Cycles of progressive realignment of gRNA with mRNA in RNA editing.

We characterized numerous partially edited NADH dehydrogenase 7 and ATPase 6 cDNAs. Most of these have a stretch of incompletely edited sequence at the junction of mature and unedited sequences. The characteristics of the junctions suggest editing of sites multiple times and that editing within each junction does not proceed precisely 3' to 5'. Analyses of gRNAs and corresponding junction sequences predict a series of progressively more stable, but incompletely base-paired, interactions in the junction region. The predicted interactions suggest that the gRNA is progressively realigned with the mRNA being edited. We suggest that gRNA interactions with the mRNA result in regions of lower thermodynamic stability that are selected for editing, thus driving toward the most stable structure, the complete gRNA/mRNA duplex.