| Topic | Key finding (1-2 sentences) | Quantitative data (if any) | Source (first author year, journal) | URL | Citation ID |
|---|---|---|---|---|---|
| Reaction | In *Methylorubrum extorquens* AM1, xoxF1 encodes a lanthanide-dependent methanol dehydrogenase that oxidizes methanol to formaldehyde. Genetic evidence links XoxF1/XoxF2 activity to formaldehyde accumulation phenotypes during methanol growth with lanthanides. | Purified XoxF1 methanol oxidation activity reported as Vmax = 0.015 U/mg. | Vu 2016, *Journal of Bacteriology*; Roszczenko-Jasińska 2020, *Scientific Reports* | https://doi.org/10.1128/jb.00937-15 ; https://doi.org/10.1038/s41598-020-69401-4 | (pqac-00000001, pqac-00000002) |
| Cofactors | XoxF1 is a PQQ-dependent alcohol dehydrogenase that requires lanthanides rather than Ca²⁺ in the active site. Lanthanides act with PQQ in the catalytic cofactor complex and facilitate alcohol oxidation. | XoxF purified from lanthanide-grown cells incorporated ~1.24 atoms of La and lacked Ca; reconstitution assays used 200 nM enzyme, 200 nM Ln, 200 nM PQQ, 50 mM methanol. | Vu 2016, *Journal of Bacteriology*; Singer 2022, *ChemRxiv* | https://doi.org/10.1128/jb.00937-15 ; https://doi.org/10.26434/chemrxiv-2022-zn3t4 | (pqac-00000008, pqac-00000006, pqac-00000022) |
| Localization | XoxF1 is described as a periplasmic PQQ-dependent alcohol dehydrogenase, consistent with methylotrophic PQQ-ADHs generally being periplasmic enzymes. It functions in a periplasm-associated lanthanide oxidation system. | No direct localization constant reported; schematic evidence places XoxF1 in the periplasm. | Roszczenko-Jasińska 2020, *Scientific Reports*; Roszczenko-Jasińska 2019, *bioRxiv* | https://doi.org/10.1038/s41598-020-69401-4 ; https://doi.org/10.1101/647677 | (pqac-00000003, pqac-00000009, pqac-00000014, pqac-00000024) |
| Regulation | AM1 exhibits a lanthanide switch in which lanthanides upregulate the xox1 operon and repress the Ca-dependent mxa operon. XoxF proteins also appear necessary for proper expression of MxaFI, indicating a regulatory role beyond catalysis. | Growth reaches maximum rate/yield at ≥1 μM La; growth still occurs at ~2.5 nM La but more slowly; intermediate mxa/xox1 co-expression occurs at 50–100 nM La. | Vu 2016, *Journal of Bacteriology*; Roszczenko-Jasińska 2020, *Scientific Reports* | https://doi.org/10.1128/jb.00937-15 ; https://doi.org/10.1038/s41598-020-69401-4 | (pqac-00000001, pqac-00000018, pqac-00000011, pqac-00000020) |
| Growth data | Loss of xoxF1 reduces methanol-growth performance in lanthanide-containing medium, and double loss of xoxF1/xoxF2 causes a stronger defect. Wild type and mxaF mutants grow similarly under La³⁺, showing XoxF-mediated methanol oxidation can support growth. | WT and mxaF growth rates ~0.16 ± 0.01 h⁻¹; xoxF1 0.07 ± 0.00 h⁻¹ with 6–9 h lag; xoxF1 xoxF2 0.04 ± 0.01 h⁻¹ with ~6 h lag. | Roszczenko-Jasińska 2020, *Scientific Reports* | https://doi.org/10.1038/s41598-020-69401-4 | (pqac-00000020) |
| Metal specificity | AM1 XoxF systems primarily use light lanthanides. La, Ce, Pr, and Nd support the lanthanide switch and methanol growth, while Sm is less effective and heavier lanthanides generally do not support growth in the wild type. | Light Ln range noted as La–Sm (atomic numbers 57–62); growth with Sm is slower; heavier Ln usually do not support growth. | Vu 2016, *Journal of Bacteriology*; Good 2022, *Frontiers in Microbiology* | https://doi.org/10.1128/jb.00937-15 ; https://doi.org/10.3389/fmicb.2022.820327 | (pqac-00000001, pqac-00000018, pqac-00000000, pqac-00000023) |
| Partners | XoxF1 functions with accessory proteins including XoxG, a cytochrome c electron acceptor, and XoxJ, a periplasmic binding protein; both are required for efficient XoxF-dependent methanol oxidation. PQQ biosynthesis and cytochrome c biogenesis genes are also essential for the pathway. | Transposon screen recovered >600 mutants; genes identified independently ≥4 times were prioritized. | Roszczenko-Jasińska 2020, *Scientific Reports*; Roszczenko-Jasińska 2019, *bioRxiv* | https://doi.org/10.1038/s41598-020-69401-4 ; https://doi.org/10.1101/647677 | (pqac-00000002, pqac-00000013, pqac-00000015) |
| Applications | The xoxF1-centered lanthanide methylotrophy system underpins AM1-based rare-earth bioaccumulation, biomining, and potentially MRI/bioremediation technologies. Engineering lanthanide uptake, lanthanophore production, PQQ biosynthesis, and phosphate metabolism enhances recovery from waste sources. | evo-HLn hyperaccumulated Gd ~36-fold; AM1-based REE recovery was scaled to 10 L; whole-cell MRI contrast was observed in Gd-hyperaccumulating cells. | Good 2022, *Frontiers in Microbiology*; Good 2023, *Environmental Science & Technology* | https://doi.org/10.3389/fmicb.2022.820327 ; https://doi.org/10.1021/acs.est.3c06775 | (pqac-00000000, pqac-00000023) |
| Comparative enzymology | Broader XoxF literature supports that REE-dependent XoxF enzymes are active methanol dehydrogenases with PQQ-like spectral signatures, alkaline assay optima, and measurable methanol activities, reinforcing the family assignment for AM1 XoxF1. These data are supportive but not AM1 xoxF1-specific kinetics. | Example XoxF5_M.e.1 kinetics: Vmax 12.5 ± 0.2 U mg⁻¹, Km 21 ± 1 mM, Keff 1,252 ± 135 s⁻¹ mM⁻¹; UV-Vis maximum ~355 nm. | Huang 2019, *The ISME Journal* | https://doi.org/10.1038/s41396-019-0414-z | (pqac-00000005) |
| Recent ecosystem-scale growth data | A 2024 ecosystem-oriented study using AM1 showed concentration-dependent growth responses to Ca²⁺ and individual lanthanides, illustrating that moderate light-lanthanide concentrations can support fast methanol growth while higher concentrations can become inhibitory. | With 125 mM methanol: La³⁺ fastest doubling 4.9 h at 1 μM; Ce³⁺ fastest doubling 2.9 h at 1 μM; 100 μM Ce³⁺ slowed doubling to 12.4 h; Ca²⁺ fastest doubling 3.7 h at 10 μM. | Warters 2024, unknown journal/thesis source | Not available from citation metadata | (pqac-00000016, pqac-00000017, pqac-00000019) |


*Table: This table compiles key functional-annotation evidence for xoxF1 (UniProt C5B120) in *Methylorubrum extorquens* AM1, covering reaction chemistry, cofactors, localization, regulation, growth phenotypes, partner proteins, metal specificity, and applications. It is designed as a quick-reference evidence map tied directly to available citation IDs.*