prs (PP_0722) encodes ribose-phosphate pyrophosphokinase (PRPP synthase; EC 2.7.6.1), a class I bacterial enzyme that catalyzes the Mg2+-dependent, essentially irreversible transfer of the diphosphoryl group from ATP to ribose-5-phosphate to produce 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) plus AMP. PRPP is a central "activated ribose" branch-point metabolite that supplies ribose-phosphate to purine and pyrimidine nucleotide biosynthesis and salvage, NAD/NADP cofactor biosynthesis, and (in many bacteria) histidine and tryptophan biosynthesis. The enzyme is a cytosolic homohexamer subject to phosphate activation and feedback inhibition by adenine/guanine nucleotides. No KT2440-specific primary characterization of PP_0722 was located; functional annotation is supported at the family/EC level by UniProt and the bacterial PRPP synthase literature.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000287 magnesium ion binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Magnesium binding is a required catalytic cofactor feature. Class I bacterial PRPP synthases require divalent cations including Mg2+, consistent with UniProt's annotation of two Mg(2+) ions per subunit. Reason: Mg2+ binding is essential for catalysis but is a cofactor feature rather than the specific molecular function; the deep research literature confirms class I PRPP synthases require Mg2+ (in addition to MgATP) for activity. Supporting Evidence: file:PSEPK/prs/prs-uniprot.txt Binds 2 Mg(2+) ions per subunit file:PSEPK/prs/prs-goa.tsv GO:0000287 magnesium ion binding file:PSEPK/prs/prs-deep-research-falcon.md class I enzymes require divalent cations, including |
| GO:0002189 ribose phosphate diphosphokinase complex | IEA GO_REF:0000118 | KEEP AS NON CORE | Summary: PRPP synthase assembles into a multimeric complex (UniProt reports a homohexamer). The cellular component annotation is plausible but less informative than the enzyme activity term. Reason: The defining function is best captured by ribose phosphate diphosphokinase activity and PRPP biosynthesis; the homo-oligomeric assembly is supporting context. UniProt reports the subunit as a homohexamer. Supporting Evidence: file:PSEPK/prs/prs-goa.tsv GO:0002189 ribose phosphate diphosphokinase complex file:PSEPK/prs/prs-uniprot.txt SUBUNIT: Homohexamer |
| GO:0004749 ribose phosphate diphosphokinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Ribose phosphate diphosphokinase activity (EC 2.7.6.1) is the exact core molecular function. The enzyme transfers the pyrophosphoryl/diphosphoryl group from ATP to ribose-5-phosphate, producing PRPP and AMP. Reason: UniProt assigns EC 2.7.6.1 and the Rhea reaction (RHEA:15609), and the deep research literature confirms the canonical PRPP synthase reaction (ribose-5-phosphate + ATP -> PRPP + AMP) for the ribose-phosphate pyrophosphokinase family. Supporting Evidence: file:PSEPK/prs/prs-uniprot.txt transfer of pyrophosphoryl group from ATP to 1-hydroxyl file:PSEPK/prs/prs-goa.tsv GO:0004749 ribose phosphate diphosphokinase activity file:PSEPK/prs/prs-deep-research-falcon.md catalyzes the formation of PRPP from ribose-5-phosphate and ATP, producing AMP file:PSEPK/prs/prs-deep-research-falcon.md irreversible diphosphoryl transfer from ATP to ribose-5-phosphate |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Cytoplasm is the expected localization for this soluble central-metabolism enzyme. The deep research literature treats bacterial PRPP synthase as a soluble cytosolic enzyme acting on central metabolites. Reason: Localization is useful context but not the defining function. KT2440-specific localization was not directly measured; cytosolic localization is the most consistent inference and matches the UniProt subcellular location. Supporting Evidence: file:PSEPK/prs/prs-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm file:PSEPK/prs/prs-goa.tsv GO:0005737 cytoplasm file:PSEPK/prs/prs-deep-research-falcon.md soluble cytosolic enzyme |
| GO:0006015 5-phosphoribose 1-diphosphate biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: 5-phosphoribose 1-diphosphate (PRPP) biosynthesis is the direct biological process for Prs, which performs the single-step PRPP biosynthesis route from ribose-5-phosphate (UniPathway UPA00087/UER00172). Reason: UniProt places Prs in the one-step PRPP biosynthesis route from ribose-5-phosphate, and the deep research literature describes the PRPP-synthesizing reaction (R5P -> PRPP) as the enzyme's direct role. Supporting Evidence: file:PSEPK/prs/prs-uniprot.txt 5-phospho-alpha-D-ribose 1-diphosphate from file:PSEPK/prs/prs-goa.tsv GO:0006015 5-phosphoribose 1-diphosphate biosynthetic process file:PSEPK/prs/prs-deep-research-falcon.md diphosphoryl transfer from ATP to ribose-5-phosphate (R5P) to produce |
| GO:0006164 purine nucleotide biosynthetic process | IEA GO_REF:0000118 | KEEP AS NON CORE | Summary: Purine nucleotide biosynthesis is a downstream use of the PRPP that Prs produces, rather than Prs's direct reaction. PRPP is a central branch-point metabolite required for purine and pyrimidine nucleotide biosynthesis and salvage. Reason: PRPP supplies purine biosynthesis, so the involvement is real, but the specific direct process (PRPP biosynthesis, GO:0006015) is the core BP. The deep research confirms PRPP is required for purine and pyrimidine nucleotide biosynthesis. Supporting Evidence: file:PSEPK/prs/prs-goa.tsv GO:0006164 purine nucleotide biosynthetic process file:PSEPK/prs/prs-deep-research-falcon.md Purine and pyrimidine nucleotide biosynthesis |
| GO:0009156 ribonucleoside monophosphate biosynthetic process | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Ribonucleoside monophosphate biosynthesis is broader and downstream of Prs's direct PRPP synthesis; Prs only supplies the PRPP precursor. Reason: GO:0006015 (PRPP biosynthesis) is the more specific direct biological process. The deep research describes PRPP as a precursor metabolite for nucleotide biosynthesis rather than Prs directly performing nucleoside monophosphate synthesis. Supporting Evidence: file:PSEPK/prs/prs-goa.tsv GO:0009156 ribonucleoside monophosphate biosynthetic process file:PSEPK/prs/prs-deep-research-falcon.md supplies ribose-phosphate to multiple biosynthetic pathways |
| GO:0009165 nucleotide biosynthetic process | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Nucleotide biosynthetic process is too broad for Prs, which directly synthesizes the PRPP precursor rather than nucleotides themselves. Reason: Prs directly synthesizes PRPP, a precursor for nucleotide biosynthesis; GO:0006015 is the specific process. The deep research frames PRPP as a central activated-ribose donor feeding nucleotide pathways. Supporting Evidence: file:PSEPK/prs/prs-goa.tsv GO:0009165 nucleotide biosynthetic process file:PSEPK/prs/prs-deep-research-falcon.md central activated ribose donor |
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Download this section (compressed HTML)Q: How is KT2440 Prs allosterically regulated by phosphate activation and nucleotide pools (AMP/ADP/GDP) during carbon-source shifts?
Q: Does P. putida KT2440 Prs assemble into filamentous cytoophidia, and if so does filamentation modulate its sensitivity to allosteric inhibition as shown for other bacterial PRPP synthases?
Experiment: Measure Prs kinetics, phosphate activation, and nucleotide (AMP/ADP/GDP) inhibition with purified KT2440 enzyme, coupled to intracellular PRPP/nucleotide profiling in prs perturbation strains.
Type: enzyme regulation and metabolomics assay
Experiment: Test for native filamentation/cytoophidia formation of KT2440 Prs by fluorescence microscopy of tagged Prs and cryo-EM of purified enzyme under different ligand (ATP/ADP/Pi) conditions.
Type: structural and cell biology assay
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