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.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The target protein UniProt Q88M06 corresponds to Pseudomonas putida strain KT2440 PP_1769, annotated as pheA, encoding a bifunctional chorismate mutase/prephenate dehydratase (often termed the bacterial “P-protein”). This assignment is supported by direct genetic-functional analysis in KT2440 showing that insertions in PP_1769 confer phenylalanine auxotrophy and by operon mapping placing PP_1769 with other aromatic biosynthesis genes (molinahenares2009functionalanalysisof pages 6-7, molinahenares2009functionalanalysisof pages 1-2). This confirms that the gene symbol pheA matches the protein description provided (bifunctional CM/PDT enzyme).
In bacteria, chorismate is a central branch-point metabolite of the shikimate pathway. One major fate is conversion into prephenate via chorismate mutase activity; prephenate is then processed toward phenylalanine and tyrosine (dosselaere2001ametabolicnode pages 3-5). The importance of this “chorismate node” is that multiple pathways compete for chorismate, making enzymes such as PheA key control points for flux partitioning (dosselaere2001ametabolicnode pages 3-5).
Bacterial PheA proteins are two-domain (bifunctional) enzymes that couple:
- Chorismate mutase (CM; EC 5.4.99.5): catalyzes chorismate → prephenate (a Claisen rearrangement) (dosselaere2001ametabolicnode pages 3-5).
- Prephenate dehydratase (PDT; EC 4.2.1.51): converts prephenate → phenylpyruvate (the keto-acid precursor of L-phenylalanine) (dosselaere2001ametabolicnode pages 3-5).
This functional definition is consistent with Pseudomonas KT2440 genetics: disrupting PP_1769 blocks phenylalanine biosynthesis (molinahenares2009functionalanalysisof pages 6-7, molinahenares2009functionalanalysisof pages 1-2).
A central property of many bacterial PheA enzymes is allosteric feedback inhibition by L-phenylalanine. Authoritative biochemical dissection of model bacterial PheA shows a separable C-terminal regulatory region required for full phenylalanine-mediated inhibition; truncation abolishes feedback inhibition and alters substrate affinity (zhang1998chorismatemutaseprephenatedehydratase pages 5-6). Reviews of chorismate-utilizing enzymes similarly describe PheA as allosterically inhibited by phenylalanine with conformational/oligomeric effects (dosselaere2001ametabolicnode pages 3-5).
A functional genetic analysis in P. putida KT2440 found multiple independent mini-Tn5 insertions in PP_1769 (pheA) (insertions reported at codons 6, 37, 42, and 120) that produced mutants whose growth was restored by phenylalanine supplementation but not by tyrosine, demonstrating phenylalanine auxotrophy and arguing against a tyrosine→phenylalanine bypass in this organism (molinahenares2009functionalanalysisof pages 6-7). This provides organism-specific evidence that PP_1769 is required for endogenous phenylalanine synthesis.
In KT2440, PP_1769 (pheA) is tightly linked to aromatic biosynthesis genes: PP_1769 overlaps serC by 6 nucleotides and lies 61 nucleotides from PP_1770, and RT-PCR supports that pheA forms an operon with serC and also with PP_1770 (tyrA; prephenate dehydrogenase) (molinahenares2009functionalanalysisof pages 6-7). This genomic organization strengthens the functional inference that PP_1769 is part of the aromatic amino-acid biosynthetic module in KT2440.
The KT2440 mutant phenotypes demonstrate that disrupting pheA blocks phenylalanine synthesis upstream of phenylalanine formation (molinahenares2009functionalanalysisof pages 6-7). While the KT2440 papers retrieved here do not report purified-enzyme kinetics, authoritative biochemical studies of PheA family proteins show that PheA catalyzes the two-step CM/PDT route committing carbon toward phenylpyruvate (and thus L-phenylalanine) (dosselaere2001ametabolicnode pages 3-5, zhang1998chorismatemutaseprephenatedehydratase pages 3-5).
Detailed biochemical domain studies of bacterial PheA show that phenylalanine is a strong inhibitor of the dehydratase activity and that the C-terminal regulatory region is required for full feedback control (zhang1998chorismatemutaseprephenatedehydratase pages 5-6, zhang1998chorismatemutaseprephenatedehydratase pages 3-5). A chorismate-node review further describes phenylalanine binding as causing conformational changes and shifts in oligomeric state linked to decreased activity (dosselaere2001ametabolicnode pages 3-5).
A 2024 study in Pseudomonas putida DOT-T1E (a different P. putida strain, but the same enzyme class and pathway role) identified intracellular L-phenylalanine as a limiting substrate for 2-phenylethanol (2-PE) production and introduced a chorismate mutase/prephenate dehydratase variant described as insensitive to feedback inhibition by aromatic amino acids. This intervention increased phenylalanine availability and improved 2-PE titers (godoy2024biosynthesisoffragrance pages 1-2). This provides recent, experimentally supported Pseudomonas evidence that PheA-like feedback control materially constrains flux toward phenylalanine-derived products.
No direct subcellular localization experiment for KT2440 PP_1769/PheA was found in the retrieved full texts. However, the biochemical role of PheA is within core cytosolic metabolism (shikimate pathway branch), and bifunctional PheA enzymes in bacteria are typically treated as cytosolic enzymes acting on intracellular chorismate and prephenate pools (supported indirectly by the genetic/physiological phenotypes in KT2440) (molinahenares2009functionalanalysisof pages 6-7, molinahenares2009functionalanalysisof pages 1-2).
Importantly, Pseudomonas can also encode periplasm-localized monofunctional AroQ chorismate mutases (“AroQ”), shown experimentally in Pseudomonas aeruginosa as periplasmic proteins (calhoun2001theemergingperiplasmlocalized pages 1-2). These are not* the same as the KT2440 PP_1769 bifunctional PheA (which is genetically tied to cytosolic aromatic biosynthesis genes and is required for phenylalanine prototrophy). This distinction reduces risk of misannotation when interpreting chorismate mutase activity in Pseudomonads (molinahenares2009functionalanalysisof pages 6-7, calhoun2001theemergingperiplasmlocalized pages 1-2).
Godoy et al. (published April 2024) engineered P. putida DOT‑T1E strains for fragrance 2‑phenylethanol production via the Ehrlich pathway and found phenylalanine supply limiting. Introducing a feedback-insensitive CM/PDT (PheA-class) enzyme increased phenylalanine and improved 2‑PE production, and further random mutagenesis increased titers (godoy2024biosynthesisoffragrance pages 1-2). URL: https://doi.org/10.1186/s13068-024-02498-1 (godoy2024biosynthesisoffragrance pages 1-2).
Although this is not KT2440 specifically, it is a close-strain P. putida demonstration aligning with the known regulatory role of PheA and is directly relevant for functional annotation in the Pseudomonas context (godoy2024biosynthesisoffragrance pages 1-2).
Within the retrieved corpus, no 2023 primary paper directly characterizing KT2440 PP_1769/PheA biochemistry (e.g., kinetics/structure) was obtained. Therefore, KT2440-specific “latest research” in 2023 cannot be asserted here beyond engineering/physiology already cited.
A clear implementation in P. putida KT2440 is metabolic engineering for para-hydroxybenzoic acid (PHBA) production from glucose. In this strategy, pheA was deleted (along with other edits) specifically to remove competition for chorismate and redirect flux toward PHBA formation (yu2016metabolicengineeringof pages 1-3, yu2016metabolicengineeringof pages 5-6). In fed-batch fermentation, the best engineered strain achieved 1.73 g/L PHBA and 18.1% carbon yield (C-mol/C-mol) (yu2016metabolicengineeringof pages 5-6). URL: https://doi.org/10.3389/fbioe.2016.00090 (published Nov 2016) (yu2016metabolicengineeringof pages 5-6).
Conversely, when the product goal is phenylalanine-derived aromatics (e.g., 2‑phenylethanol), engineering strategies can increase flux through PheA by relieving feedback control. In P. putida DOT-T1E, introduction of a feedback-insensitive CM/PDT enzyme increased 2‑PE production and enabled use of agricultural waste-derived sugar mixtures as substrates (godoy2024biosynthesisoffragrance pages 1-2).
Reviews of chorismate-utilizing enzymes emphasize that the chorismate node is a heavily competed metabolic branchpoint, and that enzymes like PheA combine catalytic commitment with tight allosteric regulation by end products such as phenylalanine (dosselaere2001ametabolicnode pages 3-5). This explains why pheA deletions can strongly redirect chorismate to alternative products (e.g., PHBA) and why feedback-insensitive variants can boost phenylalanine supply for downstream synthesis (yu2016metabolicengineeringof pages 5-6, godoy2024biosynthesisoffragrance pages 1-2).
Biochemical domain dissection of PheA shows that the regulatory region is separable from catalytic fragments, and removal can abolish phenylalanine feedback inhibition (zhang1998chorismatemutaseprephenatedehydratase pages 5-6). This modularity underlies a common metabolic engineering tactic: creating or importing feedback-resistant variants to increase flux (as reflected in the 2024 Pseudomonas work) (godoy2024biosynthesisoffragrance pages 1-2, zhang1998chorismatemutaseprephenatedehydratase pages 5-6).
Key quantitative outcomes directly tied to manipulating the PheA node include:
- PHBA production (KT2440): 1.73 g/L maximum titer; 18.1% C-mol/C-mol carbon yield in a non-optimized fed-batch fermentation; engineering included deletion of pheA to reduce chorismate consumption by aromatic amino-acid biosynthesis (yu2016metabolicengineeringof pages 5-6, yu2016metabolicengineeringof pages 1-3).
- 2-phenylethanol production (P. putida DOT-T1E; 2024): baseline production with glucose about 50–60 ppm, increasing to about 100 ppm after introducing a feedback-insensitive CM/PDT variant, and up to 120 ppm after additional random mutagenesis (godoy2024biosynthesisoffragrance pages 1-2).
The following table consolidates direct KT2440 evidence, family-level biochemical understanding, and application-level data.
| Gene/locus | Protein name | EC numbers | Domains | Primary reactions | Pathway role | Key experimental evidence in P. putida KT2440 | Evidence of regulation | Applications | Key quantitative data | Primary source (year, URL) |
|---|---|---|---|---|---|---|---|---|---|---|
| pheA / PP_1769 / UniProt Q88M06 | Bifunctional chorismate mutase/prephenate dehydratase (“P-protein”) | EC 5.4.99.5 (chorismate mutase); EC 4.2.1.51 (prephenate dehydratase) | N-terminal chorismate mutase (CM) catalytic region; prephenate dehydratase (PDT) catalytic region; C-terminal ACT-like regulatory domain inferred from family/domain architecture and bacterial PheA literature | Chorismate → prephenate (CM step); prephenate → phenylpyruvate + H2O + CO2 (PDT step), committing flux toward phenylalanine biosynthesis (dosselaere2001ametabolicnode pages 3-5, zhang1998chorismatemutaseprephenatedehydratase pages 3-5) | Branch-point enzyme at the chorismate node directing carbon from the shikimate pathway into the phenylalanine branch; competes with other chorismate-consuming pathways | Mini-Tn5 insertions in PP_1769 caused phenylalanine auxotrophy; growth restored by phenylalanine but not tyrosine. RT-PCR showed serC–pheA–PP1770/tyrA operon linkage; PP_1769 overlaps serC by 6 nt and lies 61 nt from PP1770. Deletion of pheA in KT2440 was also used to redirect chorismate flux in engineering studies (molinahenares2009functionalanalysisof pages 6-7, molinahenares2009functionalanalysisof pages 1-2, yu2016metabolicengineeringof pages 5-6) | Canonical bacterial PheA enzymes are allosterically feedback-inhibited by L-phenylalanine, mediated by a separable C-terminal regulatory region/ACT-like domain; Phe strongly inhibits PDT activity and alters oligomerization in model bacterial PheA proteins (dosselaere2001ametabolicnode pages 3-5, zhang1998chorismatemutaseprephenatedehydratase pages 5-6, zhang1998chorismatemutaseprephenatedehydratase pages 3-5). In Pseudomonas, engineered feedback-insensitive CM/PDT (PheA) variants were introduced to raise intracellular phenylalanine and downstream product formation (godoy2024biosynthesisoffragrance pages 1-2) | PHBA production: deleting pheA in KT2440 removes competition for chorismate, improving precursor availability for para-hydroxybenzoic acid production. 2-Phenylethanol (2-PE): relieving CM/PDT feedback inhibition increased phenylalanine supply and improved 2-PE production in Pseudomonas strains (yu2016metabolicengineeringof pages 5-6, yu2016metabolicengineeringof pages 1-3, godoy2024biosynthesisoffragrance pages 1-2) | PHBA in engineered KT2440 reached 1.73 g/L maximum titer and 18.1% C-mol/C-mol carbon yield in fed-batch; strategy included pheA deletion (yu2016metabolicengineeringof pages 5-6, yu2016metabolicengineeringof pages 1-3). In Pseudomonas putida DOT-T1E derivatives, introducing a feedback-insensitive CM/PDT increased 2-PE to about 100 ppm, with random mutagenesis pushing titers to 120 ppm (godoy2024biosynthesisoffragrance pages 1-2) | Molina-Henares et al., 2009, https://doi.org/10.1111/j.1751-7915.2008.00062.x ; Yu et al., 2016, https://doi.org/10.3389/fbioe.2016.00090 ; Godoy et al., 2024, https://doi.org/10.1186/s13068-024-02498-1 |
Table: This table summarizes verified functional annotation evidence for Pseudomonas putida KT2440 pheA/PP_1769 (UniProt Q88M06), including catalytic role, operon/genetic evidence, regulation, and engineering applications. It is useful for quickly separating direct KT2440 evidence from broader family-level regulatory inference.
References
(molinahenares2009functionalanalysisof pages 6-7): M. A. Molina-Henares, Adela García‐Salamanca, A. Molina-Henares, J. de la Torre, M. C. Herrera, J. Ramos, and E. Duque. Functional analysis of aromatic biosynthetic pathways in pseudomonas putida kt2440. Microbial biotechnology, 2:91-100, Dec 2009. URL: https://doi.org/10.1111/j.1751-7915.2008.00062.x, doi:10.1111/j.1751-7915.2008.00062.x. This article has 32 citations and is from a peer-reviewed journal.
(molinahenares2009functionalanalysisof pages 1-2): M. A. Molina-Henares, Adela García‐Salamanca, A. Molina-Henares, J. de la Torre, M. C. Herrera, J. Ramos, and E. Duque. Functional analysis of aromatic biosynthetic pathways in pseudomonas putida kt2440. Microbial biotechnology, 2:91-100, Dec 2009. URL: https://doi.org/10.1111/j.1751-7915.2008.00062.x, doi:10.1111/j.1751-7915.2008.00062.x. This article has 32 citations and is from a peer-reviewed journal.
(dosselaere2001ametabolicnode pages 3-5): Filip Dosselaere and J. Vanderleyden. A metabolic node in action: chorismate-utilizing enzymes in microorganisms. Critical Reviews in Microbiology, 27:131-75, Jan 2001. URL: https://doi.org/10.1080/20014091096710, doi:10.1080/20014091096710. This article has 254 citations and is from a peer-reviewed journal.
(zhang1998chorismatemutaseprephenatedehydratase pages 5-6): S Zhang, G Pohnert, P Kongsaeree, and DB Wilson. Chorismate mutase-prephenate dehydratase from escherichia coli: study of catalytic and regulatory domains using genetically engineered proteins. Unknown journal, 1998.
(zhang1998chorismatemutaseprephenatedehydratase pages 3-5): S Zhang, G Pohnert, P Kongsaeree, and DB Wilson. Chorismate mutase-prephenate dehydratase from escherichia coli: study of catalytic and regulatory domains using genetically engineered proteins. Unknown journal, 1998.
(godoy2024biosynthesisoffragrance pages 1-2): Patricia Godoy, Zulema Udaondo, Estrella Duque, and Juan L. Ramos. Biosynthesis of fragrance 2-phenylethanol from sugars by pseudomonas putida. Biotechnology for Biofuels and Bioproducts, Apr 2024. URL: https://doi.org/10.1186/s13068-024-02498-1, doi:10.1186/s13068-024-02498-1. This article has 11 citations and is from a domain leading peer-reviewed journal.
(calhoun2001theemergingperiplasmlocalized pages 1-2): David H Calhoun, Carol A Bonner, Wei Gu, Gary Xie, and Roy A Jensen. The emerging periplasm-localized subclass of aroq chorismate mutases, exemplified by those from salmonella typhimurium and pseudomonas aeruginosa. Genome Biology, 2:research0030.1-research0030.16, Jul 2001. URL: https://doi.org/10.1186/gb-2001-2-8-research0030, doi:10.1186/gb-2001-2-8-research0030. This article has 75 citations and is from a highest quality peer-reviewed journal.
(yu2016metabolicengineeringof pages 1-3): Shiqin Yu, Manuel R. Plan, Gal Winter, and Jens O. Krömer. Metabolic engineering of pseudomonas putida kt2440 for the production of para-hydroxy benzoic acid. Frontiers in Bioengineering and Biotechnology, Nov 2016. URL: https://doi.org/10.3389/fbioe.2016.00090, doi:10.3389/fbioe.2016.00090. This article has 76 citations.
(yu2016metabolicengineeringof pages 5-6): Shiqin Yu, Manuel R. Plan, Gal Winter, and Jens O. Krömer. Metabolic engineering of pseudomonas putida kt2440 for the production of para-hydroxy benzoic acid. Frontiers in Bioengineering and Biotechnology, Nov 2016. URL: https://doi.org/10.3389/fbioe.2016.00090, doi:10.3389/fbioe.2016.00090. This article has 76 citations.