algC (P26276, PA5322) — Pseudomonas aeruginosa PAO1 — curation notes

Deep research

• 2026-10-23: just deep-research PSEAE algC --provider perplexity failed
  ("Provider 'perplexity' not available. Available: falcon, openscientist").
  No deep-research file was generated; the review is built from cached primary
  literature and the curated UniProt entry. Additional papers were cached with
  just fetch-pmid (PMIDs 10481091, 11839312, 14725765, 11716469, 16595672,
  16880541, 18690721, 22242625).

Enzymology

• Bifunctional PMM/PGM, monomer of 50 kDa PMID:8050998
• Both reactions on purified enzyme PMID:8050998
• Km values and efficiency [PMID:8050998 "The apparent Km values for M1P and G1P were 17 and 22 microM, respectively."; "the catalytic efficiency for G1P was about twofold higher than that for M1P"]
• Mg2+ requirement PMID:8050998; Mg2+-binding loop in structure PMID:16880541; Zn2+ in crystals gives inactive enzyme PMID:16880541.
• Mechanism: phosphoenzyme at Ser108, bisphosphate intermediate reorients PMID:11716469; processive reorientation PMID:16595672.
• Dual substrate recognition in one site PMID:14725765.
• General base His329 PMID:23517223.
• Four-domain structure, domain 4 closes active site [PMID:11839312 "Residues from all four domains of the protein contribute to the formation of a large active site cleft"; PMID:18690721 "binding of substrates produces a rotation of the C-terminal domain"].

Physiological roles (genetics)

• Alginate: algC identified as the PMM gene of the alginate pathway, AlgR-activated PMID:1903398.
• LPS core and O antigen [PMID:7515870 "did not express lipopolysaccharide (LPS) O side chains or the A-band (common antigen) polysaccharide"; "the synthesis of glucose 1-phosphate is necessary in the biosynthesis of the P. aeruginosa LPS core"].
• Both activities absent in algC mutants PMID:8050998.
• Rhamnolipid PMID:10481091.
• Psl and Pel; precursor checkpoint [PMID:22513190 "AlgC, a key enzyme that provides sugar precursors for the synthesis of alginate and lipopolysaccharides (LPS) is also required for both Psl and Pel production"; "we propose that AlgC is a key checkpoint enzyme"].

Curation decisions

• MF: GO:0004614 and GO:0004615 accepted on all evidence codes; GO:0016868 MODIFY to both.
• GO:0000287 magnesium ion binding accepted (IDA and IEA): one Mg2+ per subunit, structurally resolved, kinetically required.
• Process: direct products are mannose 1-P (-> GDP-mannose via AlgA -> alginate, A-band, Psl) and glucose 1-P (-> UDP-glucose -> LPS outer-core glucose; -> dTDP-rhamnose). Accepted GDP-mannose biosynthesis (GO:0009298), alginate (GO:0042121), LPS core (GO:0009244). Proposed GO:0120530 UDP-alpha-D-glucose biosynthetic process as replacement for GO:1901137. GO:0005975 and GO:0009103 MODIFY to the specific terms the gene already carries.
• O antigen (GO:0009243): KEEP_AS_NON_CORE; the defect is secondary to core truncation (B-band) and to GDP-mannose-derived A-band precursors, upstream of O-antigen assembly.
• Rhamnolipid biosynthesis (GO:0106236) not added as NEW: evidence is necessity (mutant phenotype) for a precursor step; left as a suggested question pending a comparator check against RmlA-D annotation.
• No subcellular location asserted in core functions: no direct localization evidence in cached sources (soluble enzyme expected).