title: Empty pericarp7 encodes a mitochondrial E-subgroup pentatricopeptide repeat protein that is required for ccmFN editing, mitochondrial function and seed development in maize.
abstract: RNA editing, converting cytidines (C) to uridines (U) at specific sites in the transcripts of mitochondria and plastids, plays a critical role in organelle gene expression in land plants. Recently pentatricopeptide repeat (PPR) proteins were identified as site-specific recognition factors for RNA editing. In this study, we characterized an empty pericarp7 mutant (emp7) in Zea mays (maize), which confers an embryo-lethal phenotype. In emp7 mutants, mitochondrial functions are seriously perturbed, resulting in a strikingly reduced respiration rate. Emp7 encodes an E-subgroup PPR protein that is localized exclusively in the mitochondrion. Null mutation of Emp7 abolishes the C → U editing of ccmF(N) transcript solely at position 1553. CcmF(N) is coding for a subunit of heme lyase complex in the cytochrome c maturation pathway. The resulting Phe → Ser substitution in CcmF(N) leads to the loss of CcmF(N) protein and a strikingly reduced c-type cytochrome. Consequently, the mitochondrial cytochrome-linked respiratory chain is impaired as a result of the disassembly of complex III in the emp7 mutant. These results indicate that the PPR-E subgroup protein EMP7 is required for C → U editing of ccmF(N) -1553 at a position essential for cytochrome c maturation and mitochondrial oxidative phosphorylation, and hence is essential to embryo and endosperm development in maize.
authors: Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, 250100, China.
authors: Feng
authors: F
authors: Sun
authors: Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Xiaomin
authors: X
authors: Wang
authors: Institut de biologie moléculaire des plantes CNRS, Associé à l'Université de Strasbourg, 12 rue du Général Zimmer, 67084, Strasbourg, France.
authors: Géraldine
authors: G
authors: Bonnard
authors: School of Life Sciences, The Chinese University of Hong Kong, N.T, Hong Kong.
authors: Yun
authors: Y
authors: Shen
authors: School of Life Sciences, The Chinese University of Hong Kong, N.T, Hong Kong.
authors: Zhihui
authors: Z
authors: Xiu
authors: School of Life Sciences, The Chinese University of Hong Kong, N.T, Hong Kong.
authors: Xiaojie
authors: X
authors: Li
authors: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
authors: Dahai
authors: D
authors: Gao
authors: School of Life Sciences, The Chinese University of Hong Kong, N.T, Hong Kong.
authors: Zhonghang
authors: Z
authors: Zhang
authors: Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, 250100, China.
authors: Bao-Cai
authors: BC
authors: Tan
mesh_terms: D045304:Cytochromes c / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D003313:Zea mays / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D024101:Mitochondrial Proteins; D010940:Plant Proteins; D045304:Cytochromes c
keywords: cytochrome c maturation; empty pericarp7; maize; mitochondrion; seed development