An evolutionarily conserved P‐subfamily pentatricopeptide repeat protein is required to splice the plastid ndhA transcript in the moss Physcomitrella patens and Arabidopsis thaliana. (1st April 2018)

• Record Type: Journal Article
• Authors: Ito, Ayaka; Sugita, Chieko; Ichinose, Mizuho; Kato, Yoshinobu; Yamamoto, Hiroshi; Shikanai, Toshiharu; Sugita, Mamoru
• Is Part Of: Plant journal. Volume 94:Number 4(2018)
• Page Start: 638
• Page End: 648
• Publication Date: 2018-04-01
• Subjects: P‐subfamily PPR protein -- splicing -- ndhA -- plastid -- Physcomitrella patens -- Arabidopsis thaliana; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.13884
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: Pentatricopeptide repeat (PPR) proteins are known to play important roles in post‐transcriptional regulation in plant organelles. However, the function of the majority of PPR proteins remains unknown. To examine their functions, Physcomitrella patens PpPPR_66 knockout (KO) mutants were generated and characterized. The KO mosses exhibited a wild‐type‐like growth phenotype but showed aberrant chlorophyll fluorescence due to defects in chloroplast NADH dehydrogenase‐like (NDH) activity. Immunoblot analysis suggested that disruption of PpPPR_66 led to a complete loss of the chloroplast NDH complex. To examine whether the loss of PpPPR_66 affects the expression of plastid ndh genes, the transcript levels of 11 plastid ndh genes were analyzed by reverse transcription PCR. This analysis indicated that splicing of the ndhA transcript was specifically impaired while mRNA accumulation levels as well as the processing patterns of other plastid ndh genes were not affected in the KO mutants. Complemented PpPPR_66 KO lines transformed with the PpPPR_66 full‐length cDNA rescued splicing of the ndhA transcript. Arabidopsis thaliana T‐DNA tagged lines of a PPR_66 homolog ( At2 g35130 ) showed deficient splicing of the ndhA transcript. This indicates that the two proteins are functionally conserved between bryophytes and vascular plants. An in vitro RNA‐binding assay demonstrated that the recombinant PpPPR_66 bound preferentially to the region encompassing a part of exon 1 to a 5′ part of the ndhA group II intron. Taken together, these results indicate that PpPPR_66 acts as a specific factor to splice ndhA pre‐mRNA. Significance Statement: Pentatricopeptide repeat (PPR) proteins play important roles in various RNA processing steps in plastids and mitochondria. Here we identified an evolutionarily conserved P‐subfamily PPR protein which is required for splicing of ndhA pre‐mRNA in plastids of the non‐vascular plant Physcomitrella patens and the vascular plant Arabidopsis thaliana .