls.2018.00841

Yueming K. Sun, Bernard Gutmann + Show 3 more

Open Access

https://doi.org/10.3389/fpls.2018.00841

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Abstract

RNA editing in plastids is known to be required for embryogenesis, but no single editing event had been shown to be essential. We show that the emb2261-2 mutation is lethal through a failure to express an editing factor that specifically recognizes the rps14-2 site. EMB2261 was predicted to bind the cis-element upstream of the rps14-2 site and genetic complementation with promoters of different strength followed by RNA-seq analysis was conducted to test the correlation between rps14-2 editing and EMB2261 expression. Rps14-2 is the only editing event in Arabidopsis chloroplasts that correlates with EMB2261 expression. Sequence divergence between the cis-element and the EMB2261 protein sequence in plants where rps14-2 editing is not required adds support to the association between them. We conclude that EMB2261 is the specificity factor for rps14-2 editing. This editing event converts P51 in Rps14 to L51, which is conserved among species lacking RNA editing, implying the importance of the editing event to Rps14 function. Rps14 is an essential ribosomal subunit for plastid translation, which, in turn, is essential for Arabidopsis embryogenesis.

Highlights

RNA editing is a crucial process in plant organellar gene expression
PPR Editing Factor EMB2261 Is Predicted to Edit rps14-2 in Arabidopsis Chloroplasts
With a different genetic approach based on a different mutant allele of the EMB2261 gene, we confirm the conclusion of Jiang et al (2018), claiming that EMB2261/ECD1 is the editing specificity factor of rps14-2 in Arabidopsis chloroplasts and is essential for Arabidopsis development

Summary

Introduction

RNA editing is a crucial process in plant organellar gene expression. In flowering plants, it involves cytidine (C) to uridine (U) deamination (Takenaka et al, 2013b). RNA editing in plant organelles is facilitated by organelletargeted pentatricopeptide repeat (PPR) editing factors (Barkan and Small, 2014). They contain multiple tandem helix-loop-helix PPR motifs that bind to the RNA sequence just 5 to the edited nucleotide in a one-motif to one-base manner, acting as site recognition factors (Barkan and Small, 2014). Amino acids at two positions in each PPR motif recognize one of the four RNA bases, denoted as the PPR-RNA recognition code (Barkan et al, 2012; Takenaka et al, 2013a; Yagi et al, 2013a). Nineteen PPR editing factors have been identified accounting for 30 out of the 34 major editing sites in Arabidopsis chloroplasts

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