Bacterial fructose PTS uptake and entry into central carbon catabolism

Scope is abstract within Pseudomonadota: exemplars from Pseudomonas putida KT2440 and Xanthomonas (fused relay) and Escherichia coli K-12 (split relay) delimit family-level roles. The taxon context is limited to the lineages whose relay architectures are modelled. A third architecture, common in Bacillota and Mycoplasmatota, uses general enzyme I and free HPr to phosphorylate an EIIA domain fused to the permease itself (for example Bacillus subtilis FruA, P71012, an EIIABC protein in PTHR30505); it is not modelled here because its relay and permease members have no gene reviews yet. The fused FruB found outside Pseudomonadota, as in Deinococcus, is covered by the concrete fused-relay module. The fused-relay route alone is modelled in detail, with more exemplars and an explicit internal relay step, in the concrete module bacterial_fructose_pts_catabolism. Enterobacterial FPr lacks enzyme I and depends on the general PtsI shared with other PTS sugars. PTNs from source GOA are TreeGrafter or combined-IEA provenance only, except PTN001317471, a PAINT IBD node for the broad phosphofructokinase parent term. Transcriptional regulation, phosphoenolpyruvate supply, and PTS cross-talk are not required catalytic parts of this module. Four module-validator advisories are accepted as intrinsic. (1, 2) The FPr annoton function has no GO identifier, reported once against the FPr gene review and once against PTHR30181:SF3: GO has no term for phosphate transfer from an EIIA histidine to the cognate EIIB, and the broad parent GO:0016772 would only replace these with unreviewed-function advisories. The term is proposed as PTS EIIA-to-EIIB phosphotransferase activity in the proposed_new_terms of the E. coli fruB and P. putida fruB gene reviews. (3) The PTHR30505 family review leaves GO:0022877 scope UNRESOLVED because the family, including subfamily SF0, mixes fructose, fructose-like and mannose PTS components; no PANTHER or NCBIfam family isolates the fructose-specific EIIB-EIIC permeases. (4) The PTHR46566 family review leaves GO:0008662 scope UNRESOLVED because subfamily SF5 also contains tagatose-6-phosphate kinases and SF2 mixes 1- and 6-phosphofructokinases; NCBIfam TIGR03168 likewise spans FruK, PfkB and LacC. The specific activities therefore rest on the reviewed exemplars, not on family membership.

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