Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: Correct - Fae is localized to the cytoplasm where it catalyzes formaldehyde activation [file:METEA/fae/fae-uniprot.txt, "SUBCELLULAR LOCATION: Cytoplasm"]. Reason: UniProt records cytoplasmic localization from cell-fractionation work (PubMed:11073907), and the falcon deep research independently places the Fae reaction in the cytosol, where intracellular formaldehyde condenses with H4MPT. Supporting Evidence: file:METEA/fae/fae-deep-research-falcon.md formaldehyde entering the cytoplasm condenses with H4MPT
GO:0006730 one-carbon metabolic process	IEA GO_REF:0000043	ACCEPT	Summary: Correct - Fae is central to C1 metabolism, catalyzing the first step in formaldehyde processing [file:METEA/fae/fae-uniprot.txt, "One-carbon metabolism" and "essential enzyme for methylotrophic energy metabolism"]. Reason: The falcon deep research confirms Fae performs the first committed step of the H4MPT-linked C1 transfer pathway, channeling the C1 unit into central one-carbon metabolism. fae null mutants cannot grow on methanol, demonstrating the central metabolic role. Supporting Evidence: file:METEA/fae/fae-deep-research-falcon.md Fae performs the first committed step of the H4MPT-linked formaldehyde oxidation/detoxification pathway in AM1 file:METEA/fae/fae-deep-research-falcon.md fae null mutants are incapable of growth on methanol
GO:0009636 response to toxic substance	IEA GO_REF:0000043	ACCEPT	Summary: Correct - Fae detoxifies formaldehyde, a highly reactive and toxic metabolite [file:METEA/fae/fae-uniprot.txt, "essential enzyme for...formaldehyde detoxification"]. Reason: The falcon deep research documents the genetic basis for the detoxification role - fae mutants show methanol sensitivity during growth on succinate, interpreted as a failure to detoxify formaldehyde produced from methanol oxidation. Supporting Evidence: file:METEA/fae/fae-deep-research-falcon.md methanol sensitivity during growth on succinate
GO:0016051 carbohydrate biosynthetic process	IEA GO_REF:0000002	REMOVE	Summary: Incorrect - While Fae works with H4MPT (which contains a pterin moiety), it does not participate in carbohydrate biosynthesis. Its function is formaldehyde activation for C1 metabolism.
GO:0016829 lyase activity	IEA GO_REF:0000043	MODIFY	Summary: The direction is correct but the term is over-general. Fae is EC 4.2.1.147, a hydro-lyase (the .2.1 EC subclass corresponds to hydro-lyases that eliminate water), and the UniProt RecName is "5,6,7,8-tetrahydromethanopterin hydro-lyase" [file:METEA/fae/fae-uniprot.txt, "5,6,7,8-tetrahydromethanopterin hydro-lyase"]. The reaction condenses formaldehyde with H4MPT to methylene-H4MPT; in the lyase direction it eliminates water across a carbon-oxygen bond. The more specific MF term GO:0016836 (hydro-lyase activity) better captures this than the root-level GO:0016829 (lyase activity). Reason: GO:0016829 (lyase activity) is too general; GO:0016836 (hydro-lyase activity, "cleavage of a carbon-oxygen bond by elimination of water") precisely matches the EC 4.2.1 subclass and the UniProt hydro-lyase designation. No GO MF term exists for the exact EC 4.2.1.147 reaction, so hydro-lyase activity is the most specific applicable term. Proposed replacements: hydro-lyase activity Supporting Evidence: file:METEA/fae/fae-deep-research-falcon.md condensation of free formaldehyde with the C1 carrier cofactor H4MPT to form methylene-H4MPT
GO:0016840 carbon-nitrogen lyase activity	IEA GO_REF:0000002	REMOVE	Summary: Incorrect - Fae is a hydro-lyase, not a carbon-nitrogen lyase. It catalyzes addition of formaldehyde to H4MPT with elimination of water, not cleavage of C-N bonds. Reason: This InterPro2GO (GO_REF:0000002) prediction is a misclassification. The falcon deep research and UniProt both establish the reaction as condensation of formaldehyde with H4MPT (a hydro-lyase, EC 4.2.1.147), not a carbon-nitrogen lyase. The correct MF is GO:0016836 (hydro-lyase activity), proposed as the replacement for the over-general GO:0016829 above. Supporting Evidence: file:METEA/fae/fae-deep-research-falcon.md condensation of free formaldehyde with the C1 carrier cofactor H4MPT to form methylene-H4MPT
GO:0046294 formaldehyde catabolic process	IEA GO_REF:0000041	ACCEPT	Summary: Correct - Fae catalyzes the first step in formaldehyde degradation via the H4MPT route [file:METEA/fae/fae-uniprot.txt, "One-carbon metabolism; formaldehyde degradation; formate from formaldehyde (H4MPT route): step 1/5"]. Reason: The falcon deep research confirms Fae performs the first committed step of the H4MPT-linked formaldehyde oxidation/detoxification pathway, the primary route for formaldehyde oxidation toward formate/CO2 in AM1. Supporting Evidence: file:METEA/fae/fae-deep-research-falcon.md Fae performs the first committed step of the H4MPT-linked formaldehyde oxidation/detoxification pathway in AM1

Core Functions

Fae catalyzes the critical first step in formaldehyde metabolism by condensing formaldehyde with tetrahydromethanopterin (H4MPT) to form 5,10-methylenetetrahydromethanopterin. This reaction serves dual purposes: (1) detoxifying the highly reactive formaldehyde produced by methanol dehydrogenases, and (2) channeling the C1 unit into central metabolism for biosynthesis and energy generation. The enzyme functions as a homopentamer and is absolutely essential for growth on methanol. While the reaction proceeds spontaneously, Fae accelerates it substantially, with optimal activity at pH 7-7.5 and a KM of 0.2 mM for formaldehyde.

Molecular Function:

hydro-lyase activity

Directly Involved In:

formaldehyde catabolic process one-carbon metabolic process response to toxic substance

Cellular Locations:

cytoplasm

Supporting Evidence:

file:METEA/fae/fae-uniprot.txt
Catalyzes the condensation of formaldehyde with tetrahydromethanopterin (H4MPT) to 5,10-methylenetetrahydromethanopterin... Is an essential enzyme for methylotrophic energy metabolism and formaldehyde detoxification... Homopentamer...Optimum pH is 7-7.5...KM=0.2 mM for formaldehyde
file:METEA/fae/fae-deep-research-falcon.md
Fae performs the **first committed step** of the **H4MPT-linked formaldehyde oxidation/detoxification pathway** in AM1
file:METEA/fae/fae-deep-research-falcon.md
spontaneous condensation can occur, but Fae is the physiologically important catalyst
file:METEA/fae/fae-deep-research-falcon.md
fae null mutants are incapable of growth on methanol

References

file:METEA/fae/fae-deep-research-falcon.md

Falcon deep research report: fae (Q9FA38) in Methylorubrum extorquens AM1

"condensation of free formaldehyde with the C1 carrier cofactor H4MPT** to form **methylene-H4MPT"
"Fae performs the **first committed step** of the **H4MPT-linked formaldehyde oxidation/detoxification pathway** in AM1"
"spontaneous condensation can occur, but Fae is the physiologically important catalyst"
"fae null mutants are incapable of growth on methanol"
"methanol sensitivity during growth on succinate"
"formaldehyde entering the cytoplasm condenses with H4MPT"
"dgcB^P30L Δfae** strain showed **no growth (NG)** on glycine betaine"

file:METEA/fae/fae-uniprot.txt

UniProt entry for fae formaldehyde-activating enzyme

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms.

GO_REF:0000041

Gene Ontology annotation based on UniPathway vocabulary mapping.

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt.

Deep Research

Falcon

(fae-deep-research-falcon.md)

Research Report: **fae** (UniProt Q9FA38; META1p1766/MexAM1_META1p1766) in *Methylorubrum extorquens* AM1 Falcon Edison Scientific Literature 21 citations 2 artifacts 2026-06-03T06:19:38.366185

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000014 Table 2, titled "GB utilization phenotypes," provides information on several strains, including JB652 with the genotype $dgcB^{P30L (image/png)

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.

Research Report: fae (UniProt Q9FA38; META1p1766/MexAM1_META1p1766) in Methylorubrum extorquens AM1

0) Scope and mandatory identity verification

The target protein is UniProt Q9FA38 from Methylorubrum extorquens strain AM1 (syn. Methylobacterium extorquens AM1), annotated as 5,6,7,8-tetrahydromethanopterin hydro-lyase / formaldehyde-activating enzyme (Fae), EC 4.2.1.147. An authoritative review table mapping methylotrophy genes in AM1 lists fae in the H4MPT-dependent C1 transfer module with locus tag META1p1766, matching the UniProt-provided ordered locus name (ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5). The same sources define Fae as the enzyme catalyzing/accelerating the initial condensation step that channels formaldehyde into the H4MPT-linked pathway (marx2003formaldehydedetoxifyingroleof pages 1-2, nayak2014geneticandphenotypic pages 3-4).

1) Key concepts and current understanding (definitions and pathway context)

1.1 Formaldehyde toxicity and why methylotrophs need Fae

In aerobic methylotrophs such as M. extorquens AM1, methanol oxidation generates formaldehyde, a reactive and toxic intermediate that must be rapidly detoxified/processed to avoid growth inhibition (marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4). The dominant intracellular detoxification/oxidation route in AM1 is the tetrahydromethanopterin (H4MPT)-linked pathway (marx2003formaldehydedetoxifyingroleof pages 3-4).

1.2 Reaction catalyzed by Fae (substrates and product)

Fae catalyzes (and strongly accelerates) the condensation of free formaldehyde with the C1 carrier cofactor H4MPT to form methylene-H4MPT (the entry metabolite for subsequent H4MPT-linked oxidation steps) (marx2003formaldehydedetoxifyingroleof pages 1-2, nayak2014geneticandphenotypic pages 3-4). While the formaldehyde–H4MPT condensation can occur spontaneously, the enzyme-catalyzed reaction is described as the physiologically relevant route and is required for robust methylotrophic growth in AM1 (marx2003formaldehydedetoxifyingroleof pages 1-2).

Substrate specificity (supported by available evidence): the key substrate is formaldehyde and the key cofactor/C1 acceptor is H4MPT (marx2003formaldehydedetoxifyingroleof pages 1-2, nayak2014geneticandphenotypic pages 3-4). The provided evidence does not include detailed kinetic constants (Km, kcat) or an explicit discussion of alternative aldehyde substrates; thus, substrate specificity beyond formaldehyde cannot be asserted here.

1.3 Biological process and pathway role

Fae performs the first committed step of the H4MPT-linked formaldehyde oxidation/detoxification pathway in AM1 (marx2003formaldehydedetoxifyingroleof pages 1-2, marx2003formaldehydedetoxifyingroleof pages 2-3). In physiological terms, Fae links methanol-derived (or other metabolism-derived) intracellular formaldehyde to downstream enzymes that oxidize C1 units (ultimately toward formate/CO2, as classically described for this module) while preventing toxic formaldehyde accumulation (marx2003formaldehydedetoxifyingroleof pages 3-4).

1.4 Cellular localization and compartment of function

The H4MPT route is described as operating on formaldehyde that enters the cytoplasm, where it condenses with H4MPT (marx2003formaldehydedetoxifyingroleof pages 1-2). On that basis, the most defensible localization for the Fae reaction is intracellular/cytosolic. No direct subcellular fractionation or imaging evidence for Fae localization was identified in the retrieved evidence.

2) Gene-specific evidence in M. extorquens AM1 (primary literature)

2.1 Essentiality for methylotrophic growth on methanol

In M. extorquens AM1, fae null mutants are incapable of growth on methanol (marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4). This is strong genetic evidence that Fae is required for methylotrophic metabolism under the tested conditions and supports its central functional annotation (marx2003formaldehydedetoxifyingroleof pages 2-3).

2.2 Formaldehyde detoxification: methanol/formaldehyde sensitivity on multicarbon substrates

A hallmark phenotype of AM1 mutants defective in the H4MPT-linked pathway (including fae mutants) is methanol sensitivity during growth on succinate, interpreted as a failure to detoxify formaldehyde produced from methanol oxidation (marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4). Quantitatively, Marx et al. used plate-based assays spanning methanol concentrations up to 125 mM, where 125 mM methanol abolished growth of tested H4MPT-pathway mutant strains, and reported inhibition differences at lower methanol (e.g., 1 mM methanol) (marx2003formaldehydedetoxifyingroleof pages 3-4). They also tested formaldehyde directly (down to 0.005 mM in the assay range) to probe toxicity sensitivity (marx2003formaldehydedetoxifyingroleof pages 3-4).

2.3 Interpretation: primary but not necessarily the only possible formaldehyde-oxidation entry point

Marx et al. concluded the H4MPT-linked pathway is the primary formaldehyde oxidation/detoxification route in AM1 (marx2003formaldehydedetoxifyingroleof pages 3-4). This “primary route” framing is consistent with the idea that alternative formaldehyde-oxidation strategies can exist (or be engineered/introduced) but that, in the native AM1 network, H4MPT/Fae is central to handling cytosolic formaldehyde generated during methylotrophic growth (marx2003formaldehydedetoxifyingroleof pages 3-4).

3) Structural/biochemical evidence and expert synthesis

A widely cited review on M. extorquens methylotrophy and biotechnology notes that an AM1 Fae structure has been determined (“structure of the tetrahydromethanopterin-dependent formaldehyde-activating enzyme (Fae) from M. extorquens AM1”), supporting the enzyme’s role in binding H4MPT and catalyzing the formaldehyde activation step (ochsner2015methylobacteriumextorquensmethylotrophy pages 7-9). The review also places fae/META1p1766 explicitly in the H4MPT-dependent module, reflecting community consensus on function and pathway placement (ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5).

Because the dedicated structural paper itself was not retrievable in the current tool context, specific mechanistic/active-site claims (e.g., residue-level catalytic mechanism) are not reproduced here.

4) Recent developments (2023–2024 prioritized)

4.1 2024: Glycine betaine catabolism generates formaldehyde that requires Fae/H4MPT processing

A 2024 Applied and Environmental Microbiology study shows that in Methylorubrum extorquens PA1, enabling glycine betaine (GB) utilization produces free formaldehyde, and that this formaldehyde is handled via methylotrophy-associated machinery including H4MPT-pathway genes (hying2024glycinebetainemetabolism pages 6-9, hying2024glycinebetainemetabolism pages 9-11). Critically, a strain carrying dgcB^P30L Δfae shows no growth (NG) on GB as sole carbon/energy source (Table 2) (hying2024glycinebetainemetabolism pages 4-6, hying2024glycinebetainemetabolism media ad9482fc). This provides modern, experimentally anchored support for the broader principle that Fae-mediated formaldehyde activation is not only relevant to methanol, but also to other methylated substrates whose catabolism releases formaldehyde.

Quantitative/statistical elements available from retrieved evidence: Hying et al. report a formaldehyde assay showing increased supernatant formaldehyde in GB-grown versus pyruvate-grown cultures (figure referenced in text) and tabulate growth phenotypes (including “NG” for Δfae) (hying2024glycinebetainemetabolism pages 6-9, hying2024glycinebetainemetabolism media ad9482fc). The retrieved text snippets do not provide the exact formaldehyde concentrations or p-values.

4.2 2023: Redundancy and pathway modularity in plant-associated Methylobacterium

A 2023 Frontiers in Microbiology study on Methylobacterium aquaticum strain 22A describes that the H4MPT-linked pathway begins with Fae, and that strain 22A contains two fae homologs (fae1 and fae2); combined disruption of formaldehyde oxidation capacity (H4MPT and glutathione-linked components) produces strong formaldehyde toxicity phenotypes and methanol-associated growth defects (tani2023metabolismlinkedmethylotaxissensors pages 3-5). While not AM1-specific, it highlights contemporary interest in pathway redundancy and formaldehyde control in plant-associated methylotroph ecology.

5) Applications and real-world implementations

5.1 Biotechnological platform relevance of AM1 methylotrophy modules (including fae)

A comprehensive review (2015; Applied Microbiology and Biotechnology) frames M. extorquens AM1 as a well-characterized methylotrophic platform with biotechnological applications and summarizes the genetic modules for methylotrophy, including the H4MPT-dependent pathway with fae/META1p1766 (ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5). In application-oriented terms, Fae is part of the core “formaldehyde handling” machinery that must be functional (or deliberately rewired) when methanol or other formaldehyde-generating substrates are used as feedstocks (ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5).

5.2 Plant-associated substrate utilization intersects with formaldehyde detoxification

The 2024 glycine betaine work provides a concrete example of how plant-associated compounds (GB) can feed into formaldehyde metabolism and require Fae/H4MPT-dependent processing (hying2024glycinebetainemetabolism pages 6-9, hying2024glycinebetainemetabolism media ad9482fc). This supports real-world ecological relevance (phyllosphere carbon sources) and informs metabolic engineering: successful growth on such substrates requires maintaining efficient formaldehyde activation/oxidation capacity (hying2024glycinebetainemetabolism pages 6-9).

6) Relevant data and statistics (from retrieved evidence)

AM1 methanol/formaldehyde sensitivity assays: H4MPT-pathway mutants including fae were tested across methanol concentrations up to 125 mM, with 125 mM methanol abolishing growth in succinate-based assays; differences in inhibition were noted at 1 mM methanol (marx2003formaldehydedetoxifyingroleof pages 3-4). Formaldehyde was also tested directly down to 0.005 mM in the assay range (marx2003formaldehydedetoxifyingroleof pages 3-4).
PA1 methylamine physiology (contextual quantitative evidence): Disrupting H4MPT biosynthesis (ΔmptG) caused a 23% slower growth on succinate when methylamine was used as nitrogen source vs NH4+ (p<0.001), compared with 11% slower for WT (p=0.001) (nayak2014physiologyandevolution pages 63-67). These data support the quantitative importance of H4MPT-linked formaldehyde handling, and that loss of fae can be a partial lesion because spontaneous condensation can occur (nayak2014physiologyandevolution pages 63-67).
2024 GB phenotype table: dgcB^P30L Δfae is explicitly reported as no growth (NG) on glycine betaine (hying2024glycinebetainemetabolism media ad9482fc).

7) Evidence-based functional annotation summary (recommended)

Gene/protein	Verified identity	Reaction catalyzed	Substrates / cofactors	Pathway / module	Key genetic evidence in Methylorubrum extorquens AM1	Recent 2024 evidence / broader relevance	Localization / compartment	Key references
fae; UniProt Q9FA38; locus META1p1766 / MexAM1_META1p1766	Matches the canonical formaldehyde-activating enzyme (Fae) annotation in M. extorquens AM1; reviews/tables place fae/META1p1766 in the H4MPT-dependent C1 transfer module as a formaldehyde-activating enzyme (ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5)	Catalyzes/strongly accelerates condensation of formaldehyde + tetrahydromethanopterin (H4MPT) to form methylene-H4MPT, the entry step into the H4MPT-linked oxidation route; spontaneous condensation can occur, but Fae is the physiologically important catalyst (marx2003formaldehydedetoxifyingroleof pages 1-2, nayak2014geneticandphenotypic pages 3-4)	Formaldehyde is the C1 substrate and H4MPT is the C1 carrier/cofactor acceptor; product is methylene-H4MPT feeding downstream H4MPT enzymes (marx2003formaldehydedetoxifyingroleof pages 1-2, nayak2014geneticandphenotypic pages 3-4)	Central entry enzyme of the H4MPT-linked formaldehyde oxidation/detoxification pathway, the primary route for formaldehyde oxidation in AM1 during methylotrophic growth; pathway converts toxic intracellular formaldehyde toward formate/CO2 via downstream H4MPT enzymes (marx2003formaldehydedetoxifyingroleof pages 1-2, marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4)	fae null mutants cannot grow on methanol and are methanol/formaldehyde sensitive during growth on succinate, supporting a formaldehyde detoxification role. In plate assays, all tested H4MPT-pathway mutants were unable to grow on methanol; 1 mM methanol inhibited pathway mutants and 125 mM methanol abolished growth of tested mutants in succinate-based assays (marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4)	In 2024, glycine betaine catabolism in M. extorquens PA1 was shown to generate free formaldehyde that must be processed by methylotrophy machinery; a dgcB^P30L Δfae strain showed no growth (NG) on glycine betaine, linking Fae-dependent H4MPT chemistry to detoxification/energy capture from non-methanol substrates that release formaldehyde (hying2024glycinebetainemetabolism pages 6-9, hying2024glycinebetainemetabolism pages 4-6, hying2024glycinebetainemetabolism media ad9482fc)	Evidence places the reaction in the cytoplasm / intracellular soluble compartment, because formaldehyde entering the cytoplasm condenses with H4MPT and the H4MPT pathway is described as the intracellular primary oxidation/detoxification route; no evidence for secretion or membrane localization was identified here (marx2003formaldehydedetoxifyingroleof pages 1-2)	Marx et al., 2003, J. Bacteriol. DOI: https://doi.org/10.1128/jb.185.23.7160-7168.2003 (marx2003formaldehydedetoxifyingroleof pages 1-2, marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4); Nayak & Marx, 2014, PLoS ONE DOI: https://doi.org/10.1371/journal.pone.0107887 (nayak2014geneticandphenotypic pages 3-4); Ochsner et al., 2015, Appl. Microbiol. Biotechnol. DOI: https://doi.org/10.1007/s00253-014-6240-3 (ochsner2015methylobacteriumextorquensmethylotrophy pages 7-9, ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5); Hying et al., 2024, Appl. Environ. Microbiol. DOI: https://doi.org/10.1128/aem.02090-23 (hying2024glycinebetainemetabolism pages 6-9, hying2024glycinebetainemetabolism pages 4-6, hying2024glycinebetainemetabolism media ad9482fc)

Table: This table summarizes the verified identity, catalytic role, pathway placement, localization, and key genetic evidence for Methylorubrum extorquens AM1 Fae (Q9FA38). It also includes recent 2024 evidence linking Fae-dependent formaldehyde handling to glycine betaine metabolism.

Proposed functional statement

Fae (Q9FA38; META1p1766) is a cytosolic enzyme that catalyzes/accelerates the condensation of formaldehyde with H4MPT to form methylene-H4MPT, initiating the H4MPT-linked formaldehyde oxidation/detoxification pathway required for methylotrophic growth on methanol and for resisting formaldehyde stress in M. extorquens AM1 (marx2003formaldehydedetoxifyingroleof pages 1-2, marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4).

8) Visual evidence

Hying et al. (2024) Table 2 provides direct phenotypic support that deleting fae abolishes growth on a formaldehyde-generating substrate (glycine betaine) in M. extorquens PA1 background, supporting the functional importance of Fae-mediated formaldehyde activation/processing (hying2024glycinebetainemetabolism media ad9482fc).

9) Limitations of this report (what could not be confirmed from retrieved full text)

No kinetic parameters (Km/kcat) for AM1 Fae and no direct biochemical substrate range tests were available in the retrieved evidence snippets; therefore, the report restricts specificity claims to formaldehyde/H4MPT condensation (marx2003formaldehydedetoxifyingroleof pages 1-2, nayak2014geneticandphenotypic pages 3-4).
The existence of a solved AM1 Fae structure is supported by an authoritative review citation, but the primary structural paper could not be retrieved here, preventing residue-level mechanistic summarization (ochsner2015methylobacteriumextorquensmethylotrophy pages 7-9).

Key references (with publication dates and URLs)

Marx CJ, Chistoserdova L, Lidstrom ME. 2003-12. “Formaldehyde-Detoxifying Role of the Tetrahydromethanopterin-Linked Pathway in Methylobacterium extorquens AM1.” Journal of Bacteriology. https://doi.org/10.1128/jb.185.23.7160-7168.2003 (marx2003formaldehydedetoxifyingroleof pages 2-3, marx2003formaldehydedetoxifyingroleof pages 3-4)
Nayak DD, Marx CJ. 2014-09. “Genetic and phenotypic comparison of facultative methylotrophy between Methylobacterium extorquens strains PA1 and AM1.” PLoS ONE. https://doi.org/10.1371/journal.pone.0107887 (nayak2014geneticandphenotypic pages 3-4)
Ochsner AM, Sonntag F, Buchhaupt M, Schrader J, Vorholt JA. 2015-11. “Methylobacterium extorquens: methylotrophy and biotechnological applications.” Applied Microbiology and Biotechnology. https://doi.org/10.1007/s00253-014-6240-3 (ochsner2015methylobacteriumextorquensmethylotrophy pages 7-9, ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5)
Hying ZT, Miller TJ, Loh CY, Bazurto JV. 2024-07. “Glycine betaine metabolism is enabled in Methylorubrum extorquens PA1 by alterations to dimethylglycine dehydrogenase.” Applied and Environmental Microbiology. https://doi.org/10.1128/aem.02090-23 (hying2024glycinebetainemetabolism pages 6-9, hying2024glycinebetainemetabolism media ad9482fc)
Tani A et al. 2023-10. “Metabolism-linked methylotaxis sensors responsible for plant colonization in Methylobacterium aquaticum strain 22A.” Frontiers in Microbiology. https://doi.org/10.3389/fmicb.2023.1258452 (tani2023metabolismlinkedmethylotaxissensors pages 3-5)

References

(ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5): Andrea M. Ochsner, Frank Sonntag, Markus Buchhaupt, Jens Schrader, and Julia A. Vorholt. Methylobacterium extorquens: methylotrophy and biotechnological applications. Applied Microbiology and Biotechnology, 99:517-534, Nov 2015. URL: https://doi.org/10.1007/s00253-014-6240-3, doi:10.1007/s00253-014-6240-3. This article has 229 citations and is from a domain leading peer-reviewed journal.
(marx2003formaldehydedetoxifyingroleof pages 1-2): Christopher J. Marx, Ludmila Chistoserdova, and Mary E. Lidstrom. Formaldehyde-detoxifying role of thetetrahydromethanopterin-linked pathway in methylobacteriumextorquensam1. Journal of Bacteriology, 185:7160-7168, Dec 2003. URL: https://doi.org/10.1128/jb.185.23.7160-7168.2003, doi:10.1128/jb.185.23.7160-7168.2003. This article has 149 citations and is from a peer-reviewed journal.
(nayak2014geneticandphenotypic pages 3-4): Dipti D. Nayak and Christopher J. Marx. Genetic and phenotypic comparison of facultative methylotrophy between methylobacterium extorquens strains pa1 and am1. PLoS ONE, 9:e107887, Sep 2014. URL: https://doi.org/10.1371/journal.pone.0107887, doi:10.1371/journal.pone.0107887. This article has 48 citations and is from a peer-reviewed journal.
(marx2003formaldehydedetoxifyingroleof pages 2-3): Christopher J. Marx, Ludmila Chistoserdova, and Mary E. Lidstrom. Formaldehyde-detoxifying role of thetetrahydromethanopterin-linked pathway in methylobacteriumextorquensam1. Journal of Bacteriology, 185:7160-7168, Dec 2003. URL: https://doi.org/10.1128/jb.185.23.7160-7168.2003, doi:10.1128/jb.185.23.7160-7168.2003. This article has 149 citations and is from a peer-reviewed journal.
(marx2003formaldehydedetoxifyingroleof pages 3-4): Christopher J. Marx, Ludmila Chistoserdova, and Mary E. Lidstrom. Formaldehyde-detoxifying role of thetetrahydromethanopterin-linked pathway in methylobacteriumextorquensam1. Journal of Bacteriology, 185:7160-7168, Dec 2003. URL: https://doi.org/10.1128/jb.185.23.7160-7168.2003, doi:10.1128/jb.185.23.7160-7168.2003. This article has 149 citations and is from a peer-reviewed journal.
(ochsner2015methylobacteriumextorquensmethylotrophy pages 7-9): Andrea M. Ochsner, Frank Sonntag, Markus Buchhaupt, Jens Schrader, and Julia A. Vorholt. Methylobacterium extorquens: methylotrophy and biotechnological applications. Applied Microbiology and Biotechnology, 99:517-534, Nov 2015. URL: https://doi.org/10.1007/s00253-014-6240-3, doi:10.1007/s00253-014-6240-3. This article has 229 citations and is from a domain leading peer-reviewed journal.
(hying2024glycinebetainemetabolism pages 6-9): Zachary T. Hying, Tyler J. Miller, Chin Yi Loh, and Jannell V. Bazurto. Glycine betaine metabolism is enabled in methylorubrum extorquens pa1 by alterations to dimethylglycine dehydrogenase. Applied and Environmental Microbiology, Jul 2024. URL: https://doi.org/10.1128/aem.02090-23, doi:10.1128/aem.02090-23. This article has 6 citations and is from a peer-reviewed journal.
(hying2024glycinebetainemetabolism pages 9-11): Zachary T. Hying, Tyler J. Miller, Chin Yi Loh, and Jannell V. Bazurto. Glycine betaine metabolism is enabled in methylorubrum extorquens pa1 by alterations to dimethylglycine dehydrogenase. Applied and Environmental Microbiology, Jul 2024. URL: https://doi.org/10.1128/aem.02090-23, doi:10.1128/aem.02090-23. This article has 6 citations and is from a peer-reviewed journal.
(hying2024glycinebetainemetabolism pages 4-6): Zachary T. Hying, Tyler J. Miller, Chin Yi Loh, and Jannell V. Bazurto. Glycine betaine metabolism is enabled in methylorubrum extorquens pa1 by alterations to dimethylglycine dehydrogenase. Applied and Environmental Microbiology, Jul 2024. URL: https://doi.org/10.1128/aem.02090-23, doi:10.1128/aem.02090-23. This article has 6 citations and is from a peer-reviewed journal.
(hying2024glycinebetainemetabolism media ad9482fc): Zachary T. Hying, Tyler J. Miller, Chin Yi Loh, and Jannell V. Bazurto. Glycine betaine metabolism is enabled in methylorubrum extorquens pa1 by alterations to dimethylglycine dehydrogenase. Applied and Environmental Microbiology, Jul 2024. URL: https://doi.org/10.1128/aem.02090-23, doi:10.1128/aem.02090-23. This article has 6 citations and is from a peer-reviewed journal.
(tani2023metabolismlinkedmethylotaxissensors pages 3-5): Akio Tani, Sachiko Masuda, Yoshiko Fujitani, Toshiki Iga, Yuuki Haruna, Shiho Kikuchi, Wang Shuaile, Haoxin Lv, Shiori Katayama, Hiroya Yurimoto, Yasuyoshi Sakai, and Junichi Kato. Metabolism-linked methylotaxis sensors responsible for plant colonization in methylobacterium aquaticum strain 22a. Frontiers in Microbiology, Oct 2023. URL: https://doi.org/10.3389/fmicb.2023.1258452, doi:10.3389/fmicb.2023.1258452. This article has 13 citations and is from a peer-reviewed journal.
(nayak2014physiologyandevolution pages 63-67): DD Nayak. Physiology and evolution of methylamine metabolism across methylobacterium extorquens strains. Unknown journal, 2014.

Artifacts

Edison artifact artifact-00
$## Context ID: pqac-00000014 Table 2, titled "GB utilization phenotypes," provides information on several strains, including JB652 with the genotype $dgcB^{P30L$

Citations

ochsner2015methylobacteriumextorquensmethylotrophy pages 4-5
marx2003formaldehydedetoxifyingroleof pages 3-4
marx2003formaldehydedetoxifyingroleof pages 1-2
marx2003formaldehydedetoxifyingroleof pages 2-3
ochsner2015methylobacteriumextorquensmethylotrophy pages 7-9
tani2023metabolismlinkedmethylotaxissensors pages 3-5
hying2024glycinebetainemetabolism pages 6-9
nayak2014physiologyandevolution pages 63-67
nayak2014geneticandphenotypic pages 3-4
hying2024glycinebetainemetabolism pages 9-11
hying2024glycinebetainemetabolism pages 4-6
https://doi.org/10.1128/jb.185.23.7160-7168.2003
https://doi.org/10.1371/journal.pone.0107887
https://doi.org/10.1007/s00253-014-6240-3
https://doi.org/10.1128/aem.02090-23
https://doi.org/10.3389/fmicb.2023.1258452
https://doi.org/10.1007/s00253-014-6240-3,
https://doi.org/10.1128/jb.185.23.7160-7168.2003,
https://doi.org/10.1371/journal.pone.0107887,
https://doi.org/10.1128/aem.02090-23,
https://doi.org/10.3389/fmicb.2023.1258452,

📄 View Raw YAML

id: Q9FA38
gene_symbol: fae
product_type: PROTEIN
taxon:
  id: NCBITaxon:272630
  label: Methylorubrum extorquens AM1
description: "fae encodes the formaldehyde-activating enzyme (5,6,7,8-tetrahydromethanopterin\
  \ hydro-lyase, EC 4.2.1.147), which catalyzes the first and critical step in formaldehyde\
  \ detoxification and metabolism. The enzyme condenses formaldehyde with tetrahydromethanopterin\
  \ (H4MPT) to form 5,10-methylenetetrahydromethanopterin, channeling formaldehyde\
  \ into the central C1 metabolic pathway. While this reaction proceeds spontaneously,\
  \ Fae catalyzes it at a substantially higher rate. The protein forms a homopentamer\
  \ in the cytoplasm and is essential for growth on methanol, as it both detoxifies\
  \ the highly reactive formaldehyde produced by methanol dehydrogenases and provides\
  \ the substrate for downstream C1 metabolism. Crystal structure has been solved\
  \ at 1.9 \xC5 resolution, revealing the mechanism of H4MPT binding and formaldehyde\
  \ activation. The enzyme exhibits optimal activity at pH 7-7.5 with a KM of 0.2\
  \ mM for formaldehyde."
existing_annotations:
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: 'Correct - Fae is localized to the cytoplasm where it catalyzes formaldehyde
      activation [file:METEA/fae/fae-uniprot.txt, "SUBCELLULAR LOCATION: Cytoplasm"].'
    action: ACCEPT
    reason: UniProt records cytoplasmic localization from cell-fractionation work (PubMed:11073907),
      and the falcon deep research independently places the Fae reaction in the cytosol,
      where intracellular formaldehyde condenses with H4MPT.
    supported_by:
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: formaldehyde entering the cytoplasm condenses with H4MPT
      reference_section_type: OTHER
- term:
    id: GO:0006730
    label: one-carbon metabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: Correct - Fae is central to C1 metabolism, catalyzing the first step
      in formaldehyde processing [file:METEA/fae/fae-uniprot.txt, "One-carbon metabolism"
      and "essential enzyme for methylotrophic energy metabolism"].
    action: ACCEPT
    reason: The falcon deep research confirms Fae performs the first committed step
      of the H4MPT-linked C1 transfer pathway, channeling the C1 unit into central
      one-carbon metabolism. fae null mutants cannot grow on methanol, demonstrating
      the central metabolic role.
    supported_by:
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: Fae performs the **first committed step** of the **H4MPT-linked
        formaldehyde oxidation/detoxification pathway** in AM1
      reference_section_type: OTHER
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: fae null mutants are incapable of growth on methanol
      reference_section_type: OTHER
- term:
    id: GO:0009636
    label: response to toxic substance
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: Correct - Fae detoxifies formaldehyde, a highly reactive and toxic metabolite
      [file:METEA/fae/fae-uniprot.txt, "essential enzyme for...formaldehyde detoxification"].
    action: ACCEPT
    reason: The falcon deep research documents the genetic basis for the detoxification
      role - fae mutants show methanol sensitivity during growth on succinate, interpreted
      as a failure to detoxify formaldehyde produced from methanol oxidation.
    supported_by:
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: methanol sensitivity during growth on succinate
      reference_section_type: OTHER
- term:
    id: GO:0016051
    label: carbohydrate biosynthetic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: Incorrect - While Fae works with H4MPT (which contains a pterin moiety),
      it does not participate in carbohydrate biosynthesis. Its function is formaldehyde
      activation for C1 metabolism.
    action: REMOVE
- term:
    id: GO:0016829
    label: lyase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: 'The direction is correct but the term is over-general. Fae is EC 4.2.1.147,
      a hydro-lyase (the .2.1 EC subclass corresponds to hydro-lyases that eliminate
      water), and the UniProt RecName is "5,6,7,8-tetrahydromethanopterin hydro-lyase"
      [file:METEA/fae/fae-uniprot.txt, "5,6,7,8-tetrahydromethanopterin hydro-lyase"].
      The reaction condenses formaldehyde with H4MPT to methylene-H4MPT; in the lyase
      direction it eliminates water across a carbon-oxygen bond. The more specific
      MF term GO:0016836 (hydro-lyase activity) better captures this than the root-level
      GO:0016829 (lyase activity).'
    action: MODIFY
    reason: GO:0016829 (lyase activity) is too general; GO:0016836 (hydro-lyase activity,
      "cleavage of a carbon-oxygen bond by elimination of water") precisely matches
      the EC 4.2.1 subclass and the UniProt hydro-lyase designation. No GO MF term
      exists for the exact EC 4.2.1.147 reaction, so hydro-lyase activity is the most
      specific applicable term.
    proposed_replacement_terms:
    - id: GO:0016836
      label: hydro-lyase activity
    supported_by:
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: condensation of free formaldehyde with the C1 carrier cofactor
        H4MPT** to form **methylene-H4MPT
      reference_section_type: OTHER
- term:
    id: GO:0016840
    label: carbon-nitrogen lyase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: Incorrect - Fae is a hydro-lyase, not a carbon-nitrogen lyase. It catalyzes
      addition of formaldehyde to H4MPT with elimination of water, not cleavage of
      C-N bonds.
    action: REMOVE
    reason: This InterPro2GO (GO_REF:0000002) prediction is a misclassification. The
      falcon deep research and UniProt both establish the reaction as condensation
      of formaldehyde with H4MPT (a hydro-lyase, EC 4.2.1.147), not a carbon-nitrogen
      lyase. The correct MF is GO:0016836 (hydro-lyase activity), proposed as the replacement
      for the over-general GO:0016829 above.
    supported_by:
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: condensation of free formaldehyde with the C1 carrier cofactor
        H4MPT** to form **methylene-H4MPT
      reference_section_type: OTHER
- term:
    id: GO:0046294
    label: formaldehyde catabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000041
  review:
    summary: 'Correct - Fae catalyzes the first step in formaldehyde degradation via
      the H4MPT route [file:METEA/fae/fae-uniprot.txt, "One-carbon metabolism; formaldehyde
      degradation; formate from formaldehyde (H4MPT route): step 1/5"].'
    action: ACCEPT
    reason: The falcon deep research confirms Fae performs the first committed step
      of the H4MPT-linked formaldehyde oxidation/detoxification pathway, the primary
      route for formaldehyde oxidation toward formate/CO2 in AM1.
    supported_by:
    - reference_id: file:METEA/fae/fae-deep-research-falcon.md
      supporting_text: Fae performs the **first committed step** of the **H4MPT-linked
        formaldehyde oxidation/detoxification pathway** in AM1
      reference_section_type: OTHER
core_functions:
- description: 'Fae catalyzes the critical first step in formaldehyde metabolism by
    condensing formaldehyde with tetrahydromethanopterin (H4MPT) to form 5,10-methylenetetrahydromethanopterin.
    This reaction serves dual purposes: (1) detoxifying the highly reactive formaldehyde
    produced by methanol dehydrogenases, and (2) channeling the C1 unit into central
    metabolism for biosynthesis and energy generation. The enzyme functions as a homopentamer
    and is absolutely essential for growth on methanol. While the reaction proceeds
    spontaneously, Fae accelerates it substantially, with optimal activity at pH 7-7.5
    and a KM of 0.2 mM for formaldehyde.'
  molecular_function:
    id: GO:0016836
    label: hydro-lyase activity
  directly_involved_in:
  - id: GO:0046294
    label: formaldehyde catabolic process
  - id: GO:0006730
    label: one-carbon metabolic process
  - id: GO:0009636
    label: response to toxic substance
  locations:
  - id: GO:0005737
    label: cytoplasm
  supported_by:
  - reference_id: file:METEA/fae/fae-uniprot.txt
    supporting_text: Catalyzes the condensation of formaldehyde with tetrahydromethanopterin
      (H4MPT) to 5,10-methylenetetrahydromethanopterin... Is an essential enzyme for
      methylotrophic energy metabolism and formaldehyde detoxification... Homopentamer...Optimum
      pH is 7-7.5...KM=0.2 mM for formaldehyde
  - reference_id: file:METEA/fae/fae-deep-research-falcon.md
    supporting_text: Fae performs the **first committed step** of the **H4MPT-linked
      formaldehyde oxidation/detoxification pathway** in AM1
    reference_section_type: OTHER
  - reference_id: file:METEA/fae/fae-deep-research-falcon.md
    supporting_text: spontaneous condensation can occur, but Fae is the physiologically
      important catalyst
    reference_section_type: OTHER
  - reference_id: file:METEA/fae/fae-deep-research-falcon.md
    supporting_text: fae null mutants are incapable of growth on methanol
    reference_section_type: OTHER
references:
- id: file:METEA/fae/fae-deep-research-falcon.md
  title: 'Falcon deep research report: fae (Q9FA38) in Methylorubrum extorquens AM1'
  findings:
  - supporting_text: condensation of free formaldehyde with the C1 carrier cofactor
      H4MPT** to form **methylene-H4MPT
    reference_section_type: OTHER
  - supporting_text: Fae performs the **first committed step** of the **H4MPT-linked
      formaldehyde oxidation/detoxification pathway** in AM1
    reference_section_type: OTHER
  - supporting_text: spontaneous condensation can occur, but Fae is the physiologically
      important catalyst
    reference_section_type: OTHER
  - supporting_text: fae null mutants are incapable of growth on methanol
    reference_section_type: OTHER
  - supporting_text: methanol sensitivity during growth on succinate
    reference_section_type: OTHER
  - supporting_text: formaldehyde entering the cytoplasm condenses with H4MPT
    reference_section_type: OTHER
  - supporting_text: dgcB^P30L Δfae** strain showed **no growth (NG)** on glycine betaine
    reference_section_type: OTHER
- id: file:METEA/fae/fae-uniprot.txt
  title: UniProt entry for fae formaldehyde-activating enzyme
  findings: []
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms.
  findings: []
- id: GO_REF:0000041
  title: Gene Ontology annotation based on UniPathway vocabulary mapping.
  findings: []
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt.
  findings: []
status: COMPLETE
tags:
- metea

fae

Gene Description

Existing Annotations Review

Core Functions

References

Tags

Deep Research

Falcon

Research Report: fae (UniProt Q9FA38; META1p1766/MexAM1_META1p1766) in Methylorubrum extorquens AM1

0) Scope and mandatory identity verification

1) Key concepts and current understanding (definitions and pathway context)

1.1 Formaldehyde toxicity and why methylotrophs need Fae

1.2 Reaction catalyzed by Fae (substrates and product)

1.3 Biological process and pathway role

1.4 Cellular localization and compartment of function

2) Gene-specific evidence in M. extorquens AM1 (primary literature)

2.1 Essentiality for methylotrophic growth on methanol

2.2 Formaldehyde detoxification: methanol/formaldehyde sensitivity on multicarbon substrates

2.3 Interpretation: primary but not necessarily the only possible formaldehyde-oxidation entry point

3) Structural/biochemical evidence and expert synthesis

4) Recent developments (2023–2024 prioritized)

4.1 2024: Glycine betaine catabolism generates formaldehyde that requires Fae/H4MPT processing

4.2 2023: Redundancy and pathway modularity in plant-associated Methylobacterium

5) Applications and real-world implementations

5.1 Biotechnological platform relevance of AM1 methylotrophy modules (including fae)

5.2 Plant-associated substrate utilization intersects with formaldehyde detoxification

6) Relevant data and statistics (from retrieved evidence)

7) Evidence-based functional annotation summary (recommended)

Proposed functional statement

8) Visual evidence

9) Limitations of this report (what could not be confirmed from retrieved full text)

Key references (with publication dates and URLs)

Artifacts

Citations

📄 View Raw YAML