A six‐repeat PPR protein WPR directly binds target RNAs and coordinates chloroplast RNA processing via dual recruitment of MORF1 , MORF8b , and CAF2 proteins in rice

作者：Bo Zhao, Guojuan Xu, Yajun Zhu, Hui Zhang, Yuanbo Zhang, Chunxue Wei, Xi Chen, Zhichao Wu, Ruifang Liu, Kai Chen, Congcong Shen, Ling Ding, Wang Xu, Wenhui Jiang, W. Frank An, Lei Ren, Xu Zhan, Jianlong Xu, Yong Xiang · 发表于：The Plant Journal · 年份：2025 · DOI：10.1111/tpj.70526 · 被引用次数：3 · 研究领域：Photosynthetic Processes and Mechanisms、RNA and protein synthesis mechanisms、RNA regulation and disease

Pentatricopeptide repeat (PPR) proteins are key regulators of organelle RNA metabolism in plants, yet their precise mechanisms in chloroplast RNA processing remain unclear. Here, we identify WPR, a unique P-type PPR protein in rice (Oryza sativa L.), as a critical factor in chloroplast RNA splicing and editing. A ~112-kb chromosomal inversion upstream of WPR causes an albino panicle rachis phenotype (wpr mutant), while complete loss of WPR function leads to seedling lethality. WPR deficiency disrupts the splicing of multiple group II introns (atpF, ndhA, ndhB, petB, rpl2, and rps12) and impairs RNA editing in transcripts such as ndhA, ndhB, ndhG, rps14, and ycf3. Electrophoretic mobility shift assay (EMSA) data confirm that WPR directly binds to precursor mRNAs of atpF, ndhA, petB, rpl2, and rps12. Strikingly, WPR interacts with both RNA editing factors (MORF1, MORF8b) and the splicing factor CAF2, but not with other PPR proteins targeting the same transcripts. Unlike most PPR proteins, WPR contains only six PPR repeats, which is the fewest among all functionally characterized rice PPR proteins. With few informative repeats, WPR likely possesses a broad, low-specificity RNA-binding activity. Moreover, WPR may act on chloroplast RNA maturation by recruiting MORFs and CAF2 rather than other PPR proteins, highlighting a novel regulatory mode in which P-type PPR protein may act as an RNA-binding scaffold to integrate diverse RNA-processing machineries. This study advances the und...