aroH (PP_1866) encodes a class-II (type-II) 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHP synthase / DAH7PS; EC 2.5.1.54) in Pseudomonas putida KT2440. The enzyme catalyzes the aldol-like condensation of phosphoenolpyruvate (PEP) and D-erythrose 4-phosphate (E4P), with release of phosphate, to form 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP). This is the first committed step of the shikimate pathway, which ultimately produces chorismate, the branch-point precursor for the aromatic amino acids (phenylalanine, tyrosine, tryptophan) and many other aromatic metabolites. Class-II DAH7PS enzymes adopt a (beta/alpha)8 TIM-barrel fold and require a divalent metal cation for catalysis; the UniProt record for this protein indicates activity with manganese, cobalt or cadmium ions, with one cation bound per subunit. In bacterial DAHP-synthase nomenclature, AroH is conventionally the tryptophan-sensitive isoenzyme, although the regulatory properties of this specific P. putida protein have not been characterized experimentally. As a soluble central-metabolism enzyme acting on cytosolic substrates, AroH is expected to function in the cytoplasm.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003849 3-deoxy-7-phosphoheptulonate synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Core molecular function. The protein belongs to the class-II DAHP synthase family (RuleBase RU363071; InterPro IPR002480/PF01474; TIGR01358 DAHP_synth_II) and the UniProt catalytic-activity record (Rhea:14717, EC 2.5.1.54) describes condensation of PEP + E4P + H2O to DAHP + phosphate, exactly matching this GO term. Reason: This term precisely captures the enzymatic activity of a class-II DAHP synthase. The assignment is strongly supported by sequence/family evidence (InterPro, RuleBase, NCBIfam TIGR01358) and conserved PEP- and metal-binding residues annotated in UniProt. This is the gene's core molecular function. Supporting Evidence: file:PSEPK/aroH/aroH-deep-research-falcon.md AroH is a DAH7PS catalyzing PEP + E4P -> DAHP/DAH7P and feeding the shikimate pathway; best-supported assignment is class-II / type-II DAH7PS (TIM-barrel fold, conserved metal-binding site), compatible with the UniProt/InterPro/Pfam context for Q88LR3 (PF01474 / DAHP_synth_2). No direct biochemical characterization of P. putida KT2440 AroH was found, so this is family/sequence-level inference. |
| GO:0009073 aromatic amino acid family biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: Correct biological process. DAHP synthase catalyzes the first committed step of the shikimate pathway, which feeds chorismate biosynthesis and the downstream aromatic amino acid (Phe/Tyr/Trp) biosynthetic branches. Reason: This is the canonical pathway role of a DAHP synthase and is consistent with the molecular function annotation. The term is appropriate and represents a core biological process for this gene. (The GOA stub used the label "aromatic amino acid biosynthetic process"; the current GO label for GO:0009073 is "aromatic amino acid family biosynthetic process" and is used here.) |
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