Impact of scaffold rigidity on the design and evolution of an artificial Diels-Alderase

Significance

Creating artificial enzymes that catalyze arbitrary chemical reactions is challenging. Although computational approaches to this problem hold great promise, starting designs typically exhibit low efficiency and require extensive optimization through directed evolution. In this study, we chronicle the evolution of a modestly active, computationally designed Diels-Alderase into a proficient biocatalyst for an abiological [4+2] cycloaddition reaction. Biochemical and structural characterization of the evolved enzyme reveals the molecular origins of its enhanced efficiency. The close match between the experimental structure, which changed only subtly over the course of evolution, and the original design model is particularly notable. In addition to enhancing our understanding of the principles of enzymatic catalysis, these findings should aid future efforts to produce active enzymes more reliably.