Download RNA editing of cytochrome c maturation transcripts is highly

RNA editing of cytochrome c maturation transcripts is highly sensitive to the energy status of leaf cells in Arabidopsis thaliana Mr. Sun Yuzhe
PhD student, HKU
Supervisor: Dr. B. L. Lim
Date: 20th Jan 2017
Time: 15:35-16:00 PM
Venue: 6N11, KBSB
RNA editing in plants is a post‐transcriptional process that modifies cytidines (C) to uridines (U) in organellar RNA transcripts. In angiosperms, pentatricopeptide repeat (PPR) and multiple organellar RNA editing factor (MORF) proteins are essential components of the editosome complex. Overexpression of AtPAP2, a phosphatase located on the outer membranes of two important energy‐producing organelles (chloroplasts and mitochondria), leads to higher energy outputs from these organelles resulting in higher ATP and sugar levels and increased seed yield and growth rate in Arabidopsis thaliana. Yeast two‐hybrid and bimolecular fluorescence complementation assays showed that AtPAP2 can interact with seven out of nine MORF proteins in Arabidopsis thaliana except MORF4 or MORF7. We compared the organellar transcripts of the AtPAP2 OE line with that of the wild‐type at three time points using RNA‐sequencing analysis. In total, 34 editing sites were identified in chloroplast transcripts and 510 editing sites were identified in mitochondrial transcripts. The degrees of editing of most sites did not differ significantly between OE and WT, yet three chloroplast sites and 124 mitochondrial sites were differentially edited. Particularly, some sites on the transcripts of several genes for cytochrome c maturation (Ccm) were differentially edited between the OE and WT samples, including three sites on a conserved tryptophan‐rich region (WWD domain) of CcmFN2 protein, one site on the C‐terminus of the CcmFC protein resulting in a stop codon, and some sites on the transmembrane region of all Ccm proteins. Western blotting of 2D blue native PAGE showed that the patterns of CcmFN1 polypeptides were different between the OE and WT lines. We postulate that overexpression of AtPAP2 may influence cytochrome c biogenesis by modulating RNA editing through its interaction with MORF proteins.