Glucose-6-phosphate 1-dehydrogenase isozyme of Pseudomonas putida KT2440 (ordered locus PP_5351), corresponding to the minor zwfC/G6PDH-C paralog. Sequence and family annotations support canonical glucose-6-phosphate dehydrogenase chemistry with NADP binding, but the best KT2440 experimental synthesis indicates that zwfA and zwfB carry most of the detectable G6PDH activity under the tested conditions. Accordingly, this gene is best curated as a bona fide cytosolic G6PDH isozyme with limited or condition-specific physiological contribution compared with the other two paralogs.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004345 glucose-6-phosphate dehydrogenase activity | IEA GO_REF:0000120 | ACCEPT | Summary: This is the most specific and informative molecular-function annotation for Q88C32. UniProt identifies the protein as glucose-6-phosphate dehydrogenase, and the KT2440 isozyme study shows that the strain carries three distinct G6PDH enzymes with different cofactor preferences. Even if PP_5351 is not the dominant in vivo isozyme, the specific catalytic activity itself is still the correct function for this gene product. Reason: The annotation captures the exact catalytic activity of the protein. The evidence argues for a minor or condition-specific role, but not for removal of the G6PDH molecular function itself. Supporting Evidence: file:PSEPK/zwf/zwf-uniprot.txt RecName: Full=Glucose-6-phosphate 1-dehydrogenase ... EC=1.1.1.49 file:PSEPK/zwf/zwf-notes.md The key KT2440 isozyme paper shows that the strain carries three G6PDH isozymes with different cofactor specificities file:PSEPK/zwf/zwf-deep-research-openscientist.md PP_5351 (*zwf*/Q88C32) is definitively **glucose-6-phosphate 1-dehydrogenase** |
| GO:0016614 oxidoreductase activity, acting on CH-OH group of donors | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: This parent oxidoreductase term is technically compatible with a glucose-6-phosphate dehydrogenase, but it is much less informative than the specific catalytic term already present in the annotation set. Reason: GO:0004345 already captures the exact activity. Retaining this broader oxidoreductase term adds redundancy without improving biological precision. |
| GO:0050661 NADP binding | IEA GO_REF:0000120 | ACCEPT | Summary: NADP binding is consistent with both the UniProt family annotation and the 2021 isozyme study, which concludes that the KT2440 G6PDH isozymes have distinct cofactor specificities. For PP_5351, this is an informative molecular-property annotation rather than a vague binding over-annotation. Reason: Cofactor specificity is central to how the different KT2440 G6PDH isozymes partition redox functions. For this paralog, NADP binding is specific and useful. Supporting Evidence: file:PSEPK/zwf/zwf-uniprot.txt DR GO; GO:0050661; F:NADP binding file:PSEPK/zwf/zwf-notes.md the strain carries three G6PDH isozymes with different cofactor specificities |
| GO:0006006 glucose metabolic process | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: This broad process assignment is plausible by homology, but the best KT2440 evidence does not support PP_5351 as a major contributor to glucose catabolism. The main experimentally supported glucose-processing G6PDH activity in KT2440 is carried by zwfA, with zwfB also contributing more than this paralog. Reason: Assigning the generic glucose metabolic process to this specific paralog overstates the available evidence for its physiological importance. Supporting Evidence: file:PSEPK/zwf/zwf-notes.md the isoforms encoded by zwfA and zwfB carry most of the activity file:PSEPK/zwf/zwf-deep-research-openscientist.md minor, low-flux isozyme |
| GO:0006098 pentose-phosphate shunt | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: G6PDH chemistry connects directly to the oxidative pentose-phosphate branch, but for PP_5351 the current KT2440 evidence supports only a minor or poorly expressed isozyme. The process term is therefore too strong as a gene-specific statement for this paralog. Reason: The process assignment is inferred from enzyme class rather than a clear paralog-specific role in vivo. Supporting Evidence: file:PSEPK/zwf/zwf-notes.md the isoforms encoded by zwfA and zwfB carry most of the activity file:PSEPK/zwf/zwf-deep-research-openscientist.md minor, low-flux isozyme |
| GO:0009051 pentose-phosphate shunt, oxidative branch | IEA GO_REF:0000118 | MARK AS OVER ANNOTATED | Summary: This is an even more pathway-committed version of the same process inference. For PP_5351, the current evidence base is insufficient to treat this paralog as a core oxidative pentose-phosphate enzyme in vivo. Reason: The annotation likely reflects family-level pathway propagation rather than paralog-specific physiological evidence. Supporting Evidence: file:PSEPK/zwf/zwf-notes.md the isoforms encoded by zwfA and zwfB carry most of the activity file:PSEPK/zwf/zwf-deep-research-openscientist.md minor, low-flux isozyme |
| GO:0005829 cytosol | IEA GO_REF:0000118 | ACCEPT | Summary: Cytosolic localization is consistent with the catalytic role of a soluble glucose-6-phosphate dehydrogenase acting on phosphorylated sugar intermediates, and UniProt also places the protein in the cytosol. Reason: This localization is compatible with both enzyme family expectations and the curated UniProt record, and there is no evidence for secretion or a membrane-confined role. Supporting Evidence: file:PSEPK/zwf/zwf-uniprot.txt DR GO; GO:0005829; C:cytosol |
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Download this section (compressed HTML)Q: Under which stress or nutrient conditions is PP_5351/zwfC actually expressed strongly enough to carry meaningful flux?
Suggested experts: Pablo IvΓ‘n Nikel, Daniel Christoph Volke
Q: Does zwfC specialize in redox balancing under conditions where zwfA and zwfB are insufficient, or is it becoming dispensable in KT2440?
Suggested experts: Pablo IvΓ‘n Nikel, Daniel Christoph Volke
Experiment: Measure zwf, zwfA, and zwfB transcript levels and promoter activity across glucose, gluconate, ribose, oxidative stress, and redox-imbalancing conditions to identify contexts that induce PP_5351.
Type: promoter reporter and RNA-seq
Experiment: Compare WT, Ξzwf, and combinatorial zwf paralog mutants by 13C flux analysis and intracellular NADPH/NADH measurements under oxidative and sugar-shift conditions to test whether PP_5351 has a backup redox-balancing role.
Type: fluxomics and redox phenotyping
Experiment: Purify the PP_5351 enzyme from KT2440 or recombinant expression and determine kinetic constants with NADP and NAD for glucose-6-phosphate to quantify how much catalytic capacity remains relative to ZwfA and ZwfB.
Type: enzymology
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