A truncated MEF11 protein shows site-specific effects on mitochondrial RNA editing.

RNA editing in flowering plant mitochondria post-transcriptionally alters several hundred nucleotides from C to U, mostly in mRNAs. We recently identified the nuclear encoded gene MEF11 which is involved in RNA editing of three sites in mRNAs coding for subunits of respiratory chain complexes in Arabidopsis thaliana. In the mef11-2 mutant a T-DNA insert alters the C-terminal part of the DYW domain. This insertion blocks RNA editing at sites cox 3-422 and site nad4-124 completely, but only partially at ccb203-344. Transcription analysis shows that RNA editing is not defective due to disturbance of transcripts from the mef11-2 locus. These observations suggest that the enzymatic activity or its recruitment is not compromised by the alteration of the C-terminus of MEF11.