Ma Shuai, Yang Wenzhu, Liu Xiaoqing, Li Suzhen, Li Ye, Zhu Jiameng, Zhang Chunyi, Lu Xiaoduo, Zhou Xiaojin, Chen Rumei
Crop Functional Genome Research Center, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Key Laboratory of Chemical and Biological Processing Technology for Farm Products of Zhejiang Province , Zhejiang University of Science and Technology, Hangzhou 310023, China.
Plant Physiol. 2022 Jun 1;189(2):611-627. doi: 10.1093/plphys/kiac086.
Mitochondrial function relies on the assembly of electron transport chain complexes, which requires coordination between proteins encoded by the mitochondrion and those of the nucleus. Here, we cloned a maize (Zea mays) cytochrome c maturation FN stabilizer1 (CNS1) and found it encodes a pentatricopeptide repeat (PPR) protein. Members of the PPR family are widely distributed in plants and are associated with RNA metabolism in organelles. P-type PPR proteins play essential roles in stabilizing the 3'-end of RNA in mitochondria; whether a similar process exists for stabilizing the 5'-terminus of mitochondrial RNA remains unclear. The kernels of cns1 exhibited arrested embryo and endosperm development, whereas neither conventional splicing deficiency nor RNA editing difference in mitochondrial genes was observed. Instead, most of the ccmFN transcripts isolated from cns1 mutant plants were 5'-truncated and therefore lacked the start codon. Biochemical and molecular data demonstrated that CNS1 is a P-type PPR protein encoded by nuclear DNA and that it localizes to the mitochondrion. Also, one binding site of CNS1 located upstream of the start codon in the ccmFN transcript. Moreover, abnormal mitochondrial morphology and dramatic upregulation of alternative oxidase genes were observed in the mutant. Together, these results indicate that CNS1 is essential for reaching a suitable level of intact ccmFN transcripts through binding to the 5'-UTR of the RNAs and maintaining 5'-integrity, which is crucial for sustaining mitochondrial complex III function to ensure mitochondrial biogenesis and seed development in maize.
线粒体功能依赖于电子传递链复合物的组装，这需要线粒体编码的蛋白质与细胞核编码的蛋白质之间的协调。在此，我们克隆了一个玉米（Zea mays）细胞色素c成熟FN稳定因子1（CNS1），发现它编码一个五肽重复（PPR）蛋白。PPR家族成员广泛分布于植物中，并与细胞器中的RNA代谢相关。P型PPR蛋白在稳定线粒体RNA的3'末端方面发挥着重要作用；线粒体RNA 5'末端的稳定是否存在类似过程尚不清楚。cns1的籽粒表现出胚胎和胚乳发育停滞，而未观察到线粒体基因的常规剪接缺陷或RNA编辑差异。相反，从cns1突变体植株中分离出的大多数ccmFN转录本在5'端被截短，因此缺少起始密码子。生化和分子数据表明，CNS1是一种由核DNA编码的P型PPR蛋白，定位于线粒体。此外，CNS1的一个结合位点位于ccmFN转录本起始密码子的上游。此外，在突变体中观察到线粒体形态异常和交替氧化酶基因的显著上调。这些结果共同表明，CNS1通过与RNA的5'-UTR结合并维持5'-完整性，对于达到合适水平的完整ccmFN转录本至关重要，这对于维持线粒体复合物III功能以确保玉米的线粒体生物发生和种子发育至关重要。
