Figure 2.

Design of plastid-based metabolic devices. A, Intercistronic expression elements (IEEs; Zhou et al., 2007) can be used to design synthetic operons composed of n genes of interest (GOIs) under the control of a single promoter. Alternatively, each transgene can be controlled by its own promoter. SD, Shine-Dalgarno sequence; SMG, selectable marker gene. B, Expression of a GOI can be controlled by a synthetic 5′-UTR that is specifically stabilized by a designer PPR protein (that recognizes a different binding sequence than all other RNA-binding proteins present in the plastid).