Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China.
Int J Mol Sci. 2022 Mar 12;23(6):3064. doi: 10.3390/ijms23063064.
In flowering plants, C-to-U RNA editing can be critical to normal functions of mitochondrion-encoded proteins. Mitochondrial C-to-U RNA editing is facilitated by many factors from diverse protein families, of which the pentatricopeptide repeat (PPR) proteins play an important role. Owing to their large number and frequent embryo lethality in mutants, functions of many PPRs remain unknown. In this study, we characterized a mitochondrion-localized DYW-type PPR protein, DEK48, functioning in the C-to-U RNA editing at multiple mitochondrial transcripts in maize. Null mutation of severely arrests embryo and endosperm development, causing a () phenotype, named . DEK48 loss of function abolishes the C-to-U editing at -185, -215, and -376, -977 sites and decreases the editing at 11 other sites, resulting in the alteration of the corresponding amino acids. Consequently, the absence of editing caused reduced assembly and activity of complex I in . Interestingly, we identified a point mutation in causing a deletion of the Tryptophan (W) residue in the DYW motif that abolishes the editing function. In sum, this study reveals the function of DEK48 in the C-to-U editing in mitochondrial transcripts and seed development in maize, and it demonstrates a critical role of the W residue in the DYW triplet motif of DEK48 for the C-to-U editing function in vivo.
在开花植物中，C 到 U 的 RNA 编辑对于线粒体编码蛋白的正常功能至关重要。线粒体 C 到 U 的 RNA 编辑由来自不同蛋白家族的许多因素来辅助完成，其中五肽重复（PPR）蛋白发挥着重要作用。由于其数量众多，且在突变体中常导致胚胎致死，许多 PPR 的功能仍不清楚。在这项研究中，我们鉴定了一个定位于线粒体的 DYW 型 PPR 蛋白 DEK48，该蛋白在玉米中多个线粒体转录本的 C 到 U 的 RNA 编辑中发挥作用。de 突变严重阻滞了胚胎和胚乳的发育，导致了一种 ()表型，命名为。DEK48 功能丧失导致 -185、-215 和 -376、-977 位点的 C 到 U 编辑缺失，并减少了 11 个其他位点的编辑，导致相应氨基酸的改变。因此，编辑的缺失导致 中复合体 I 的组装和活性降低。有趣的是，我们在 中鉴定出一个点突变，导致 DYW 基序中的色氨酸（W）残基缺失，从而使编辑功能丧失。总之，本研究揭示了 DEK48 在玉米线粒体转录本的 C 到 U 编辑和种子发育中的功能，并表明 DEK48 中 DYW 三肽基序中的 W 残基对于体内的 C 到 U 编辑功能具有重要作用。
