Enzymes
can be engineered at the level of their amino acid sequences
to optimize key properties such as expression, stability, substrate
range, and catalytic efficiencyor even to unlock new catalytic
activities not found in nature. Because the search space of possible
proteins is vast, enzyme engineering usually involves discovering
an enzyme starting point that has some level of the desired activity
followed by directed evolution to improve its “fitness”
for a desired application. Recently, machine learning (ML) has emerged
as a powerful tool to complement this empirical process. ML models
can contribute to (1) starting point discovery by functional annotation
of known protein sequences or generating novel protein sequences with
desired functions and (2) navigating protein fitness landscapes for
fitness optimization by learning mappings between protein sequences
and their associated fitness values. In this Outlook, we explain how
ML complements enzyme engineering and discuss its future potential
to unlock improved engineering outcomes.