bims-plasge 2023-06-18 papers

Issue of 2023–06–18
two papers selected by
Vera S. Bogdanova, ИЦиГ СО РАН

Int J Mol Sci. 2023 May 24. pii: 9203. [Epub ahead of print]24(11):

The ATP Synthase γ Subunit ATPC1 Regulates RNA Editing in Chloroplasts.

Jia Ni, Wenjian Song, Nadia Ahmed Ali, Yayi Zhang, Jiani Xing, Kexing Su, Xingxing Sun, Xiaobo Zhao.

RNA editing is the process of modifying RNA molecules by inserting, deleting, or substituting nucleotides. In flowering plants, RNA editing occurs predominantly in RNAs encoded by the organellar genomes of mitochondria and chloroplasts, and the main type of editing involves the substitution of cytidine with uridine at specific sites. Abnormal RNA editing in plants can affect gene expression, organelle function, plant growth, and reproduction. In this study, we report that ATPC1, the gamma subunit of ATP synthase in Arabidopsis chloroplasts, has an unexpected role in the regulation of editing at multiple sites of plastid RNAs. The loss of function of ATPC1 severely arrests chloroplast development, causing a pale-green phenotype and early seedling lethality. Disruption of ATPC1 increases the editing of matK-640, rps12-i-58, atpH-3'UTR-13210, and ycf2-as-91535 sites while decreasing the editing of rpl23-89, rpoA-200, rpoC1-488, and ndhD-2 sites. We further show that ATPC1 participates in RNA editing by interacting with known multiple-site chloroplast RNA editing factors, including MORFs, ORRM1, and OZ1. The transcriptome in the atpc1 mutant is profoundly affected, with a pattern of defective expression of chloroplast development-related genes. These results reveal that the ATP synthase γ subunit ATPC1 is involved in multiple-site RNA editing in Arabidopsis chloroplasts.

Keywords: MORFs; RNA editing; atpC1; chloroplast; protein interaction

DOI: https://doi.org/10.3390/ijms24119203

Plant Physiol. 2023 Jun 13. pii: kiad341. [Epub ahead of print]

ALBINO EMBRYO AND SEEDLING is required for RNA splicing and chloroplast homeostasis in Arabidopsis.

Hongqiang An, Xiaolong Ke, Lu Li, Yantong Liu, Sihui Yuan, Qiuyu Wang, Xin Hou, Jie Zhao.

Pentatricopeptide repeat (PPR) proteins form a large protein family and have diverse functions in plant development. Here, we identified an ALBINO EMBRYO AND SEEDLING (AES) gene that encodes a P-type PPR protein expressed in various tissues, especially the young leaves of Arabidopsis (Arabidopsis thaliana). Its null mutant aes exhibited collapsed chloroplast membrane system, reduced pigment content and photosynthetic activity, decreased transcript levels of PEP (plastid-encoded polymerase) -dependent chloroplast genes, and defective RNA splicing. Further work revealed that AES could directly bind to psbB-psbT, psbH-petB, rps8-rpl36, clpP, ycf3, and ndhA in vivo and in vitro and that the splicing efficiencies of these genes and the expression levels of ycf3, ndhA, and cis-tron psbB-psbT-psbH-petB-petD decreased dramatically, leading to defective PSI, PSII and Cyt b6f in aes. Moreover, AES could be transported into the chloroplast stroma via the TOC-TIC channel with the assistance of Tic110 and cpSRP54 and may recruit HCF244, SOT1, and CAF1 to participate in the target RNA process. These findings suggested that AES is an essential protein for the assembly of photosynthetic complexes, providing insights into the splicing of psbB operon (psbB-psbT-psbH-petB-petD), ycf3, and ndhA, as well as maintaining chloroplast homeostasis.

Keywords: ALBINO EMBRYO AND SEEDLING (AES); Arabidopsis; RNA splicing; chloroplast; pentatricopeptide repeat (PPR) protein

DOI: https://doi.org/10.1093/plphys/kiad341