The DNA sequence of most genomes predicts the sequence of the mRNA and finally of the protein encoded. Sometimes, however, the nucleotide identities in the derived mRNA sequence are altered by a process called RNA editing.

In the mitochondria of flowering plants RNA editing changes about 400 C's in mRNAs and tRNAs to U's. We investigate with in vitro systems how such a nucleotide is identified for editing and which enzymes and cofactors are involved. These investigations show that the sequence of about 20 upstream nucleotides is the signal for of a nucleotide to be edited. In parallel approaches we use genetic methods to determine the factors which recognize this signal and which edit the C nucleotide.