FIGURE 5.

Insertional editing cycle. (A) Model depicting the events involved in the cotranscriptional insertion of nonencoded nucleotides into Physarum mitochondrial transcripts. Black and gray lines represent mitochondrial DNA and RNA, respectively. Shaded objects represent the mitochondrial RNA polymerase, with different shapes indicating potential conformational states (hypothetical) that might be needed to accommodate extra nucleotides in the active site. Individual steps are described in the text. (B) Schematic illustration of the location of the template elements required for C insertion defined in this work and the likely roles played by upstream and downstream regions.