Fig. 2

The knowledge driven DBTL cycle for rational dopamine strain engineering. In the upper part, the schematic pathway for dopamine production based on l-tyrosine via l-DOPA to dopamine is shown. The enzymes 4-hydroxyphenylacetate 3-monooxygenase (HpaBC) and l-DOPA decarboxylase (Ddc) are responsible for the respective conversions. The rational design of the pathway is performed by preliminary in vitro experiments. Based on the optimal ratio of the pathway components, the DBTL cycle can be entered in a rational way. Therefore, effective and straightforward strain engineering is possible. Partly created in BioRender. Takors (2025) https://biorender.com/m17m852