Bacterial Enzyme-Mediated Dopamine Precursor Synthesis

**Molecular Mechanism and Rationale** The engineered probiotic approach leverages the direct biosynthesis of L-3,4-dihydroxyphenylalanine (L-DOPA) through bacterial expression of two critical enzymes in the dopamine synthesis pathway: tyrosine hydroxylase (TH) and aromatic L-amino acid decarboxylase (AADC). Tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, catalyzes the hydroxylation of L-tyrosine to L-DOPA using tetrahydrobiopterin (BH4) as a cofactor, molecular oxy...