Fig. 4.

Replacing modules resulting from FMAs by natural variants. The original variant (left) is replaced by another natural variant with advantageous characteristics (middle). While the intrinsic interactions within the transferred module should already be optimal (thick dotted lines), perturbation of interactions (thin dotted lines) with extrinsic components might affect the overall function of the process. In that case, these extrinsic components must also be exchanged or suitably modified by laboratory evolution (right) to accommodate the chimeric multiprotein complex, perhaps also involving adaptive sequence variation (indicated by altered shading) of contact sites in the complex itself. Note that this approach is not likely to succeed for PSII (see main text) but might be feasible for other instances of FMAs