IlvA-I is a full-length, PLP-dependent biosynthetic threonine deaminase that converts L-threonine to 2-oxobutanoate, the entry metabolite for L-isoleucine biosynthesis. It contains the catalytic serine/threonine-dehydratase domain and two C-terminal ACT-like regulatory domains. KT2440 also encodes the closely related IlvA-II, and their relative physiological contributions have not been established.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003941 L-serine ammonia-lyase activity | IEA GO_REF:0000118 | KEEP AS NON CORE | Summary: Serine ammonia-lyase activity is a supported secondary family activity, inferred for this paralog. Reason: Direct recombinant enzyme studies demonstrate L-serine use by biosynthetic IlvA homologs (PMID:30226377, Mycobacterium smegmatis; PMID:30327426, Salmonella enterica). The target retains the biosynthetic Ser/Thr-dehydratase catalytic architecture, supporting the TreeGrafter molecular-activity inference even though its main pathway supplies isoleucine. This is comparative evidence, not a target-specific kinetic measurement or proof of physiological serine flux. Supporting Evidence: PMID:30226377 We show here that in addition to l-threonine, l-allo-threonine and l-serine are also used as substrates by TD PMID:30327426 the enzyme generates both 2AA (from serine) and 2AC (from threonine) |
| GO:0004794 threonine deaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: This is the defining IlvA-I molecular function. Reason: EC 4.3.1.19, RHEA:22108, InterPro:IPR005787, and the full-length ACT-domain architecture support biosynthetic L-threonine deamination. Supporting Evidence: file:PSEPK/ilvA-I/ilvA-I-uniprot.txt Full=L-threonine dehydratase file:PSEPK/ilvA-I/ilvA-I-deep-research-openscientist.md **ilvA-I** (UniProt **Q88HB4**; ordered locus **PP_3446**) of *Pseudomonas putida* KT2440 (PSEPK) encodes a **biosynthetic L-threonine dehydratase** — equivalently a **threonine deaminase (TD)** — classified as **EC 4.3.1.19**. |
| GO:0006520 amino acid metabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: IlvA directly performs amino-acid metabolism. Reason: Its catalysis consumes L-threonine and supplies 2-oxobutanoate for L-isoleucine synthesis. Both the broad amino-acid process and the specific isoleucine biosynthetic process are correct; annotation breadth does not imply excess biological scope. Supporting Evidence: file:PSEPK/ilvA-I/ilvA-I-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+) |
| GO:0006565 L-serine catabolic process | IEA GO_REF:0000118 | UNDECIDED | Summary: Physiological serine breakdown by this KT2440 paralog remains unresolved. Reason: Family enzyme assays support a serine-dehydratase side activity, and PMID:30327426 shows that this chemistry can occur in vivo in a biosynthetic IlvA context. They do not determine the contribution of either KT2440 paralog to physiological serine turnover. The isoleucine role does not exclude such a contribution; quantitative target-specific flux evidence is missing. Supporting Evidence: file:PSEPK/ilvA-I/ilvA-I-deep-research-openscientist.md **Physiological significance of the serine-dehydratase side reaction / 2AA output in KT2440 is untested.** PMID:30327426 These growth defects are due to 2AA generated by the biosynthetic serine/threonine dehydratase (IlvA; EC 4.3.1.19) from serine. |
| GO:0006567 L-threonine catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: The IlvA reaction directly breaks down L-threonine while supplying isoleucine synthesis. Reason: GO:0006567 covers chemical reactions resulting in L-threonine breakdown. Conversion to 2-oxobutanoate and ammonium satisfies that definition. Subsequent use of the carbon skeleton in biosynthesis does not exclude threonine catabolism or require a dedicated energy-generating degradation pathway. Supporting Evidence: file:PSEPK/ilvA-I/ilvA-I-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+) |
| GO:0030170 pyridoxal phosphate binding | IEA GO_REF:0000002 | ACCEPT | Summary: PLP binding is integral to the core deaminase reaction. Reason: The conserved pyridoxal-phosphate-binding catalytic domain and UniProt cofactor assignment support binding the required cofactor. The existence of a more informative reaction term does not make this essential catalytic property non-core. Supporting Evidence: file:PSEPK/ilvA-I/ilvA-I-uniprot.txt InterPro; IPR000634; Ser/Thr_deHydtase_PyrdxlP-BS. |
| GO:1901705 L-isoleucine biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: IlvA-I supplies 2-oxobutanoate to the isoleucine branch. Reason: UniProt assigns Q88HB4 to the single conversion of L-threonine to 2-oxobutanoate in L-isoleucine biosynthesis. Supporting Evidence: file:PSEPK/ilvA-I/ilvA-I-uniprot.txt L-isoleucine biosynthesis file:PSEPK/ilvA-I/ilvA-I-uniprot.txt Reaction=L-threonine = 2-oxobutanoate + NH4(+) |
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)