MORF (Multiple sites organellar RNA editing factor)

MORF proteins

Besides PPR proteins, we identified a novel class of RNA editing factors necessary for multiple RNA editing sites, the MORF proteins (Multiple sites Organellar RNA Editing Factor). MORFs are a novel small protein family (10 genes in Arabidopsis) characterized by a conserved 100 amino acids motif (MORF-box)(Fig. 2).

Gene disruption of the mitochondrially targeted MORF1 and MORF3 proteins results in RNA editing defects at more than 40 sites, respectively. Interestingly, the sites affected in the two mutant lines do not overlap, suggesting that each MORF protein has specific targets. Two plastids targeted MORFs, MORF2 and MORF9, are similarly involved in multiple RNA editing events in the plastids, suggesting common functions of the MORF proteins in RNA editing in both organelles.

Yeast-2-hybrid and Co-IP assay results suggest homo- or heteromeric interactions of MORF proteins in specific combinations and in addition selective PLS type PPR-MORF interactions.

The 3D structural analyses confirmed their dimer interaction (Fig. 3).

Currently we are investigating function of MORF proteins in RNA editing complexes in plant organelles.