Cofactor-independent RNA editing by a synthetic S-type PPR protein.

Pentatricopeptide repeat (PPR) proteins are RNA-binding proteins that are attractive tools for RNA processing in synthetic biology applications given their modular structure and ease of design. Several distinct types of motifs have been described from natural PPR proteins, but almost all work so far with synthetic PPR proteins has focused on the most widespread P-type motifs. We have investigated synthetic PPR proteins based on tandem repeats of the more compact S-type PPR motif found in plant organellar RNA editing factors and particularly prevalent in the lycophyte .

A synthetic RNA editing factor edits its target site in chloroplasts and bacteria.

Members of the pentatricopeptide repeat (PPR) protein family act as specificity factors in C-to-U RNA editing. The expansion of the PPR superfamily in plants provides the sequence variation required for design of consensus-based RNA-binding proteins. We used this approach to design a synthetic RNA editing factor to target one of the sites in the Arabidopsis chloroplast transcriptome recognised by the natural editing factor CHLOROPLAST BIOGENESIS 19 (CLB19).

Divergent receptor proteins confer responses to different karrikins in two ephemeral weeds.

Wildfires can encourage the establishment of invasive plants by releasing potent germination stimulants, such as karrikins. Seed germination of Brassica tournefortii, a noxious weed of Mediterranean climates, is strongly stimulated by KAR, the archetypal karrikin produced from burning vegetation. In contrast, the closely-related yet non-fire-associated ephemeral Arabidopsis thaliana is unusual because it responds preferentially to KAR.