A rice dual-localized pentatricopeptide repeat protein is involved in organellar RNA editing together with OsMORFs.

Haijun Xiao,Chenzi Ni,Qiannan Zhang,Jun Hu,Leilei Peng,Yingguo Zhu,Wei Liu,Jishuai Huang,Feiya Zhong,Yanghong Xu

doi:10.1093/jxb/ery108

Abstract

In flowering plants, various RNA editing events occur in the mitochondria and chloroplasts as part of post-transcriptional processes. Although several pentatricopeptide repeat (PPR) proteins and multiple organellar RNA editing factors (MORFs) have been identified as RNA editing factors, the underlying mechanism of PPRs and the cooperation among these proteins are still obscure. Here, we identified a rice dual-localized PPR protein, OsPGL1. The loss of function of OsPGL1 resulted in defects in both chloroplast RNA editing of ndhD-878 and mitochondrial RNA editing of ccmFc-543, both of which could be restored in transgenic complementation lines. Despite synonymous editing of ccmFc-543, the loss of editing of ndhD-878 caused a failed conversion of serine to leucine, leading to chloroplast dysfunction and defects in the photosynthetic complex; the results of additional experiments demonstrated that OsPGL1 directly binds to both transcripts. Interactions between three OsMORFs (OsMORF2/8/9) and OsPGL1 both in vitro and in vivo were confirmed, implying that OsPGL1 functions in RNA editing via an editosome. These findings also suggested that OsMORFs assist with and contribute to a flexible PPR-RNA recognition model during RNA editing. These results indicate that, in cooperation with PPRs, OsPGL1 is required for RNA editing. In addition, our study provides new insights into the relationship between RNA editing and plant development.

Highlights

RNA editing is broadly defined as a post-transcriptional process whereby the sequence of an RNA molecule is altered from that of its master DNA (Covello and Gray, 1989)
RNA editing rarely occurs in animals; only a few cases have been reported, including C-to-U RNA editing catalyzed by the apolipoprotein B mRNA editing enzyme (APOBEC) (Teng et al, 1993), U-to-C RNA editing by a putative editing reaction reported in mouse mitochondria (Villegas et al, 2002), and adenosine (A)-to-inosine (I) editing by adenosine deaminase acting on RNA (ADAR)
OsPGL1 is a dual-localized pentatricopeptide repeat (PPR) protein involved in RNA editing

Summary

Introduction

RNA editing is broadly defined as a post-transcriptional process whereby the sequence of an RNA molecule is altered from that of its master DNA (Covello and Gray, 1989). RNA editing is widespread among eukaryotic cells and is abundant in plant mitochondria and chloroplasts. RNA editing rarely occurs in animals; only a few cases have been reported, including C-to-U RNA editing catalyzed by the apolipoprotein B mRNA editing enzyme (APOBEC) (Teng et al, 1993), U-to-C RNA editing by a putative editing reaction reported in mouse mitochondria (Villegas et al, 2002), and adenosine (A)-to-inosine (I) editing by adenosine deaminase acting on RNA (ADAR). The majority of editing in plants involves mitochondrial and plastid transcripts; A-to-I editing of cytosolic tRNAs occurs (Chateigner-Boutin and Small, 2010). More than 40 plastid and more than 600 mitochondrial C-to-U RNA editing sites have been reported in Arabidopsis (Bentolila et al, 2013b; Ruwe et al, 2013), while 21 plastid and 491 mitochondrial C-to-U editing sites have been reported in rice (Corneille et al, 2000; Notsu et al, 2002)

Methods

Results

Conclusion