mazG (PP_1657) encodes a soluble tandem-domain nucleoside-triphosphate pyrophosphohydrolase. Q88MB7 belongs to the canonical bacterial MazG family, whose characterized members hydrolyze nucleoside triphosphates to the corresponding nucleoside monophosphates and diphosphate. This activity is consistent with nucleotide-pool quality control and turnover. The gene lies immediately downstream of relA in KT2440, but a specific role for Q88MB7 in the stringent or stress response has not been demonstrated experimentally.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006203 dGTP catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: dGTP hydrolysis is consistent with the broad substrate range of canonical MazG enzymes. Reason: Q88MB7 is assigned to the same tandem-domain PANTHER subfamily as biochemically characterized E. coli MazG. The latter accommodates all eight canonical ribo- and deoxyribonucleoside triphosphates, supporting the TreeGrafter dGTP-catabolism transfer. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0006203 dGTP catabolic process file:PSEPK/mazG/mazG-uniprot.txt DR PANTHER; PTHR30522:SF0; NUCLEOSIDE TRIPHOSPHATE PYROPHOSPHOHYDROLASE; 1. PMID:18353782 hydrolyzes all canonical nucleoside triphosphates |
| GO:0006950 response to stress | IEA GO_REF:0000117 | UNDECIDED | Summary: A stress-response role is plausible but has not been established for Q88MB7. Reason: E. coli MazG affects survival during nutritional stress, and PP_1657 is adjacent to relA in KT2440. However, the annotation is a broad ARBA transfer, and no P. putida experiment was identified that connects Q88MB7 activity to a defined stress response. The conserved catalytic function alone does not establish this organism-specific physiological role. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0006950 response to stress PMID:18353782 In vivo nutrient starvation experiments show that the C terminus NTPase activity is responsible for the regulation of bacterial cell survival under nutritional stress. file:projects/P_PUTIDA/data/psepk_gene_list.tsv relA false Q88MB8 file:PSEPK/mazG/mazG-deep-research-openscientist.md a direct effect of *P. putida* MazG on ppGpp levels has not been measured |
| GO:0046047 TTP catabolic process | IEA GO_REF:0000118 | REMOVE | Summary: The ribothymidine-triphosphate process is not supported by canonical MazG substrate evidence. Reason: GO:0046047 is defined for ribosylthymine triphosphate, whereas the canonical deoxythymidine substrate is represented separately by GO:0046076 and is already present on Q88MB7. The family evidence supports the eight standard ribo- and deoxyribonucleoside triphosphates, not the unusual ribothymidine nucleotide. This TreeGrafter term appears to conflate TTP with dTTP. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0046047 TTP catabolic process file:PSEPK/mazG/mazG-goa.tsv GO:0046076 dTTP catabolic process PMID:18353782 all eight canonical NTPs as substrates |
| GO:0046052 UTP catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: UTP hydrolysis is consistent with the broad substrate range of canonical MazG enzymes. Reason: Q88MB7 has the canonical tandem MazG architecture, and the characterized E. coli family member hydrolyzes all canonical nucleoside triphosphates, including UTP. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0046052 UTP catabolic process PMID:18353782 hydrolyzes all canonical nucleoside triphosphates |
| GO:0046061 dATP catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: dATP hydrolysis is consistent with the broad substrate range of canonical MazG enzymes. Reason: The exact MazG subfamily and tandem-domain architecture support transfer of the canonical deoxyribonucleoside-triphosphate substrate range. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0046061 dATP catabolic process PMID:18353782 all eight canonical NTPs as substrates |
| GO:0046076 dTTP catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: dTTP hydrolysis is consistent with the broad substrate range of canonical MazG enzymes. Reason: The exact MazG subfamily and tandem-domain architecture support transfer of the canonical deoxyribonucleoside-triphosphate substrate range. This is the appropriate thymidine-nucleotide process term for the canonical deoxyribonucleotide substrate. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0046076 dTTP catabolic process PMID:18353782 all eight canonical NTPs as substrates |
| GO:0046081 dUTP catabolic process | IEA GO_REF:0000118 | ACCEPT | Summary: dUTP hydrolysis is consistent with the broad substrate range of canonical MazG enzymes. Reason: The exact MazG subfamily and tandem-domain architecture support transfer of the canonical deoxyribonucleoside-triphosphate substrate range. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0046081 dUTP catabolic process PMID:18353782 all eight canonical NTPs as substrates |
| GO:0047429 nucleoside triphosphate diphosphatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Broad nucleoside-triphosphate diphosphatase activity is the core MazG molecular function. Reason: Q88MB7 contains two MazG-like domains and belongs to the canonical MazG PANTHER subfamily. Structural and biochemical work on the E. coli member establishes hydrolysis of canonical NTPs to NMP and diphosphate, matching this broad GO term. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0047429 nucleoside triphosphate diphosphatase activity file:PSEPK/mazG/mazG-uniprot.txt DR Pfam; PF03819; MazG; 2. PMID:18353782 MazG is a nucleoside triphosphate pyrophosphohydrolase that hydrolyzes all canonical nucleoside triphosphates. file:PSEPK/mazG/mazG-deep-research-openscientist.md 56.7 % identical (74.7 % similar) to the biochemically and structurally characterized *Escherichia coli* MazG |
| GO:0047693 ATP diphosphatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ATP-to-AMP pyrophosphohydrolysis is a supported substrate-specific instance of the broad MazG activity. Reason: UniProt maps Q88MB7 to EC 3.6.1.8 and the exact ATP + water to AMP + diphosphate Rhea reaction. ATP is also among the canonical substrates accommodated by the characterized tandem-domain MazG active site. Supporting Evidence: file:PSEPK/mazG/mazG-goa.tsv GO:0047693 ATP diphosphatase activity file:PSEPK/mazG/mazG-uniprot.txt Reaction=ATP + H2O = AMP + diphosphate + H(+) PMID:18353782 MazG-ATP complex structure |
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Download this section (compressed HTML)Q: Does Q88MB7 regulate canonical, damaged, or alarmone nucleotide pools during nutrient stress in KT2440?
Experiment: Purify Q88MB7 and measure kinetics across canonical and oxidized NTPs and (p)ppGpp, then compare nucleotide pools and starvation survival in mazG, relA, and combined mutants.
Type: biochemical and physiological analysis
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