cpsG (PP_1777) encodes a ManB/CpsG-type phosphomannomutase. Its primary reaction is the magnesium-dependent interconversion of mannose 6-phosphate and mannose 1-phosphate, supplying mannose 1-phosphate for GDP-mannose and downstream cell-envelope carbohydrate biosynthesis. Direct evidence for physiologically relevant phosphoglucomutase activity is absent.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000287 magnesium ion binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: magnesium ion binding is biologically plausible for this enzyme but is ancillary to the more specific catalytic function. Reason: Retain as a supporting/non-core annotation rather than using it as the main functional summary. |
| GO:0004615 phosphomannomutase activity | IEA GO_REF:0000120 | ACCEPT | Summary: phosphomannomutase activity is consistent with the curated UniProt name, EC/family evidence, and the gene product role summarized here. Reason: This is a specific, biologically appropriate annotation for this gene product. |
| GO:0005975 carbohydrate metabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: carbohydrate metabolic process is consistent with the curated UniProt name, EC/family evidence, and the gene product role summarized here. Reason: This is a specific, biologically appropriate annotation for this gene product. |
| GO:0016868 intramolecular phosphotransferase activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: intramolecular phosphotransferase activity is biologically plausible for this enzyme but is ancillary to the more specific catalytic function. Reason: Retain as a supporting/non-core annotation rather than using it as the main functional summary. |
| GO:0009298 GDP-mannose biosynthetic process | ISS file:PSEPK/cpsG/cpsG-deep-research-openscientist.md | NEW | Summary: The phosphomannomutase reaction supplies mannose 1-phosphate for the canonical GDP-mannose pathway; comparative analysis supports a mannose-specialized ManB/CpsG assignment for PP_1777. Supporting Evidence: file:PSEPK/cpsG/cpsG-deep-research-openscientist.md This reaction constitutes the second committed step of the GDP-mannose biosynthetic pathway |
Loading supporting content…
Download this section (compressed HTML)Q: Does PP_1777 have measurable phosphoglucomutase side activity, and which GDP-mannose-derived glycans depend specifically on CpsG rather than AlgC?
Experiment: Compare phosphomannomutase and phosphoglucomutase kinetics for purified PP_1777 and characterize nucleotide-sugar and glycan changes in a cpsG mutant.
Type: comparative enzymology and targeted genetics
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)