ptxD

Summary: Cytosolic localization is compatible with the intracellular KguK-KguD arm but is inherited from TreeGrafter rather than directly shown for Q88HI1.

Reason: Retain the plausible localization as ancillary; pathway order supports intracellular action but does not directly resolve cytosol versus broader cytoplasm.

Summary: This generic term is consistent with a dehydrogenase but lacks reaction specificity.

Reason: GO:0008114 is the appropriate pathway-grounded molecular function.

Summary: The broad chemistry is compatible with KguD but should be replaced by the specific EC 1.1.1.43 term.

Reason: Direct locus genetics and conserved pathway order support phosphogluconate 2-dehydrogenase activity more specifically.

Proposed replacements: phosphogluconate 2-dehydrogenase activity

Summary: Unresolved. Q88HI1 has no experimentally determined substrate, and the KguD assignment used elsewhere in this review is itself an inference from kgu-locus context rather than biochemistry on this protein, so it does not exclude hydroxypyruvate reduction. Family members are commonly promiscuous across 2-oxoacid substrates; needs a Q88HI1 assay.

Reason: Re-review: changed from REMOVE to UNDECIDED. The stated ground was only the absence of a target-specific assay, which is not by itself a refutation of a phylogenetic inference. Q88HI1 carries no experimentally determined substrate: UniProt gives only the EMBL-derived SubName "Phosphonate dehydrogenase" and the generic D-isomer specific 2-hydroxyacid dehydrogenase family (PANTHER PTHR10996:SF283 GLYOXYLATE/HYDROXYPYRUVATE REDUCTASE B, the node this term comes from), while the KguD assignment used in this review is itself an inference from kgu-locus context (PMID:29607620, PMID:39770733). Members of this family are commonly promiscuous across 2-oxoacid substrates, so GO:0016618 can be neither confirmed nor refuted without a Q88HI1 assay. The blinded OpenScientist control run (see the paired GO:0030267 row) recommended adding this term as the second half of a GhrB-type dual activity; its homology and active-site facts were reproduced locally, but it did not weigh the kgu-locus KguD context, so the row stays UNDECIDED.

Summary: Still unresolved after the blinded OpenScientist control run. The run confirmed, and local re-alignment reproduced, that Q88HI1 is a catalytically intact GhrB-subfamily D-2-hydroxyacid dehydrogenase (about 53% identical to E. coli GhrB) and not a phosphite dehydrogenase, so the TreeGrafter placement is sound. But the run did not consider the kgu-locus context, in which PP_3376 is the KguD 2-keto-6-phosphogluconate reductase; glyoxylate reduction may be a side activity of the subfamily-wide active site, but it has never been measured for Q88HI1.

Reason: Re-reviewed against the OpenScientist control report, which recommended retaining GO:0030267 and adding GO:0016618 on the grounds that the nearest characterized homolog is E. coli GhrB (P37666). Verified in this re-review: a BLOSUM62 global alignment gives 53.1% identity of Q88HI1 to GhrB, 40.0% to human GRHPR and 38.4% to phosphite dehydrogenase PtxD (O69054); the PtxD phosphite-pocket Lys76 aligns to Val75 in Q88HI1, while the Arg237/Glu266/His285 triad and the GMGRIG Rossmann motif at position 152 are present. The report's claim of a PtxD Trp314 was not reproduced (O69054 position 314 is Gln). These facts rule out the pseudo-enzyme and mis-placement failure modes, and they support removal of GO:0050609. They do not settle the substrate. The run was blinded to gene context, and KEGG places PP_3376 (K00032, EC 1.1.1.43) immediately downstream of kguT (PP_3377), kguK (PP_3378) and kguE (PP_3379) beside ptxS (PP_3380), the kgu operon whose KguD member reduces 2-keto-6-phosphogluconate (PMID:39770733). GhrB itself is promiscuous (UniProt P37666 also lists 2-ketogluconate reductase, EC 1.1.1.215), so a 2-ketoaldonate reductase physiological role and a glyoxylate side activity are both plausible for this subfamily, but nothing measured on Q88HI1 or a KguD ortholog shows glyoxylate reduction. The analyses agree on the facts and differ on interpretation; the deciding experiment is a substrate panel (2-keto-6-phosphogluconate, glyoxylate, hydroxypyruvate, 2-ketogluconate) with NADPH and NADH on purified Q88HI1.

Summary: The EC mapping follows the legacy ptxD name; no direct Q88HI1 phosphite assay was found.

Reason: The D-isomer-specific 2-hydroxyacid dehydrogenase fold is shared with genuine PtxD and does not discriminate the activities. Removal rests on the kgu-locus/pathway assignment and absence of a Q88HI1 phosphite assay, and is now reinforced by the blinded OpenScientist control run, whose key residue finding was reproduced locally: the PtxD phosphite-binding Lys76 aligns to Val75 in Q88HI1, and Q88HI1 is far closer to GhrB (53%) than to characterized PtxD O69054 (38%). The ptxD symbol and EC 1.20.1.1 come only from the EMBL submitter name.

Summary: The NAD-binding domain supports dinucleotide binding, but Q88HI1 cofactor preference is not established.

Reason: EC 1.1.1.43 is NAD(P)-dependent and InterPro IPR006140 supports an NAD-binding fold; retain this as ancillary pending target-protein cofactor measurements.

Summary: PP_3376 disruption and the ordered kgu pathway place this protein in the 2-ketogluconate loop.

Reason: This process covers the intracellular phosphorylative use of 2-ketogluconate without misclassifying it as a non-phosphorylated reaction.