graph TD
    A["L-Tyrosine<br/>Substrate"] --> B["Tyrosine Hydroxylase<br/>(TH)"]
    C["Tetrahydrobiopterin<br/>(BH4)"] --> B
    D["O2 and Fe2+<br/>Cofactors"] --> B
    B --> E["L-DOPA<br/>Intermediate"]
    E --> F["Aromatic L-amino acid<br/>Decarboxylase (AADC)"]
    G["Pyridoxal 5'-phosphate<br/>(PLP)"] --> F
    F --> H["Dopamine<br/>Product"]
    I["GTP Cyclohydrolase I<br/>(GTPCH1)"] --> J["BH4 Biosynthesis<br/>Pathway"]
    K["6-pyruvoyl-tetrahydropterin<br/>Synthase (PTPS)"] --> J
    J --> C
    L["Engineered Probiotic<br/>Bacteria"] --> B
    L --> F
    L --> I
    L --> K
    H --> M["Striatal Dopamine<br/>Restoration"]
    M --> N["Improved Motor<br/>Function"]
    O["Neurodegeneration<br/>Process"] --> P["Dopamine Depletion"]
    P --> Q["Motor Dysfunction<br/>Symptoms"]

    classDef normal fill:#4fc3f7,color:#0d0d1a
    classDef therapeutic fill:#81c784,color:#0d0d1a
    classDef pathology fill:#ef5350,color:#0d0d1a
    classDef outcome fill:#ffd54f,color:#0d0d1a
    classDef molecular fill:#ce93d8,color:#0d0d1a

    class A,C,D,G normal
    class B,F,I,J,K,L therapeutic
    class O,P,Q pathology
    class M,N outcome
    class E,H molecular