AUTHOR=Wang Yong , Liu Xin-Yuan , Huang Zi-Qin , Li Yan-Yan , Yang Yan-Zhuo , Sayyed Aqib , Sun Feng , Gu Zhi-Qun , Wang Xiaomin , Tan Bao-Cai 

TITLE=PPR-DYW Protein EMP17 Is Required for Mitochondrial RNA Editing, Complex III Biogenesis, and Seed Development in Maize

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.693272

DOI=10.3389/fpls.2021.693272

ISSN=1664-462X

ABSTRACT=<p>The conversion of cytidines to uridines (C-to-U) at specific sites in mitochondrial and plastid transcripts is a post-transcriptional processing event that is important to the expression of organellar genes. Pentatricopeptide repeat (PPR) proteins are involved in this process. In this study, we report the function of a previously uncharacterized PPR-DYW protein, Empty pericarp17 (EMP17), in the C-to-U editing and kernel development in maize. EMP17 is targeted to mitochondria. The loss-function of EMP17 arrests maize kernel development, abolishes the editing at <italic>ccmF</italic><sub><italic>C</italic></sub>-799 and <italic>nad2</italic>-677 sites, and reduces the editing at <italic>ccmF</italic><sub><italic>C</italic></sub>-906 and -966 sites. The absence of editing causes amino acid residue changes in CcmF<sub>C</sub>-267 (Ser to Pro) and Nad2-226 (Phe to Ser), respectively. As CcmF<sub>C</sub> functions in cytochrome <italic>c</italic> (Cyt<italic>c</italic>) maturation, the amount of Cyt<italic>c</italic> and Cyt<italic>c</italic><sub>1</sub> protein is drastically reduced in <italic>emp17</italic>, suggesting that the CcmF<sub>C</sub>-267 (Ser to Pro) change impairs the CcmF<sub>C</sub> function. As a result, the assembly of complex III is strikingly decreased in <italic>emp17</italic>. In contrast, the assembly of complex I appears less affected, suggesting that the Nad2-226 (Phe to Ser) change may have less impact on Nad2 function. Together, these results indicate that EMP17 is required for the C-to-U editing at several sites in mitochondrial transcripts, complex III biogenesis, and seed development in maize.</p>