| Aspect | Evidence summary | Key citations |
|---|---|---|
| identity | The target matches the requested protein: PP_5309 in *Pseudomonas putida* KT2440 is identified as the likely OxyR homolog, a LysR-family transcriptional regulator involved in oxidative-stress defense. The KT2440 genome paper reports 93% identity over 308 aa to putative OxyR proteins of *P. syringae* strains and ~40% identity to *E. coli* OxyR, supporting correct gene/protein assignment for UniProt Q88C74. | (pqac-00000011, pqac-00000037) |
| family/domains | OxyR belongs to the LysR-type transcriptional regulator (LTTR) family. LTTRs have a conserved N-terminal winged helix-turn-helix DNA-binding domain and a C-terminal effector/redox-sensing and oligomerization domain; OxyR is a redox-sensing LTTR rather than a classical small-molecule-responsive one. | (pqac-00000012, pqac-00000018, pqac-00000035) |
| sensing/activation | In *P. putida*, OxyR is constitutively present and becomes activated by oxidation in response to H2O2, after which the oxidized form binds promoters and activates transcription through RNA polymerase contacts. Broader OxyR literature describes cysteine-dependent disulfide formation/exchange as the biochemical basis of this redox switch. | (pqac-00000004, pqac-00000017, pqac-00000036, pqac-00000042) |
| DNA-binding/promoter architecture | LTTRs typically act through a sliding-dimer/tetramer mechanism with RS/AS1/AS2 promoter sites and ligand- or signal-induced changes in DNA bending. In *P. putida*, OxyR binds palindromic promoter sequences; for trxB, OxyR binds roughly the −200 to −163 region, and RecG-dependent remodeling of palindromic/cruciform DNA promotes productive OxyR tetramer binding. | (pqac-00000018, pqac-00000028, pqac-00000031, pqac-00000038) |
| key regulon targets | The best-supported *P. putida* OxyR targets are peroxide-defense and thiol-redox genes: katA, katB, ahpC, ahpF, and trxB; additional reported OxyR-associated genes include trx-2, hslO, and PP0877. These targets place OxyR at the center of peroxide detoxification and maintenance of cytoplasmic thiol-disulfide balance. | (pqac-00000004, pqac-00000008, pqac-00000021, pqac-00000022, pqac-00000036) |
| operon/genomic context | Two genomic contexts are reported in the retrieved literature: (i) KT2440 genome analysis places PP5309 with exbBD/tonB ferric-siderophore uptake genes; (ii) functional studies in *Pseudomonas* show oxyR can be co-transcribed with recG, and RecG is required for induction of many OxyR targets. Together these findings suggest strain-specific or annotation-context complexity around the locus and caution against oversimplifying local operon structure. | (pqac-00000011, pqac-00000036, pqac-00000037, pqac-00000042) |
| quantitative data | Quantitative observations include ~15-fold H2O2 induction of ahpC/ahpF, and in an oxyR1 background protein abundance increases of ~3.7-fold (KatA), ~10-fold (KatB), ~7.5-fold (AhpF), ~5-fold (TrxB), and ~4–20-fold (AhpC; imprecise estimate). Under paraquat stress, a trxB mutant grew more slowly than wild type (0.56 ± 0.08 h−1 vs 1.03 ± 0.16 h−1). | (pqac-00000005, pqac-00000021, pqac-00000039) |
| localization | OxyR is described as sensing the cytoplasmatic redox state, implying a cytoplasmic transcription factor acting on chromosomal promoters. Its functional outputs regulate mainly cytoplasmic/periplasm-protective antioxidant systems, but the regulator itself is not reported as membrane or extracellular. | (pqac-00000011, pqac-00000037) |
| pathways/biological role | The primary annotated role is transcriptional control of oxidative-stress defense, especially H2O2 detoxification via catalases/peroxiredoxins and redox-homeostasis pathways involving thioredoxin reductase. RecG coupling connects this response to DNA structural remodeling and likely stress-associated DNA repair/transcription coordination. | (pqac-00000004, pqac-00000017, pqac-00000022, pqac-00000036, pqac-00000042) |
| applications/engineering relevance | Recent 2024 LTTR/OxyR work highlights practical relevance in biosensor design, oxidative-stress engineering, and data-driven strain optimization. LTTRs are being developed as transcription-factor biosensors, while OxyR-centered modules and oxyR* variants were used to rebalance oxidative-stress responses in engineered bacteria; meta-analysis of 7,670 ALE mutations across 59 experiments also identified OxyR as a recurrent oxidative-stress engineering target. | (pqac-00000014, pqac-00000024, pqac-00000025, pqac-00000029, pqac-00000043) |
| notes/limitations | Direct *P. putida* KT2440 primary literature for PP_5309 is limited, and some quantitative/mechanistic evidence comes from KT2442 or broader *Pseudomonas* studies. The retrieved evidence supports OxyR as a peroxide-stress regulator, but did not provide strong *P. putida*-specific evidence for direct nitrosative-stress regulation by OxyR; nitrosative roles are better documented in other species. | (pqac-00000020, pqac-00000023, pqac-00000036, pqac-00000039) |


*Table: This table summarizes the functional annotation of *Pseudomonas putida* KT2440 OxyR (UniProt Q88C74; oxyR; PP_5309), including identity, mechanism, regulon, genomic context, quantitative evidence, and current engineering relevance. It is designed as a compact evidence map for downstream reporting or curation.*