tsaA (locus PP_1084) encodes a cytoplasmic AhpC/Prx1-family (typical 2-Cys) thioredoxin peroxidase/peroxiredoxin (PpPrx). Its core role is thioredoxin-dependent reduction and detoxification of hydrogen peroxide (and, by subfamily inference, organic hydroperoxides), contributing to cellular oxidant detoxification and redox stress protection in KT2440. The directly studied KT2440 protein additionally displays a redox-dependent molecular chaperone (holdase) activity; it self-associates into high-molecular-weight oligomers that suppress protein aggregation, and oxidative conditions drive a structural switch toward low-molecular-weight peroxidase-active forms, constituting a peroxidase/chaperone functional switch (PMID:21104173, PMID:26278368).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0004601
peroxidase activity
|
IEA
GO_REF:0000117 |
ACCEPT |
Summary: Peroxidase activity is correct for this thiol-specific peroxidase, although the peroxiredoxin/thioredoxin peroxidase terms are more informative.
Reason: UniProt describes reduction of hydrogen peroxide and organic hydroperoxides, supporting peroxidase activity.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
|
|
GO:0005737
cytoplasm
|
IEA
GO_REF:0000117 |
ACCEPT |
Summary: Cytoplasm is directly supported by the UniProt subcellular-location statement and corroborated by a PSORTb cytoplasmic prediction for KT2440 PP_1084 in the falcon report.
Reason: The protein is annotated as cytoplasmic and has no evidence for another compartment; a PSORTb prediction independently places PP_1084/PpPrx in the cytoplasm.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
PSORTb-based prediction placed PP1084/PpPrx in the **cytoplasm**, aligning with expected localization for a thioredoxin-coupled peroxide detox enzyme operating on intracellular peroxides and protein thiol redox balance
|
|
GO:0005829
cytosol
|
IEA
GO_REF:0000118 |
KEEP AS NON CORE |
Summary: Cytosol is compatible with the cytoplasmic location, but it is not the core function. A PSORTb cytoplasmic prediction for KT2440 PP_1084 in the falcon report is consistent with this assignment.
Reason: Retain as a non-core location annotation in the bacterial cytoplasm/cytosol context.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
PSORTb-based prediction placed PP1084/PpPrx in the **cytoplasm**, aligning with expected localization for a thioredoxin-coupled peroxide detox enzyme operating on intracellular peroxides and protein thiol redox balance
|
|
GO:0006979
response to oxidative stress
|
IEA
GO_REF:0000120 |
KEEP AS NON CORE |
Summary: Response to oxidative stress is supported but broad relative to direct peroxide detoxification. The falcon report notes the protein was enriched after oxidative treatments (H2O2, gamma rays) in KT2440.
Reason: The protein protects against oxidative stress through peroxidase activity; the direct detoxification process terms are more specific.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
PP1084/PpPrx was discovered among **disulfide-bonded proteins** enriched after **oxidative treatments (H2O2, gamma rays)** in KT2440, consistent with involvement in oxidative-stress response and thiol redox homeostasis
|
|
GO:0008379
thioredoxin peroxidase activity
|
IEA
GO_REF:0000118 |
ACCEPT |
Summary: Thioredoxin peroxidase activity is the specific catalytic role of TsaA. The falcon report confirms that the directly characterized KT2440 protein (PpPrx) is a thioredoxin-dependent peroxidase assayed with a thioredoxin-coupled system, consistent with this term.
Reason: The UniProt entry identifies the protein as a thiol-specific/thioredoxin peroxidase that reduces peroxides, and the directly studied KT2440 protein PpPrx (PP_1084) is experimentally a thioredoxin-dependent peroxidase.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
locus **PP_1084** encodes a cytosolic **AhpC/Prx1-family (typical 2-Cys) peroxiredoxin**, experimentally characterized as a **thioredoxin-dependent peroxidase** that can also act as a **stress-responsive molecular chaperone** via oligomerization-dependent functional switching
|
|
GO:0016209
antioxidant activity
|
IEA
GO_REF:0000002 |
MARK AS OVER ANNOTATED |
Summary: Antioxidant activity is true in a broad sense but is less informative than peroxiredoxin and thioredoxin peroxidase activity.
Reason: The annotation should prioritize the direct enzymatic activity rather than a generic antioxidant-function parent.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
|
|
GO:0016491
oxidoreductase activity
|
IEA
GO_REF:0000002 |
MARK AS OVER ANNOTATED |
Summary: Oxidoreductase activity is a broad parent that adds little beyond the specific peroxiredoxin/peroxidase terms.
Reason: The specific peroxide-reduction terms are available and should carry the functional interpretation.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
|
|
GO:0033554
cellular response to stress
|
IEA
GO_REF:0000118 |
MARK AS OVER ANNOTATED |
Summary: Cellular response to stress is too broad for an enzyme whose direct role is peroxide reduction.
Reason: Use peroxide detoxification and oxidative-stress annotations rather than this generic stress-response process.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
|
|
GO:0042744
hydrogen peroxide catabolic process
|
IEA
GO_REF:0000118 |
ACCEPT |
Summary: Hydrogen peroxide catabolic process is directly supported by the peroxidase reaction described for TsaA. H2O2 is the best-supported, directly assayed substrate for the KT2440 protein per the falcon report.
Reason: The UniProt function states that the enzyme reduces hydrogen peroxide to water, and KT2440 experiments directly assayed PP_1084/PpPrx against H2O2.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
The best-supported primary substrate in KT2440 experiments is **H2O2**, with broader substrate scope (e.g., organic hydroperoxides, peroxynitrite) supported by strong family-level evidence for typical 2-Cys peroxiredoxins
|
|
GO:0045454
cell redox homeostasis
|
IEA
GO_REF:0000118 |
KEEP AS NON CORE |
Summary: Cell redox homeostasis is consistent with peroxiredoxin function but broader than direct peroxide detoxification. The falcon report notes the thioredoxin system primarily guides the redox-dependent structural/functional switching of PP_1084.
Reason: Retain as a supported non-core process because peroxide reduction contributes to redox balance.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
Exposure to **H2O2** drives structural changes and a corresponding functional switch, and the thioredoxin system is described as a primary guide of this switching behavior
|
|
GO:0051920
peroxiredoxin activity
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: Peroxiredoxin activity is a specific and supported molecular function for this AhpC/Prx1-family protein. The falcon report confirms the directly studied KT2440 protein PP_1084 (PpPrx) is a 21 kDa AhpC/Tsa-family typical 2-Cys peroxiredoxin, matching the UniProt subfamily assignment.
Reason: UniProt identifies the protein as a thioredoxin peroxidase/peroxiredoxin family member that reduces peroxides, and the KT2440-specific study confirms typical 2-Cys peroxiredoxin classification.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Belongs to the peroxiredoxin family
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
identifying it as a **21 kDa AhpC/Tsa family peroxiredoxin** (typical 2-Cys), which aligns with the UniProt description and subfamily assignment
|
|
GO:0098869
cellular oxidant detoxification
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: Cellular oxidant detoxification captures the biological process consequence of peroxide reduction. The falcon report documents that in KT2440 the protein was found among disulfide-bonded proteins enriched after oxidative treatments and detoxifies intracellular peroxides.
Reason: The protein detoxifies hydrogen peroxide and organic hydroperoxides, protecting cells from oxidative stress, and KT2440 evidence directly links it to intracellular peroxide detoxification.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Plays a role in cell protection against oxidative stress
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
PP1084/PpPrx was discovered among **disulfide-bonded proteins** enriched after **oxidative treatments (H2O2, gamma rays)** in KT2440, consistent with involvement in oxidative-stress response and thiol redox homeostasis
|
|
GO:0042802
identical protein binding
|
IPI
PMID:26278368 An additional cysteine in a typical 2-Cys peroxiredoxin of P... |
KEEP AS NON CORE |
Summary: Identical protein binding is supported by the IntAct self-interaction record and reflects the homo-oligomerization that is mechanistically central to TsaA/PpPrx function. The falcon report and PMID:26278368 show PP_1084/PpPrx self-associates into high-molecular-weight (HMW, chaperone-active) and low-molecular-weight (LMW, peroxidase-active) forms, so self-association underpins the redox-dependent peroxidase/chaperone switch.
Reason: Retain as non-core self-association evidence; while peripheral to the catalytic chemistry itself, the homo-oligomerization it captures drives the functional switching between peroxidase and chaperone states.
Supporting Evidence:
file:PSEPK/PP_1084/PP_1084-uniprot.txt
Q88NW9; Q88NW9: tsaA; NbExp=4
PMID:26278368
PpPrx and PaPrx can alternatively function as a peroxidase and chaperone
file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
PP_1084/PpPrx self-associates into high-molecular-weight (HMW) complexes and lower-molecular-weight (LMW) species
|
|
GO:0051082
unfolded protein binding
|
IDA
PMID:26278368 An additional cysteine in a typical 2-Cys peroxiredoxin of P... |
NEW |
Summary: PP_1084/PpPrx has experimentally demonstrated molecular chaperone (holdase) activity. In its high-molecular-weight oligomeric state it suppresses thermal aggregation of model substrate proteins, and this chaperone state interconverts with the low-molecular-weight peroxidase-active form under redox control. This dual peroxidase/chaperone function is well documented for this protein but is not captured by any of the existing GOA annotations, so it is proposed as a NEW molecular-function annotation.
Reason: An et al. (PMID:26278368, and PMID:21104173) directly show PpPrx (PP_1084) functions as a molecular chaperone in addition to its peroxidase activity, with chaperone activity associated with the HMW oligomeric form. Unfolded protein binding (GO:0051082) is the appropriate molecular-function term for this holdase activity.
Supporting Evidence:
PMID:26278368
PpPrx and PaPrx can alternatively function as a peroxidase and chaperone
PMID:26278368
PpPrx predominates with a high molecular weight (HMW) complex and
|
Q: Under which physiological oxidative-stress conditions in KT2440 does TsaA/PpPrx shift between the HMW chaperone-active and LMW peroxidase-active oligomeric states, and what is the in vivo balance of these two functions?
Suggested experts: Bacterial oxidative stress experts
Q: Does KT2440 TsaA reduce organic hydroperoxides and peroxynitrite in addition to H2O2, as predicted from AhpC/Prx1 subfamily membership?
Suggested experts: Peroxiredoxin enzymology experts
Experiment: Measure peroxide-reduction kinetics (H2O2 and organic hydroperoxides) and oligomeric state changes for purified TsaA under peroxide and thioredoxin/thioredoxin-reductase conditions, using size-exclusion chromatography to resolve HMW versus LMW species.
Type: redox enzyme assay
Experiment: Assess molecular chaperone (holdase) activity of purified TsaA by thermal- and chemical-aggregation suppression assays with model substrates, correlating activity with oligomeric state and redox conditions.
Type: chaperone aggregation-suppression assay
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
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Pseudomonas putida KT2440 locus PP_1084 encodes a cytosolic AhpC/Prx1-family (typical 2-Cys) peroxiredoxin, experimentally characterized as a thioredoxin-dependent peroxidase that can also act as a stress-responsive molecular chaperone via oligomerization-dependent functional switching. The best-supported primary substrate in KT2440 experiments is H2O2, with broader substrate scope (e.g., organic hydroperoxides, peroxynitrite) supported by strong family-level evidence for typical 2-Cys peroxiredoxins. In KT2440, peroxide exposure promotes conversion of high-molecular-weight chaperone assemblies into low-molecular-weight forms with higher peroxidase activity, consistent with a redox-controlled homeostatic role in intracellular peroxide detoxification. (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11)
The UniProt target (Q88NW9) is annotated as Thioredoxin peroxidase, gene name tsaA, ordered locus PP_1084, in P. putida KT2440, belonging to the peroxiredoxin family (AhpC/Prx1 subfamily).
A KT2440-focused biochemical study directly investigated PP1084 (noted as “PP1084 of P. putida KT2440”), identifying it as a 21 kDa AhpC/Tsa family peroxiredoxin (typical 2-Cys), which aligns with the UniProt description and subfamily assignment. (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8)
Within the retrieved literature, PP1084 is consistently discussed as an AhpC/Tsa-family peroxiredoxin from P. putida KT2440, and no conflicting “tsaA” assignments (to unrelated proteins or different organisms) were encountered in the evidence base assembled here. (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 4-6)
Peroxiredoxins (Prxs) are widespread thiol-dependent peroxidases that reduce peroxides using redox-active cysteines, protecting cells from oxidative stress and—depending on context—participating in redox regulation. In bacteria, AhpC-type Prxs are major peroxide-detoxifying enzymes and are often called thioredoxin-dependent peroxidases. (an2011functionalswitchingof pages 1-2, thapa2023theroleof pages 1-2)
The AhpC/Prx1 (typical 2-Cys) group is defined by a canonical two-cysteine catalytic cycle in which a peroxidatic cysteine (CP) forms a sulfenic acid intermediate and then resolves via a resolving cysteine (CR) to form a (typically intersubunit) disulfide bond. (sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 8-10, thapa2023theroleof pages 2-4)
Family-level (authoritative) synthesis describes the typical 2-Cys Prx mechanism as:
1) CP-SH reacts with peroxide (e.g., H2O2) → CP-SOH (sulfenic acid)
2) CP-SOH + CR-SH (often from the partner subunit) → intersubunit disulfide
3) The disulfide is reduced back to active thiols primarily by thioredoxin (Trx), which is regenerated by thioredoxin reductase (TrxR) using NADPH.
This cycle is the central biochemical meaning of “thioredoxin peroxidase.” (sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 8-10, thapa2023theroleof pages 2-4)
A KT2440 study (An et al., 2011; DOI https://doi.org/10.1007/s12192-010-0243-5; May 2011) characterized PP1084 (renamed PpPrx) as a typical 2-Cys peroxiredoxin that is Trx-dependent and shows dual functionality:
- Peroxidase activity detectable in a thioredoxin-coupled assay, with activity enriched in low-molecular-weight (LMW) forms. (an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11)
- Chaperone activity enriched in high-molecular-weight (HMW) oligomeric complexes, demonstrated by suppression of thermal aggregation of model substrates (e.g., malate dehydrogenase), consistent with a “holdase”-type stress chaperone function. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8)
Direct evidence in KT2440: PP1084/PpPrx was assayed against H2O2, and H2O2 exposure is a central perturbation driving its structural/functional switching. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 10-11, an2011functionalswitchingof pages 2-4)
Family-supported substrate scope: Typical 2-Cys peroxiredoxins (AhpC/Prx1-like) reduce H2O2 and also organic hydroperoxides (ROOH, including alkyl/lipid hydroperoxides); many also reduce peroxynitrite. This broader specificity is well supported in 2023 literature synthesizing peroxiredoxin chemistry and substrate range (even when the example protein is eukaryotic, the mechanistic and chemical principles apply to typical 2-Cys Prxs). (sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 10-11, thapa2023theroleof pages 1-2, thapa2023theroleof pages 2-4)
Important limitation: In the retrieved KT2440 primary study excerpts, direct measurements of PP1084 activity toward organic hydroperoxides were not observed; thus, organic-hydroperoxide activity is currently best treated as a high-confidence inference from subfamily membership, rather than a KT2440-specific experimental fact in the evidence assembled here. (sadowskabartosz2023peroxiredoxin2an pages 2-4, thapa2023theroleof pages 1-2)
For PP1084/PpPrx, sequence analysis reported two highly conserved “VCP” tripeptides, linked by the authors to catalytic function in typical 2-Cys peroxiredoxins, supporting the peroxiredoxin assignment and cysteine-based catalysis. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8)
Important limitation: The retrieved excerpts did not provide explicit residue numbers (e.g., “Cys47/Cys170”) for KT2440 PP1084; mechanistic residue positions are therefore presented as typical-family features rather than KT2440-specific numbering. (guevaraflores2024aphysiologicalapproach pages 1-2)
PP1084/PpPrx was discovered among disulfide-bonded proteins enriched after oxidative treatments (H2O2, gamma rays) in KT2440, consistent with involvement in oxidative-stress response and thiol redox homeostasis. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 1-2)
A key KT2440-specific mechanistic insight is that PP1084 undergoes stress-dependent transitions between:
- HMW complexes with strong chaperone activity, and
- LMW species with increased peroxidase activity.
Exposure to H2O2 drives structural changes and a corresponding functional switch, and the thioredoxin system is described as a primary guide of this switching behavior. This supports a model in which PP1084 contributes both to (i) detoxification of peroxides and (ii) protection of other proteins from oxidative/heat stress via chaperone-like oligomeric assemblies. (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11)
PSORTb-based prediction placed PP1084/PpPrx in the cytoplasm, aligning with expected localization for a thioredoxin-coupled peroxide detox enzyme operating on intracellular peroxides and protein thiol redox balance. (an2011functionalswitchingof pages 4-6)
Because KT2440-specific publications in 2023–2024 mentioning PP_1084/tsaA directly were not retrieved here, “recent developments” are summarized as state-of-the-art insights in typical 2-Cys peroxiredoxin biology that sharpen functional interpretation of bacterial AhpC/Prx1 enzymes.
A 2023 synthesis reports that typical 2-Cys peroxiredoxins show high reactivity with H2O2, with second-order rate constants spanning approximately 10^5–10^8 M−1 s−1 (method-dependent), and describes competition between productive disulfide formation versus hyperoxidation using parameters around kd ~2 s−1 and kh ~1×10^4 M−1 s−1. It also reports thioredoxin-based recycling parameters on the order of ~2.1×10^5 M−1 s−1 with Km ~2–2.7 µM for thioredoxin in a typical 2-Cys context. These quantitative ranges provide modern benchmarks for interpreting the efficiency and redox-control logic of bacterial AhpC/Prx1 enzymes such as KT2440 TsaA. (sadowskabartosz2023peroxiredoxin2an pages 8-10)
A 2024 source highlights that many Prxs are sensitive to overoxidation under micromolar H2O2 and discusses motifs (e.g., “GGLG” and “YP”) associated with hyperoxidation sensitivity, while noting “robust” bacterial Prxs (e.g., E. coli, Salmonella) that lack those motifs and instead possess alternative motifs associated with resistance. It also frames how modest catalytic efficiencies (reported as kcat/Km ~10^4–10^5 M−1 s−1 in that source) can still yield effective peroxide control if intracellular concentrations are high (cited typical Prx concentrations around ~15–60 µM). This is relevant to functional annotation of KT2440 TsaA because it emphasizes that cellular abundance and recycling can be as important as intrinsic catalytic parameters. (guevaraflores2024aphysiologicalapproach pages 1-2)
A 2024 bioremediation-focused study in Paraburkholderia xenovorans reports that aromatic compound catabolism (hydroxyphenylacetates) induces oxidative stress and upregulates multiple peroxide detox enzymes including Ahp components and peroxiredoxins (e.g., AhpC2/AhpF/AhpD3, Prx1/Prx2, catalase). This supports a current applied research theme: successful aromatic degradation in soil-relevant bacteria requires active peroxide control programs, of which AhpC/Prx systems are prominent members. While not KT2440-specific, it supports the rationale that KT2440 peroxiredoxins likely contribute to its frequent use as an oxidative-stress-tolerant chassis for xenobiotic metabolism. (rodriguezcastro2024thelongchainflavodoxin pages 1-2, rodriguezcastro2024thelongchainflavodoxin pages 13-15)
Within the retrieved corpus, no direct industrial or field deployment specifically manipulating KT2440 PP_1084/tsaA was found. The best KT2440-specific contribution is mechanistic: PP1084 responds to peroxide stress and can act as a peroxide-reductase and chaperone—properties that are plausibly beneficial for industrial robustness, but this is not demonstrated here as an applied implementation. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 1-2)
Rodríguez-Castro et al. (Apr 2024; DOI https://doi.org/10.1186/s40659-024-00491-4) tested engineered redox protection in soil microcosms, showing improved biodegradation of an aromatic pollutant (4-HPA) by a strain overexpressing a protective flavodoxin. The study concurrently reports that antioxidant/peroxide-control systems including Ahp/peroxiredoxin-related enzymes are upregulated during aromatic catabolism. The microcosm result constitutes a real-world implementation relevant to peroxiredoxin-mediated oxidative defense: oxidative-stress detox capacity (including Ahp/Prx systems) is a key determinant of biodegradation performance and strain fitness in soil-like environments. (rodriguezcastro2024thelongchainflavodoxin pages 10-11, rodriguezcastro2024thelongchainflavodoxin pages 1-2)
Recent authoritative syntheses emphasize the following themes relevant to bacterial AhpC/Prx1 (and thus to KT2440 TsaA):
1) Peroxiredoxins are among the earliest and most sensitive peroxide defenses, reacting rapidly with H2O2 via a specialized cysteine chemistry (peroxidatic cysteine) and being recycled mainly by thioredoxin systems. (sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 8-10)
2) Oligomerization can be functional, linking redox state to peroxidase vs chaperone behavior; this is not purely an in vitro curiosity but a plausible stress-adaptation strategy. (thapa2023theroleof pages 1-2, an2011functionalswitchingof pages 10-11)
3) Hyperoxidation and robustness are important design/selection principles, especially in microbes experiencing recurring oxidative stress; sequence motifs and recycling capacity shape functional regimes. (guevaraflores2024aphysiologicalapproach pages 1-2, sadowskabartosz2023peroxiredoxin2an pages 2-4)
Key quantitative values from recent (2023–2024) sources relevant to interpreting KT2440 TsaA-type enzymes include:
- Typical 2-Cys Prx reaction with H2O2: ~10^5–10^8 M−1 s−1 (range across methods/contexts). (sadowskabartosz2023peroxiredoxin2an pages 8-10)
- Competition of disulfide formation vs hyperoxidation (example parameterization): kd ~2 s−1, kh ~1×10^4 M−1 s−1. (sadowskabartosz2023peroxiredoxin2an pages 8-10)
- Thioredoxin reduction parameters (example typical 2-Cys context): ~2.1×10^5 M−1 s−1, Km ~2–2.7 µM. (sadowskabartosz2023peroxiredoxin2an pages 8-10)
- Typical intracellular Prx concentrations cited: ~15–60 µM, supporting the idea that abundance can compensate for moderate kcat/Km in vivo. (guevaraflores2024aphysiologicalapproach pages 1-2)
KT2440-specific quantitative limitation: The KT2440 PP1084 study excerpts available here provide qualitative/relative activity statements (e.g., lower peroxidase activity relative to a yeast Prx control, higher chaperone activity) but do not provide a full kinetic parameter table in the extracted evidence; therefore, the numeric “statistics” above are best treated as current family-level reference values, not direct measurements of Q88NW9. (an2011functionalswitchingof pages 10-11, sadowskabartosz2023peroxiredoxin2an pages 8-10)
The following table links each major functional-annotation claim to its strongest supporting sources, with publication metadata.
| Item | Key finding | Organism context (KT2440 vs general) | Best supporting citation IDs | Publication info (authors, year, title, DOI/URL, month/year) |
|---|---|---|---|---|
| Identity | PP_1084 from Pseudomonas putida KT2440 is a 21 kDa AhpC/Tsa-family peroxiredoxin (typical 2-Cys Prx); this matches the UniProt Q88NW9 annotation as TsaA/thioredoxin peroxidase rather than an unrelated protein family. | KT2440-specific | (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, Cell Stress and Chaperones, DOI: https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Primary function | PP_1084/PpPrx is a thioredoxin-dependent peroxide-detoxifying enzyme with dual behavior: peroxidase activity plus stress-associated molecular chaperone activity. | KT2440-specific | (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Mechanism | As an AhpC/Prx1 typical 2-Cys peroxiredoxin, the catalytic cycle is inferred to use a peroxidatic cysteine oxidized to sulfenic acid, then an intersubunit disulfide with a resolving cysteine, followed by thioredoxin-dependent reduction. | General AhpC/Prx1 mechanism, applied to PP_1084 family assignment | (sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 8-10, guevaraflores2024aphysiologicalapproach pages 1-2, thapa2023theroleof pages 2-4) | Sadowska-Bartosz I & Bartosz G, 2023, Peroxiredoxin 2: An Important Element of the Antioxidant Defense of the Erythrocyte, https://doi.org/10.3390/antiox12051012, Apr 2023; Guevara-Flores A et al., 2024, A Physiological Approach to Explore How Thioredoxin–Glutathione Reductase (TGR) and Peroxiredoxin (Prx) Eliminate H2O2 in Cysticerci of Taenia, https://doi.org/10.3390/antiox13040444, Apr 2024; Thapa P et al., 2023, The Role of Peroxiredoxins in Cancer Development, https://doi.org/10.3390/biology12050666, Apr 2023 |
| Catalytic residue clues | Sequence analysis of PpPrx found two highly conserved VCP tripeptides associated with catalytic cysteines, supporting classification as a typical 2-Cys peroxiredoxin, although exact PP_1084 residue numbers were not given in the retrieved excerpts. | KT2440-specific sequence feature | (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Substrates | Direct KT2440 evidence supports activity toward H2O2; by subfamily inference, AhpC/Prx1 enzymes also reduce organic hydroperoxides and can act on peroxynitrite. | H2O2: KT2440-specific; broader substrate range: general AhpC/Prx1 | (an2011functionalswitchingof pages 4-6, sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 10-11, thapa2023theroleof pages 1-2, thapa2023theroleof pages 2-4) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011; Sadowska-Bartosz I & Bartosz G, 2023, Peroxiredoxin 2..., https://doi.org/10.3390/antiox12051012, Apr 2023; Thapa P et al., 2023, The Role of Peroxiredoxins in Cancer Development, https://doi.org/10.3390/biology12050666, Apr 2023 |
| Reductant / partner system | Peroxidase activity for PP_1084 was measured with a yeast thioredoxin system, and the authors conclude structural/functional switching is primarily guided by the thioredoxin system; this fits canonical Trx/TrxR/NADPH recycling of AhpC/Prx1 enzymes. | KT2440-specific experimental dependence plus general family mechanism | (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11, sadowskabartosz2023peroxiredoxin2an pages 2-4, sadowskabartosz2023peroxiredoxin2an pages 8-10) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011; Sadowska-Bartosz I & Bartosz G, 2023, Peroxiredoxin 2..., https://doi.org/10.3390/antiox12051012, Apr 2023 |
| Oligomerization | PP_1084/PpPrx self-associates into high-molecular-weight (HMW) complexes and lower-molecular-weight (LMW) species; typical 2-Cys Prxs generally exist as dimers and larger toroid/decamer-like assemblies. | KT2440-specific plus general family context | (an2011functionalswitchingof pages 1-2, an2011functionalswitchingof pages 6-8, thapa2023theroleof pages 1-2) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011; Thapa P et al., 2023, The Role of Peroxiredoxins in Cancer Development, https://doi.org/10.3390/biology12050666, Apr 2023 |
| Chaperone role | In KT2440, HMW PP_1084 complexes have strong molecular chaperone activity, suppressing thermal aggregation of model substrates; oxidative conditions shift the balance toward LMW forms with greater peroxidase activity. | KT2440-specific | (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11, an2011functionalswitchingof pages 1-2) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Localization | PSORTb prediction places PP_1084/PpPrx in the cytoplasm, consistent with a role in intracellular peroxide detoxification and thioredoxin-linked redox homeostasis. | KT2440-specific prediction | (an2011functionalswitchingof pages 4-6) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Biological process / pathway | The protein functions in oxidative-stress defense/redox homeostasis, especially detoxification of intracellular peroxides generated during stress; in KT2440 it was isolated among disulfide-bonded proteins after H2O2 or gamma-ray exposure. | KT2440-specific, with family-level redox-homeostasis context | (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 2-4, an2011functionalswitchingof pages 1-2) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Activity level nuance | The recombinant KT2440 protein showed detectable but comparatively low H2O2 peroxidase activity versus a yeast thioredoxin peroxidase control, while exhibiting comparatively stronger chaperone activity. | KT2440-specific | (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 10-11) | An BC et al., 2011, Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress, https://doi.org/10.1007/s12192-010-0243-5, May 2011 |
| Recent kinetics/statistics | Recent reviews report typical 2-Cys Prx reaction rates with H2O2 in the ~10^5–10^8 M−1 s−1 range; competing condensation vs hyperoxidation parameters around kd ~2 s−1 and kh ~1×10^4 M−1 s−1; thioredoxin reduction second-order rate ~2.1×10^5 M−1 s−1 with Km ~2–2.7 µM; intracellular concentrations can be ~15–60 µM. These are family-level values, not KT2440-specific measurements. | General current understanding (2023–2024) | (sadowskabartosz2023peroxiredoxin2an pages 8-10, guevaraflores2024aphysiologicalapproach pages 1-2) | Sadowska-Bartosz I & Bartosz G, 2023, Peroxiredoxin 2..., https://doi.org/10.3390/antiox12051012, Apr 2023; Guevara-Flores A et al., 2024, A Physiological Approach to Explore How Thioredoxin–Glutathione Reductase (TGR) and Peroxiredoxin (Prx) Eliminate H2O2 in Cysticerci of Taenia, https://doi.org/10.3390/antiox13040444, Apr 2024 |
| Hyperoxidation / robustness context | Recent literature distinguishes hyperoxidation-sensitive versus robust typical 2-Cys Prxs by conserved motifs; bacterial AhpC-like enzymes are often more resistant to hyperoxidation than many eukaryotic homologs, supporting durable antioxidant function during repeated oxidative challenge. | General bacterial AhpC/Prx1 context | (sadowskabartosz2023peroxiredoxin2an pages 2-4, guevaraflores2024aphysiologicalapproach pages 1-2) | Sadowska-Bartosz I & Bartosz G, 2023, Peroxiredoxin 2..., https://doi.org/10.3390/antiox12051012, Apr 2023; Guevara-Flores A et al., 2024, A Physiological Approach to Explore How Thioredoxin–Glutathione Reductase (TGR) and Peroxiredoxin (Prx) Eliminate H2O2 in Cysticerci of Taenia, https://doi.org/10.3390/antiox13040444, Apr 2024 |
| Applications / implementations | No direct applied implementation of PP_1084 itself was found in the retrieved KT2440 literature. However, 2024 bioremediation work in another soil bacterium shows that oxidative-stress programs involving Ahp/peroxiredoxin enzymes are upregulated during aromatic-compound degradation and are relevant to strain robustness and soil-microcosm biodegradation performance; thus PP_1084 likely contributes to the oxidative-stress tolerance valued in P. putida as a biotechnological chassis. | KT2440 evidence indirect; application evidence from related bacteria/general Pseudomonas biotechnology context | (rodriguezcastro2024thelongchainflavodoxin pages 13-15, rodriguezcastro2024thelongchainflavodoxin pages 10-11, rodriguezcastro2024thelongchainflavodoxin pages 1-2, nies2022engineeringpseudomonasfora pages 171-174, nies2022engineeringpseudomonasfor pages 171-174) | Rodríguez-Castro L et al., 2024, The long-chain flavodoxin FldX1 improves the biodegradation of 4-hydroxyphenylacetate and 3-hydroxyphenylacetate and counteracts the oxidative stress associated to aromatic catabolism in Paraburkholderia xenovorans, https://doi.org/10.1186/s40659-024-00491-4, Apr 2024; Nies SC, 2022, Engineering Pseudomonas for the production of reduced compounds, journal/DOI not fully resolved in retrieved metadata, 2022 |
Table: This table summarizes the main functional annotation evidence for Pseudomonas putida KT2440 tsaA/PP_1084 (UniProt Q88NW9), distinguishing direct KT2440 data from broader AhpC/Prx1 family inference. It is useful for tracing each annotation claim to specific supporting citations and recent mechanistic context.
Gene/protein: tsaA / PP_1084 (UniProt Q88NW9) — Thioredoxin peroxidase / typical 2-Cys peroxiredoxin (AhpC/Prx1 family)
Molecular function: Thioredoxin-dependent peroxidase reducing H2O2 (direct evidence) and likely organic hydroperoxides (subfamily inference); can form HMW oligomers with chaperone-like activity and LMW peroxidase-active forms; redox-dependent oligomerization mediates functional switching under oxidative stress. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 6-8, an2011functionalswitchingof pages 10-11, sadowskabartosz2023peroxiredoxin2an pages 2-4, thapa2023theroleof pages 1-2)
Cellular component: Cytosol (prediction). (an2011functionalswitchingof pages 4-6)
Biological process: Oxidative stress response / peroxide detoxification; protein protection under oxidative/heat stress via chaperone-like assemblies. (an2011functionalswitchingof pages 4-6, an2011functionalswitchingof pages 1-2)
References
(an2011functionalswitchingof pages 1-2): Byung Chull An, Seung Sik Lee, Eun Mi Lee, Jae Taek Lee, Seung Gon Wi, Hyun Suk Jung, Woojun Park, Sang Yeol Lee, and Byung Yeoup Chung. Functional switching of a novel prokaryotic 2-cys peroxiredoxin (ppprx) under oxidative stress. Cell Stress and Chaperones, 16:317-328, May 2011. URL: https://doi.org/10.1007/s12192-010-0243-5, doi:10.1007/s12192-010-0243-5. This article has 23 citations and is from a peer-reviewed journal.
(an2011functionalswitchingof pages 4-6): Byung Chull An, Seung Sik Lee, Eun Mi Lee, Jae Taek Lee, Seung Gon Wi, Hyun Suk Jung, Woojun Park, Sang Yeol Lee, and Byung Yeoup Chung. Functional switching of a novel prokaryotic 2-cys peroxiredoxin (ppprx) under oxidative stress. Cell Stress and Chaperones, 16:317-328, May 2011. URL: https://doi.org/10.1007/s12192-010-0243-5, doi:10.1007/s12192-010-0243-5. This article has 23 citations and is from a peer-reviewed journal.
(an2011functionalswitchingof pages 6-8): Byung Chull An, Seung Sik Lee, Eun Mi Lee, Jae Taek Lee, Seung Gon Wi, Hyun Suk Jung, Woojun Park, Sang Yeol Lee, and Byung Yeoup Chung. Functional switching of a novel prokaryotic 2-cys peroxiredoxin (ppprx) under oxidative stress. Cell Stress and Chaperones, 16:317-328, May 2011. URL: https://doi.org/10.1007/s12192-010-0243-5, doi:10.1007/s12192-010-0243-5. This article has 23 citations and is from a peer-reviewed journal.
(an2011functionalswitchingof pages 10-11): Byung Chull An, Seung Sik Lee, Eun Mi Lee, Jae Taek Lee, Seung Gon Wi, Hyun Suk Jung, Woojun Park, Sang Yeol Lee, and Byung Yeoup Chung. Functional switching of a novel prokaryotic 2-cys peroxiredoxin (ppprx) under oxidative stress. Cell Stress and Chaperones, 16:317-328, May 2011. URL: https://doi.org/10.1007/s12192-010-0243-5, doi:10.1007/s12192-010-0243-5. This article has 23 citations and is from a peer-reviewed journal.
(thapa2023theroleof pages 1-2): Pratik Thapa, Hong Jiang, Na Ding, Yanning Hao, Aziza Alshahrani, and Qiou Wei. The role of peroxiredoxins in cancer development. Biology, 12:666, Apr 2023. URL: https://doi.org/10.3390/biology12050666, doi:10.3390/biology12050666. This article has 26 citations.
(sadowskabartosz2023peroxiredoxin2an pages 2-4): Izabela Sadowska-Bartosz and Grzegorz Bartosz. Peroxiredoxin 2: an important element of the antioxidant defense of the erythrocyte. Antioxidants, 12:1012, Apr 2023. URL: https://doi.org/10.3390/antiox12051012, doi:10.3390/antiox12051012. This article has 48 citations.
(sadowskabartosz2023peroxiredoxin2an pages 8-10): Izabela Sadowska-Bartosz and Grzegorz Bartosz. Peroxiredoxin 2: an important element of the antioxidant defense of the erythrocyte. Antioxidants, 12:1012, Apr 2023. URL: https://doi.org/10.3390/antiox12051012, doi:10.3390/antiox12051012. This article has 48 citations.
(thapa2023theroleof pages 2-4): Pratik Thapa, Hong Jiang, Na Ding, Yanning Hao, Aziza Alshahrani, and Qiou Wei. The role of peroxiredoxins in cancer development. Biology, 12:666, Apr 2023. URL: https://doi.org/10.3390/biology12050666, doi:10.3390/biology12050666. This article has 26 citations.
(an2011functionalswitchingof pages 2-4): Byung Chull An, Seung Sik Lee, Eun Mi Lee, Jae Taek Lee, Seung Gon Wi, Hyun Suk Jung, Woojun Park, Sang Yeol Lee, and Byung Yeoup Chung. Functional switching of a novel prokaryotic 2-cys peroxiredoxin (ppprx) under oxidative stress. Cell Stress and Chaperones, 16:317-328, May 2011. URL: https://doi.org/10.1007/s12192-010-0243-5, doi:10.1007/s12192-010-0243-5. This article has 23 citations and is from a peer-reviewed journal.
(sadowskabartosz2023peroxiredoxin2an pages 10-11): Izabela Sadowska-Bartosz and Grzegorz Bartosz. Peroxiredoxin 2: an important element of the antioxidant defense of the erythrocyte. Antioxidants, 12:1012, Apr 2023. URL: https://doi.org/10.3390/antiox12051012, doi:10.3390/antiox12051012. This article has 48 citations.
(guevaraflores2024aphysiologicalapproach pages 1-2): Alberto Guevara-Flores, Gabriela Nava-Balderas, José de Jesús Martínez-González, César Vásquez-Lima, Juan Luis Rendón, and Irene Patricia del Arenal Mena. A physiological approach to explore how thioredoxin–glutathione reductase (tgr) and peroxiredoxin (prx) eliminate h2o2 in cysticerci of taenia. Antioxidants, 13:444, Apr 2024. URL: https://doi.org/10.3390/antiox13040444, doi:10.3390/antiox13040444. This article has 5 citations.
(rodriguezcastro2024thelongchainflavodoxin pages 1-2): Laura Rodríguez-Castro, Roberto E. Durán, Valentina Méndez, Flavia Dorochesi, Daniela Zühlke, Katharina Riedel, and Michael Seeger. The long-chain flavodoxin fldx1 improves the biodegradation of 4-hydroxyphenylacetate and 3-hydroxyphenylacetate and counteracts the oxidative stress associated to aromatic catabolism in paraburkholderia xenovorans. Biological Research, Apr 2024. URL: https://doi.org/10.1186/s40659-024-00491-4, doi:10.1186/s40659-024-00491-4. This article has 10 citations and is from a peer-reviewed journal.
(rodriguezcastro2024thelongchainflavodoxin pages 13-15): Laura Rodríguez-Castro, Roberto E. Durán, Valentina Méndez, Flavia Dorochesi, Daniela Zühlke, Katharina Riedel, and Michael Seeger. The long-chain flavodoxin fldx1 improves the biodegradation of 4-hydroxyphenylacetate and 3-hydroxyphenylacetate and counteracts the oxidative stress associated to aromatic catabolism in paraburkholderia xenovorans. Biological Research, Apr 2024. URL: https://doi.org/10.1186/s40659-024-00491-4, doi:10.1186/s40659-024-00491-4. This article has 10 citations and is from a peer-reviewed journal.
(rodriguezcastro2024thelongchainflavodoxin pages 10-11): Laura Rodríguez-Castro, Roberto E. Durán, Valentina Méndez, Flavia Dorochesi, Daniela Zühlke, Katharina Riedel, and Michael Seeger. The long-chain flavodoxin fldx1 improves the biodegradation of 4-hydroxyphenylacetate and 3-hydroxyphenylacetate and counteracts the oxidative stress associated to aromatic catabolism in paraburkholderia xenovorans. Biological Research, Apr 2024. URL: https://doi.org/10.1186/s40659-024-00491-4, doi:10.1186/s40659-024-00491-4. This article has 10 citations and is from a peer-reviewed journal.
(nies2022engineeringpseudomonasfora pages 171-174): SC Nies. Engineering pseudomonas for the production of reduced compounds. Unknown journal, 2022.
(nies2022engineeringpseudomonasfor pages 171-174): SC Nies. Engineering pseudomonas for the production of reduced compounds. Unknown journal, 2022.
id: Q88NW9
gene_symbol: tsaA
product_type: PROTEIN
status: DRAFT
taxon:
id: NCBITaxon:160488
label: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
description: >-
tsaA (locus PP_1084) encodes a cytoplasmic AhpC/Prx1-family (typical 2-Cys) thioredoxin peroxidase/peroxiredoxin
(PpPrx). Its core role is thioredoxin-dependent reduction and detoxification of hydrogen peroxide (and, by
subfamily inference, organic hydroperoxides), contributing to cellular oxidant detoxification and redox stress
protection in KT2440. The directly studied KT2440 protein additionally displays a redox-dependent molecular
chaperone (holdase) activity; it self-associates into high-molecular-weight oligomers that suppress protein
aggregation, and oxidative conditions drive a structural switch toward low-molecular-weight peroxidase-active
forms, constituting a peroxidase/chaperone functional switch (PMID:21104173, PMID:26278368).
existing_annotations:
- term:
id: GO:0004601
label: peroxidase activity
evidence_type: IEA
original_reference_id: GO_REF:0000117
review:
summary: Peroxidase activity is correct for this thiol-specific peroxidase, although the peroxiredoxin/thioredoxin peroxidase terms are more informative.
action: ACCEPT
reason: UniProt describes reduction of hydrogen peroxide and organic hydroperoxides, supporting peroxidase activity.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- term:
id: GO:0005737
label: cytoplasm
evidence_type: IEA
original_reference_id: GO_REF:0000117
review:
summary: Cytoplasm is directly supported by the UniProt subcellular-location statement and corroborated by a PSORTb cytoplasmic prediction for KT2440 PP_1084 in the falcon report.
action: ACCEPT
reason: The protein is annotated as cytoplasmic and has no evidence for another compartment; a PSORTb prediction independently places PP_1084/PpPrx in the cytoplasm.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm'
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: PSORTb-based prediction placed PP1084/PpPrx in the **cytoplasm**, aligning with expected localization for a thioredoxin-coupled peroxide detox enzyme operating on intracellular peroxides and protein thiol redox balance
- term:
id: GO:0005829
label: cytosol
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: Cytosol is compatible with the cytoplasmic location, but it is not the core function. A PSORTb cytoplasmic prediction for KT2440 PP_1084 in the falcon report is consistent with this assignment.
action: KEEP_AS_NON_CORE
reason: Retain as a non-core location annotation in the bacterial cytoplasm/cytosol context.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm'
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: PSORTb-based prediction placed PP1084/PpPrx in the **cytoplasm**, aligning with expected localization for a thioredoxin-coupled peroxide detox enzyme operating on intracellular peroxides and protein thiol redox balance
- term:
id: GO:0006979
label: response to oxidative stress
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: Response to oxidative stress is supported but broad relative to direct peroxide detoxification. The falcon report notes the protein was enriched after oxidative treatments (H2O2, gamma rays) in KT2440.
action: KEEP_AS_NON_CORE
reason: The protein protects against oxidative stress through peroxidase activity; the direct detoxification process terms are more specific.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: PP1084/PpPrx was discovered among **disulfide-bonded proteins** enriched after **oxidative treatments (H2O2, gamma rays)** in KT2440, consistent with involvement in oxidative-stress response and thiol redox homeostasis
- term:
id: GO:0008379
label: thioredoxin peroxidase activity
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: Thioredoxin peroxidase activity is the specific catalytic role of TsaA. The falcon report confirms that the directly characterized KT2440 protein (PpPrx) is a thioredoxin-dependent peroxidase assayed with a thioredoxin-coupled system, consistent with this term.
action: ACCEPT
reason: The UniProt entry identifies the protein as a thiol-specific/thioredoxin peroxidase that reduces peroxides, and the directly studied KT2440 protein PpPrx (PP_1084) is experimentally a thioredoxin-dependent peroxidase.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: locus **PP_1084** encodes a cytosolic **AhpC/Prx1-family (typical 2-Cys) peroxiredoxin**, experimentally characterized as a **thioredoxin-dependent peroxidase** that can also act as a **stress-responsive molecular chaperone** via oligomerization-dependent functional switching
- term:
id: GO:0016209
label: antioxidant activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Antioxidant activity is true in a broad sense but is less informative than peroxiredoxin and thioredoxin peroxidase activity.
action: MARK_AS_OVER_ANNOTATED
reason: The annotation should prioritize the direct enzymatic activity rather than a generic antioxidant-function parent.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- term:
id: GO:0016491
label: oxidoreductase activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Oxidoreductase activity is a broad parent that adds little beyond the specific peroxiredoxin/peroxidase terms.
action: MARK_AS_OVER_ANNOTATED
reason: The specific peroxide-reduction terms are available and should carry the functional interpretation.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- term:
id: GO:0033554
label: cellular response to stress
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: Cellular response to stress is too broad for an enzyme whose direct role is peroxide reduction.
action: MARK_AS_OVER_ANNOTATED
reason: Use peroxide detoxification and oxidative-stress annotations rather than this generic stress-response process.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- term:
id: GO:0042744
label: hydrogen peroxide catabolic process
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: Hydrogen peroxide catabolic process is directly supported by the peroxidase reaction described for TsaA. H2O2 is the best-supported, directly assayed substrate for the KT2440 protein per the falcon report.
action: ACCEPT
reason: The UniProt function states that the enzyme reduces hydrogen peroxide to water, and KT2440 experiments directly assayed PP_1084/PpPrx against H2O2.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: The best-supported primary substrate in KT2440 experiments is **H2O2**, with broader substrate scope (e.g., organic hydroperoxides, peroxynitrite) supported by strong family-level evidence for typical 2-Cys peroxiredoxins
- term:
id: GO:0045454
label: cell redox homeostasis
evidence_type: IEA
original_reference_id: GO_REF:0000118
review:
summary: Cell redox homeostasis is consistent with peroxiredoxin function but broader than direct peroxide detoxification. The falcon report notes the thioredoxin system primarily guides the redox-dependent structural/functional switching of PP_1084.
action: KEEP_AS_NON_CORE
reason: Retain as a supported non-core process because peroxide reduction contributes to redox balance.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: Exposure to **H2O2** drives structural changes and a corresponding functional switch, and the thioredoxin system is described as a primary guide of this switching behavior
- term:
id: GO:0051920
label: peroxiredoxin activity
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: Peroxiredoxin activity is a specific and supported molecular function for this AhpC/Prx1-family protein. The falcon report confirms the directly studied KT2440 protein PP_1084 (PpPrx) is a 21 kDa AhpC/Tsa-family typical 2-Cys peroxiredoxin, matching the UniProt subfamily assignment.
action: ACCEPT
reason: UniProt identifies the protein as a thioredoxin peroxidase/peroxiredoxin family member that reduces peroxides, and the KT2440-specific study confirms typical 2-Cys peroxiredoxin classification.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Belongs to the peroxiredoxin family
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: identifying it as a **21 kDa AhpC/Tsa family peroxiredoxin** (typical 2-Cys), which aligns with the UniProt description and subfamily assignment
- term:
id: GO:0098869
label: cellular oxidant detoxification
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: Cellular oxidant detoxification captures the biological process consequence of peroxide reduction. The falcon report documents that in KT2440 the protein was found among disulfide-bonded proteins enriched after oxidative treatments and detoxifies intracellular peroxides.
action: ACCEPT
reason: The protein detoxifies hydrogen peroxide and organic hydroperoxides, protecting cells from oxidative stress, and KT2440 evidence directly links it to intracellular peroxide detoxification.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: PP1084/PpPrx was discovered among **disulfide-bonded proteins** enriched after **oxidative treatments (H2O2, gamma rays)** in KT2440, consistent with involvement in oxidative-stress response and thiol redox homeostasis
- term:
id: GO:0042802
label: identical protein binding
evidence_type: IPI
original_reference_id: PMID:26278368
review:
summary: Identical protein binding is supported by the IntAct self-interaction record and reflects the homo-oligomerization that is mechanistically central to TsaA/PpPrx function. The falcon report and PMID:26278368 show PP_1084/PpPrx self-associates into high-molecular-weight (HMW, chaperone-active) and low-molecular-weight (LMW, peroxidase-active) forms, so self-association underpins the redox-dependent peroxidase/chaperone switch.
action: KEEP_AS_NON_CORE
reason: Retain as non-core self-association evidence; while peripheral to the catalytic chemistry itself, the homo-oligomerization it captures drives the functional switching between peroxidase and chaperone states.
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: 'Q88NW9; Q88NW9: tsaA; NbExp=4'
- reference_id: PMID:26278368
supporting_text: PpPrx and PaPrx can alternatively function as a peroxidase and chaperone
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: PP_1084/PpPrx self-associates into high-molecular-weight (HMW) complexes and lower-molecular-weight (LMW) species
- term:
id: GO:0051082
label: unfolded protein binding
evidence_type: IDA
original_reference_id: PMID:26278368
review:
summary: PP_1084/PpPrx has experimentally demonstrated molecular chaperone (holdase) activity. In its high-molecular-weight oligomeric state it suppresses thermal aggregation of model substrate proteins, and this chaperone state interconverts with the low-molecular-weight peroxidase-active form under redox control. This dual peroxidase/chaperone function is well documented for this protein but is not captured by any of the existing GOA annotations, so it is proposed as a NEW molecular-function annotation.
action: NEW
reason: An et al. (PMID:26278368, and PMID:21104173) directly show PpPrx (PP_1084) functions as a molecular chaperone in addition to its peroxidase activity, with chaperone activity associated with the HMW oligomeric form. Unfolded protein binding (GO:0051082) is the appropriate molecular-function term for this holdase activity.
supported_by:
- reference_id: PMID:26278368
supporting_text: PpPrx and PaPrx can alternatively function as a peroxidase and chaperone
- reference_id: PMID:26278368
supporting_text: PpPrx predominates with a high molecular weight (HMW) complex and
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO terms
findings:
- statement: InterPro supplied broad antioxidant/oxidoreductase and peroxiredoxin-related annotations.
- id: GO_REF:0000117
title: Electronic Gene Ontology annotations created by ARBA machine learning models
findings:
- statement: ARBA supplied peroxidase and cytoplasmic annotations that agree with the UniProt entry.
- id: GO_REF:0000118
title: TreeGrafter-generated GO annotations
findings:
- statement: TreeGrafter supplied thioredoxin peroxidase and peroxide detoxification process annotations.
- id: GO_REF:0000120
title: Combined automated GO annotation using multiple IEA methods
findings:
- statement: Combined automated methods supplied oxidative-stress process terms that require specificity review.
- id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
title: UniProtKB entry for tsaA / PP_1084
findings:
- supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- supporting_text: 'Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily'
- id: PMID:21104173
title: Functional switching of a novel prokaryotic 2-Cys peroxiredoxin (PpPrx) under oxidative stress
findings:
- statement: An et al. (2011) directly characterized PP_1084 (PpPrx) of P. putida KT2440 as a typical 2-Cys peroxiredoxin that can act as both a peroxidase and a molecular chaperone; H2O2 exposure converts high-MW chaperone complexes to low-MW peroxidase-active forms, a switch primarily guided by the thioredoxin system.
full_text_unavailable: true
- id: PMID:26278368
title: "An additional cysteine in a typical 2-Cys peroxiredoxin of Pseudomonas promotes functional switching between peroxidase and molecular chaperone."
findings:
- supporting_text: PpPrx and PaPrx can alternatively function as a peroxidase and chaperone
reference_section_type: ABSTRACT
- supporting_text: PpPrx predominates with a high molecular weight (HMW) complex and
reference_section_type: ABSTRACT
- id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
title: Falcon deep-research report on tsaA / PP_1084 (UniProt Q88NW9)
findings:
- supporting_text: locus **PP_1084** encodes a cytosolic **AhpC/Prx1-family (typical 2-Cys) peroxiredoxin**, experimentally characterized as a **thioredoxin-dependent peroxidase** that can also act as a **stress-responsive molecular chaperone** via oligomerization-dependent functional switching
- supporting_text: The best-supported primary substrate in KT2440 experiments is **H2O2**, with broader substrate scope (e.g., organic hydroperoxides, peroxynitrite) supported by strong family-level evidence for typical 2-Cys peroxiredoxins
- supporting_text: identifying it as a **21 kDa AhpC/Tsa family peroxiredoxin** (typical 2-Cys), which aligns with the UniProt description and subfamily assignment
- supporting_text: enriched in **high-molecular-weight (HMW)** oligomeric complexes, demonstrated by suppression of thermal aggregation of model substrates (e.g., malate dehydrogenase), consistent with a
- supporting_text: PSORTb-based prediction placed PP1084/PpPrx in the **cytoplasm**, aligning with expected localization for a thioredoxin-coupled peroxide detox enzyme operating on intracellular peroxides and protein thiol redox balance
- supporting_text: PP1084/PpPrx was discovered among **disulfide-bonded proteins** enriched after **oxidative treatments (H2O2, gamma rays)** in KT2440, consistent with involvement in oxidative-stress response and thiol redox homeostasis
- supporting_text: Exposure to **H2O2** drives structural changes and a corresponding functional switch, and the thioredoxin system is described as a primary guide of this switching behavior
- supporting_text: PP_1084/PpPrx self-associates into high-molecular-weight (HMW) complexes and lower-molecular-weight (LMW) species
core_functions:
- description: Cytoplasmic thioredoxin peroxidase/peroxiredoxin that reduces hydrogen peroxide and organic hydroperoxides to protect cells from oxidative stress.
molecular_function:
id: GO:0008379
label: thioredoxin peroxidase activity
directly_involved_in:
- id: GO:0042744
label: hydrogen peroxide catabolic process
- id: GO:0098869
label: cellular oxidant detoxification
locations:
- id: GO:0005737
label: cytoplasm
supported_by:
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Thiol-specific peroxidase that catalyzes the reduction of
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: Plays a role in cell protection against oxidative stress
- reference_id: file:PSEPK/PP_1084/PP_1084-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm'
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: The best-supported primary substrate in KT2440 experiments is **H2O2**, with broader substrate scope (e.g., organic hydroperoxides, peroxynitrite) supported by strong family-level evidence for typical 2-Cys peroxiredoxins
- description: Redox-dependent molecular chaperone (holdase) activity. Under oxidative/heat stress PP_1084/PpPrx self-associates into high-molecular-weight oligomeric complexes that suppress aggregation of partially unfolded proteins; this chaperone state interconverts with the low-molecular-weight peroxidase-active form, constituting a redox-controlled peroxidase/chaperone functional switch.
molecular_function:
id: GO:0051082
label: unfolded protein binding
directly_involved_in:
- id: GO:0006979
label: response to oxidative stress
locations:
- id: GO:0005737
label: cytoplasm
supported_by:
- reference_id: PMID:26278368
supporting_text: PpPrx and PaPrx can alternatively function as a peroxidase and chaperone
- reference_id: PMID:26278368
supporting_text: PpPrx predominates with a high molecular weight (HMW) complex and
- reference_id: file:PSEPK/PP_1084/PP_1084-deep-research-falcon.md
supporting_text: enriched in **high-molecular-weight (HMW)** oligomeric complexes, demonstrated by suppression of thermal aggregation of model substrates (e.g., malate dehydrogenase), consistent with a
proposed_new_terms: []
suggested_questions:
- question: Under which physiological oxidative-stress conditions in KT2440 does TsaA/PpPrx shift between the HMW chaperone-active and LMW peroxidase-active oligomeric states, and what is the in vivo balance of these two functions?
experts:
- Bacterial oxidative stress experts
- question: Does KT2440 TsaA reduce organic hydroperoxides and peroxynitrite in addition to H2O2, as predicted from AhpC/Prx1 subfamily membership?
experts:
- Peroxiredoxin enzymology experts
suggested_experiments:
- description: Measure peroxide-reduction kinetics (H2O2 and organic hydroperoxides) and oligomeric state changes for purified TsaA under peroxide and thioredoxin/thioredoxin-reductase conditions, using size-exclusion chromatography to resolve HMW versus LMW species.
experiment_type: redox enzyme assay
- description: Assess molecular chaperone (holdase) activity of purified TsaA by thermal- and chemical-aggregation suppression assays with model substrates, correlating activity with oligomeric state and redox conditions.
experiment_type: chaperone aggregation-suppression assay