Mitochondrial Pentatricopeptide Repeat Protein, EMB2794, Plays a Pivotal Role in NADH Dehydrogenase Subunit nad2 mRNA Maturation in Arabidopsis thaliana.

Fernanda Marchetti, Maximiliano Cainzos, Sofía Shevtsov, Juan Pablo Córdoba, Laure Dora Sultan, Axel Brennicke, Mizuki Takenaka, Gabriela Pagnussat, Oren Ostersetzer-Biran, Eduardo Zabaleta

Plant & cell physiology 2020 Jun 01

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The Arabidopsis genome encodes >450 proteins containing the pentatricopeptide repeat (PPR) motif. The PPR proteins are classified into two groups, termed as P and P Long-Short (PLS) classes. Typically, the PLS subclass proteins are mainly involved in the RNA editing of mitochondrial and chloroplast transcripts, whereas most of the analyzed P subclass proteins have been mainly implicated in RNA metabolism, such as 5' or 3' transcript stabilization and processing, splicing and translation. Mutations of PPR genes often result in embryogenesis and altered seedling developmental defect phenotypes, but only a limited number of ppr mutants have been characterized in detail. In this report, we show that null mutations in the EMB2794 gene result in embryo arrest, due to altered splicing of nad2 transcripts in the Arabidopsis mitochondria. In angiosperms, nad2 has five exons that are transcribed individually from two mitochondrial DNA regions. Biochemical and in vivo analyses further indicate that recombinant or transgenic EMB2794 proteins bind to the nad2 pre-mRNAs in vitro as well as in vivo, suggesting a role for this protein in trans-splicing of nad2 intron 2 and possibly in the stability of the second pre-mRNA of nad2. Homozygous emb2794 lines, showing embryo-defective phenotypes, can be partially rescued by the addition of sucrose to the growth medium. Mitochondria of rescued homozygous mutant plants contain only traces of respiratory complex I, which lack the NADH-dehydrogenase activity. © The Author(s) 2020. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Citation

Fernanda Marchetti, Maximiliano Cainzos, Sofía Shevtsov, Juan Pablo Córdoba, Laure Dora Sultan, Axel Brennicke, Mizuki Takenaka, Gabriela Pagnussat, Oren Ostersetzer-Biran, Eduardo Zabaleta. Mitochondrial Pentatricopeptide Repeat Protein, EMB2794, Plays a Pivotal Role in NADH Dehydrogenase Subunit nad2 mRNA Maturation in Arabidopsis thaliana. Plant & cell physiology. 2020 Jun 01;61(6):1080-1094