Discovery and interaction of four key biosynthetic enzymes under co-regulation for dopamine biosynthesis with marine Meyerozyma guilliermondii GXDK6 and Bacillus aryabhattai NM1-A2

Dopamine has proven effective in treating conditions such as depression and myocardial infarction. The marine Meyerozyma guilliermondii GXDK6 and Bacillus aryabhattai NM1-A2, both known for their robust nitrogen conversion capabilities, were selected for co-fermentation to synthesize dopamine. The metabolic co-regulation mechanism was further elucidated, demonstrating that the synergistic interaction between GXDK6 and NM1-A2 significantly enhanced dopamine synthesis. Under optimized conditions, dopamine production reached 2019.22 mg/L in a bioreactor. Genome-wide analysis revealed that co-fermentation enriched proteins involved in the conversion of tyrosine to dopamine, including polyphenol oxidase (encoded by gene PPO) and tyrosine decarboxylase (encoded by gene BamfnA) from NM1-A2, as well as cytochrome P450 76AD1 (encoded by gene CYP76AD1) and tyrosine decarboxylase (encoded by gene MgmfnA) from GXDK6. These proteins strengthen the dopamine metabolic pathway, facilitating efficient dopamine expression. Heterologous expression of biosynthetic enzymes indicated that dual-gene expression was more effective in dopamine biosynthesis than individual gene expression, for which the synthesized L-dopa was used to catalyze the synthesis of dopamine. In vitro catalysis with purified PPO showed that 5 mM of tyrosine could be converted to 0.21 mM of L-dopa. This co-fermentation strategy provides a novel theoretical framework for the de novo microbial synthesis of dopamine.