We modify a fatty acid synthase so that it behaves more like a polyketide synthase. Specifically, we modify the keto reductase domain, which is responsible for the reduction of the beta-carbonyl unit, by (i) introducing a structural element found in PKSs, or (ii) by deleting one hydrogen bond involved in aligning the substrate. The engineered FAS initially performs normal fatty acid synthesis, and switches to a non-reducing mode, which leads to the formation of of ring-shaped pyrone compounds.
See link: https://doi.org/10.1002/cbic.202500888