aroC encodes chorismate synthase (CS; EC 4.2.3.5), the enzyme that catalyzes the seventh and final step of the shikimate pathway. It converts 5-enolpyruvylshikimate-3-phosphate (EPSP) into chorismate via an anti-1,4 (trans) elimination of the C-3 phosphate and the C-6 proR hydrogen, introducing a second double bond into the ring system. The reaction requires reduced flavin mononucleotide (FMNH2) as an essential cofactor, even though the overall transformation involves no net change in redox state; like other bacterial monofunctional chorismate synthases, the enzyme relies on an external supply of reduced FMN rather than reducing FMN itself. Chorismate is the central branch-point metabolite of aromatic metabolism, serving as the common precursor for the aromatic amino acids phenylalanine, tyrosine, and tryptophan, as well as for folate (via para-aminobenzoate), ubiquinone/menaquinone, and other aromatic metabolites. The protein belongs to the chorismate synthase family, assembles as a homotetramer, and acts as a soluble cytosolic enzyme of central metabolism.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004107 chorismate synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Core molecular function. AroC is a chorismate synthase (EC 4.2.3.5), as established by the HAMAP rule MF_00300, conserved family membership (IPR000453, PF01264, TIGR00033), and mapping to RHEA:21020. This directly represents the gene's primary catalytic activity. |
| GO:0005829 cytosol | IEA GO_REF:0000118 | KEEP AS NON CORE | Summary: Chorismate synthase catalyzes a soluble step of central aromatic metabolism and has no membrane-targeting features, consistent with a cytosolic localization. This is a reasonable IEA/TreeGrafter inference for a bacterial metabolic enzyme. Bacteria lack the GO cytosol/cytoplasm distinction relevant in eukaryotes, but the term is acceptable as-is; it is not a core functional annotation. |
| GO:0009073 aromatic amino acid family biosynthetic process | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Chorismate produced by AroC is the direct precursor of phenylalanine, tyrosine, and tryptophan, so AroC is correctly placed in aromatic amino acid biosynthesis. This is a valid biological-process annotation, though it is broader than the gene's most specific role (chorismate biosynthesis), and chorismate also feeds non-amino-acid pathways (folate, ubiquinone). Retained as a supporting/non-core process annotation. (Note: GOA label text "aromatic amino acid biosynthetic process" is the curated synonym; the canonical GO:0009073 label is "aromatic amino acid family biosynthetic process".) |
| GO:0009423 chorismate biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Most specific and accurate biological-process annotation: AroC catalyzes the terminal (step 7/7) reaction of chorismate biosynthesis (UniPathway UPA00053, UER00090). This is the core process for the gene. |
| GO:0010181 FMN binding | IEA GO_REF:0000118 | ACCEPT | Summary: Chorismate synthase requires and binds reduced FMN (FMNH2) as an essential cofactor for catalysis; the UniProt record annotates multiple FMN-binding residues (125-127, 237-238, 277, 292-296, 318). FMN binding is well supported and integral to the catalytic mechanism, so this is accepted as a genuine (though accessory-to-the-MF) molecular function annotation. |
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