| Aspect | Finding | Evidence/interpretation |
|---|---|---|
| Gene/protein identity | HglS in *Pseudomonas putida* KT2440 corresponds to PP_5260, also called YdcJ; it is a DUF1338/HGLS-family enzyme assigned as 2-hydroxyglutarate synthase / 2-oxoadipate dioxygenase-decarboxylase (pqac-00000000, pqac-00000006) | Identity matches the UniProt target context and the primary 2019 biochemical/genetic study (pqac-00000000, pqac-00000006) |
| Immediate substrate | HglS acts on 2-oxoadipate (2OA), an intermediate in lysine catabolism downstream of L-2-aminoadipate transamination (pqac-00000000, pqac-00000004) | In vitro enzyme assays and pathway reconstruction place 2OA directly upstream of HglS (pqac-00000000, pqac-00000004, pqac-00000008) |
| Immediate product | HglS converts 2OA to D-2-hydroxyglutarate (D-2HG), preserving stereochemical separation from L-2HG generated in the L-lysine branch (pqac-00000000, pqac-00000002, pqac-00000003) | Product identity and D-stereochemistry were supported by LC-TOF/HPLC comparison to standards and a D-2HG-specific coupled assay (pqac-00000000, pqac-00000004) |
| Downstream metabolism | D-2HG produced by HglS is proposed to be oxidized by PP_4493 en route to central metabolism / the TCA cycle, whereas LhgO is noted as L-2HG-specific and therefore not the appropriate downstream enzyme for HglS product (pqac-00000002, pqac-00000003) | This is a key pathway-disambiguation point: HglS feeds the D-2HG branch, not the L-2HG/LhgO branch (pqac-00000002, pqac-00000003) |
| Pathway role | HglS links 2OA catabolism to lysine utilization, functioning in the D-lysine/L-lysine catabolic network that connects lysine degradation to central metabolism (pqac-00000000, pqac-00000006) | The study describes HglS as filling a missing step in *P. putida* lysine metabolism (pqac-00000000, pqac-00000006) |
| Phenotype of loss | A ΔPP_5260 mutant cannot grow on either lysine isomer, indicating HglS is required for efficient lysine catabolism in vivo (pqac-00000000, pqac-00000004) | Strong genetic evidence that the enzyme is functionally important rather than merely redundant (pqac-00000000, pqac-00000004) |
| Omics/regulation: proteomics | PP_5260/YdcJ abundance increases when cells are grown on L-lysine, D-lysine, or 2-aminoadipate relative to glucose, consistent with metabolite-responsive regulation of the lysine catabolic module (pqac-00000001, pqac-00000002, pqac-00000006) | Supports inducible expression tied to pathway substrates/intermediates rather than constitutive housekeeping expression (pqac-00000001, pqac-00000002) |
| Omics/regulation: broader network | The lysine-catabolic genes were reported to be highly sensitive to pathway metabolites, and sigma factor RpoX was required for fitness on D-lysine, suggesting higher-level regulatory control connected to this pathway (pqac-00000002, pqac-00000006) | RpoX is not shown to directly regulate *hglS*, but the phenotype implicates pathway-level transcriptional regulation during D-lysine use (pqac-00000002) |
| Genomic/phylogenetic context | DUF1338/HglS homologs often colocalize with amino-acid catabolic enzymes in bacterial genomes, supporting a catabolic metabolic role beyond *P. putida* (pqac-00000007) | Comparative genomics strengthens the pathway assignment, although it does not replace direct biochemistry (pqac-00000007) |
| Cellular localization | No direct localization experiment was reported in the extracted evidence; because HglS acts on soluble metabolic intermediates (2OA, D-2HG) and was purified as a metal-dependent enzyme without membrane features, the most defensible assignment is a cytosolic enzyme (inference) (pqac-00000000, pqac-00000004, pqac-00000005) | This should be treated as a bioinformatic/biochemical inference rather than direct localization evidence (pqac-00000005) |


*Table: This table summarizes the metabolic context, downstream connections, phenotypes, regulatory signals, and localization inference for HglS (PP_5260/YdcJ) in *Pseudomonas putida* KT2440. It is useful for tying the enzyme’s biochemical activity to its physiological role in lysine catabolism.*