A Golden Gate compatible system for continuous directed evolution in <i>E. coli</i>

Directed evolution is a technique that allows for protein engineering without prior knowledge. Continuous directed evolution employs gene-specific hypermutation tied to functional selection within a single cell, enabling a broad search of sequence space for gene variants with improved or novel functions. However, currently available techniques for continuous directed evolution can be inflexible or laborious to establish. To address this issue, we present a modular toolkit for deaminase-fused viral RNA polymerase continuous directed evolution, based on Golden Gate assembly. We include an alternative RNA polymerase from phage SP6 and show that it can introduce gene-specific mutations. This work builds on the available repertoire of synthetic biology techniques, brings accessibility and versatility to directed evolution, and enables researchers to build custom and complex plasmids for their own evolutionary campaigns.