MEF9, an E-subclass pentatricopeptide repeat protein, is required for an RNA editing event in the nad7 transcript in mitochondria of Arabidopsis.
RNA editing in plants alters specific nucleotides from C to U in mRNAs in plastids and in mitochondria. I here characterize the nuclear gene MITOCHONDRIAL EDITING FACTOR9 (MEF9) that is required for RNA editing of the site nad7-200 in the nad7 mitochondrial mRNA in Arabidopsis (Arabidopsis thaliana). The MEF9 protein belongs to the E subfamily of pentatricopeptide repeat proteins and unlike the three previously identified mitochondrial editing factors MEF1 and MEF11 in Arabidopsis and OGR1 in rice (Oryza sativa) does not contain a DYW C-terminal domain. In addition, the E domain is incomplete, but seems to be functionally required, since one of the two independent EMS mutants encodes a MEF9 protein truncated by a stop codon at the beginning of the E domain. In both mutant plants premature stop codons in MEF9 inactivate RNA editing at site nad7-200. The homozygous mutant plants are viable and develop rather normally. The lack of RNA editing at site nad7-200 thus seems to be tolerated although this editing event is conserved in most plant species or the genomic sequence already codes for a T at this position, resulting in a generally conserved amino acid codon.
Takenaka
Mizuki
M
Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany. mizuki.takenaka@uni-ulm.de
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018389:Codon, Nonsense; D018506:Gene Expression Regulation, Plant; D008928:Mitochondria / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D018087:Plastids / Q000235:genetics; D017393:RNA Editing; D012333:RNA, Messenger / Q000378:metabolism; D018749:RNA, Plant / Q000378:metabolism
D029681:Arabidopsis Proteins; D018389:Codon, Nonsense; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D018749:RNA, Plant