Darwin Assembly: fast, efficient, multi-site bespoke mutagenesis.

Engineering proteins for designer functions and biotechnological applications almost invariably requires (or at least benefits from) multiple mutations to non-contiguous residues. Several methods for multiple site-directed mutagenesis exist, but there remains a need for fast and simple methods to efficiently introduce such mutations - particularly for generating large, high quality libraries for directed evolution. Here, we present Darwin Assembly, which can deliver high quality libraries of over 108 transformants, targeting multiple (> 10) distal sites with minimal wild-type contamination (lower than 0.25% of total population) and which takes a single working day from purified plasmid to library transformation. Darwin Assembly uses commercially available enzymes, can be readily automated, and offers a cost-effective route to highly complex and customizable library generation.