Figure 1

PPR repeats in Rfo and PPR-A. The eighteen PPR repeats detected by TPRpred in Rfo and the non-restoring adjacent protein PPR-A (designated gene 24 in [16]) are aligned, with each domain on a separate line. Amino acid differences between the two proteins indicated by asterisks (*) and highlighted according to the type of amino acid occurring in each protein. Portions of the proteins, including the N-terminal region containing the mitochondrial targeting sequence, that do not constitute a PPR domain are enclosed in boxes, with the exception of the portion of PPR-A corresponding to domain 4 of Rfo. The domains are presented on separate lines, numbered according to their position in the sequence and represented in the register proposed by Yin et al. [11] on the basis of the solved structure of a PPR protein bound to its RNA ligand. In this register the first amino acid of each domain corresponds to the second amino acid in the register employed in [3],[12],[15],[20] and the last letter of the preceding domains detected by the Pfam resource [22] employed in [16] and [17].