apaH encodes a symmetrical bis(5'-nucleosyl)-tetraphosphatase that hydrolyzes diadenosine tetraphosphate to ADP.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008803 bis(5'-nucleosyl)-tetraphosphatase (symmetrical) activity | IEA GO_REF:0000120 | ACCEPT | Summary: The Ap4A hydrolase activity annotation matches the curated UniProt catalytic function. Reason: UniProt assigns EC 3.6.1.41 and the Rhea reaction for hydrolysis of diadenosine tetraphosphate to ADP. Supporting Evidence: file:PSEPK/apaH/apaH-uniprot.txt Hydrolyzes diadenosine 5',5'''-P1,P4-tetraphosphate to yield file:PSEPK/apaH/apaH-uniprot.txt Reaction=P(1),P(4)-bis(5'-adenosyl) tetraphosphate + H2O file:PSEPK/apaH/apaH-goa.tsv GO:0008803 bis(5'-nucleosyl)-tetraphosphatase file:PSEPK/apaH/apaH-deep-research-falcon.md **ApaH**: typically performs **symmetric cleavage** of Ap4A to generate **two ADP molecules**. file:PSEPK/apaH/apaH-deep-research-falcon.md The UniProt entryβs βsymmetricalβ bis(5β²-nucleosyl)-tetraphosphatase assignment is consistent with the **ApaH family biochemical mode**. |
| GO:0016787 hydrolase activity | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: Hydrolase activity is true but too generic for ApaH. Reason: The specific bis(5'-nucleosyl)-tetraphosphatase activity captures the enzyme function, so the broad hydrolase parent should not be used as the informative annotation. Supporting Evidence: file:PSEPK/apaH/apaH-uniprot.txt EC=3.6.1.41 file:PSEPK/apaH/apaH-goa.tsv GO:0016787 hydrolase activity file:PSEPK/apaH/apaH-deep-research-falcon.md Bis(5β²-nucleosyl)-tetraphosphatase (symmetrical) / Ap4A hydrolase (**EC 3.6.1.41**) catalyzing **Ap4A β ADP + ADP**. |
| GO:0015967 diadenosine tetraphosphate catabolic process | ISS file:PSEPK/apaH/apaH-deep-research-falcon.md | NEW | Summary: Falcon deep research places ApaH in intracellular Ap4A/Ap4N homeostasis, where loss of the enzyme elevates intracellular Ap4A. This biological process is the direct counterpart of the symmetric Ap4A hydrolase activity but is absent from the GOA (MF-only IEA terms). Reason: Adds the missing biological-process aspect for Ap4A breakdown, supported by ApaH-family evidence across Pseudomonas and E. coli. Supporting Evidence: file:PSEPK/apaH/apaH-deep-research-falcon.md Intracellular Ap4A/Ap4N homeostasis; stress-responsive nucleotide signaling file:PSEPK/apaH/apaH-deep-research-falcon.md genetic loss of Ap4A degradation** (including **ΞapaH**) elevates intracellular Ap4A |
| GO:0005737 cytoplasm | ISS file:PSEPK/apaH/apaH-deep-research-falcon.md | NEW | Summary: No GOA cellular-component annotation exists for apaH. ApaH acts on intracellular Ap4A pools and is inferred to function in the cytosol/cytoplasm. Falcon flags this as a best inference rather than a directly measured localization for KT2440. Reason: Adds the missing cellular-component aspect; the cytoplasmic localization is an inference by homology from Pseudomonas studies of intracellular Ap4A pools. Supporting Evidence: file:PSEPK/apaH/apaH-deep-research-falcon.md imply that ApaH functions primarily in the **cytosol** file:PSEPK/apaH/apaH-deep-research-falcon.md **Cytosolic** enzyme controlling **intracellular** Ap4A pools. |
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Download this section (compressed HTML)Q: Is ApaH activity in KT2440 regulated by stress conditions that alter intracellular Ap4A levels?
Experiment: Measure Ap4A and ADP levels in wild-type and apaH knockout strains under growth and stress conditions.
Type: targeted nucleotide metabolite profiling
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