Journal Article

The pentatricopeptide repeat protein EMP9 is required for mitochondrial ccmB and rps4 transcript editing, mitochondrial complex biogenesis and seed development in maize

Yan-Zhuo Yang, Bao-Cai Tan, Hong-Chun Wang, Wen-Long Huang, Chunhui Xu, Feng Sun, Shuo Ding, Shu Song

2017

Overview

Pentatricopeptide repeat (PPR) proteins comprise a large family of sequence-specific RNA binding proteins in land plants. Because of its large family size and frequent embryo lethality in the mutants, molecular functions and physiological roles of many PPR proteins are unknown. Through characterization of an empty pericarp9 (emp9) mutant in maize (Zea mays), we defined the functions of EMP9 in mitochondrial RNA editing, respiratory complex formation and seed development. Mu insertions in different regions of Emp9 facilitated dissection of the domain functions of the EMP9. Through genetic and functional analyses of multiple alleles, we showed that deletions of two N-terminal PPR motifs and partial E+ domain do not eliminate the editing function of EMP9. Emp9 encodes an E+ subclass PPR protein that is localized in mitochondria. Loss of EMP9 function abolishes the C-to-U editing of ccmB-43 and rps4-335 sites in mitochondria. The loss of editing at ccmB-43 and rps4-335 affects the maturation of cytochrome c and impairs the biogenesis of mitochondrial respiratory complexes, particularly complex III. This work extends our understanding of PPR-E+ protein in editing function and seed development, and provides insights into the molecular function of mitochondrial CcmB protein in higher plants.

• Publisher: New Phytologist Trust,Wiley Subscription Services, Inc
• Subject: Alleles / Animal embryos / Arabidopsis - genetics / Base Sequence / Biogenesis / Biosynthesis / Complex formation / Corn / Cytochrome c / Cytochromes / Dissection / Editing / embryophytes / empty pericarp9 (emp9) / Endosperm - embryology / Endosperm - genetics / Family size / Gene Expression Regulation, Developmental / Gene Expression Regulation, Plant / Genetic Complementation Test / Lethality / Loss of Function Mutation / maize (Zea mays) / Mitochondria / Mitochondria - metabolism / mitochondrial RNA / mitochondrion / mortality / mutants / Nucleic acids / Nucleotide sequence / Organelle Biogenesis / pentatricopeptide repeat (PPR) protein / Plant Proteins - chemistry / Plant Proteins - metabolism / Plants (botany) / Plants, Genetically Modified / Proteins / Ribonucleic acid / RNA / RNA editing / RNA Editing - genetics / RNA-binding proteins / seed development / Seeds / Seeds - embryology / Seeds - genetics / Sequencing / Transcription / Zea mays / Zea mays - embryology / Zea mays - genetics