| Property/Concept | Reported value(s) | Experimental context/method | Organism/protein variant | Citation (with URL and year) |
|---|---|---|---|---|
| Target identity / gene-symbol verification | lanM encodes Lanmodulin (LanM), a lanthanide-binding EF-hand protein; discovered in *Methylorubrum extorquens* AM1 and described as a calmodulin-like protein involved in Ln binding | Review of primary discovery literature and lanthanide biology context | *Methylorubrum extorquens* AM1 (UniProt C5B164-relevant protein) | Cotruvo 2019, https://doi.org/10.1021/acscentsci.9b00642 (2019) (pqac-00000002) |
| EF-hand architecture | 4 EF-hand motifs total; 3 high-affinity Ln-binding sites (EF1-EF3); EF4 has very low Ln affinity | Structural/biophysical synthesis; luminescence and spectroscopy-supported mapping of binding sites | LanM from *M. extorquens* AM1 | Glass et al. 2020, https://doi.org/10.1093/femsle/fnaa165 (2020); Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000000, pqac-00000011, pqac-00000008) |
| Metal-binding loop features | Canonical EF-hand metal ligands at positions 1, 3, 5, 7, 12; unusual conserved Asp at position 9 linked to very high Ln affinity; proline at position 2 may reduce Ca responsiveness | Sequence/structure analysis summarized from discovery work | LanM from *M. extorquens* AM1 | Glass et al. 2020, https://doi.org/10.1093/femsle/fnaa165 (2020) (pqac-00000000) |
| Periplasmic localization evidence | Predicted signal peptide with cleavage near E23 or K25; LanM described as periplasmic; GFP-tag/confocal localization of homolog supports periplasmic localization | Signal-peptide prediction; fluorescence microscopy/localization experiments in homolog study | *Methylobacterium aquaticum* 22A homolog compared with AM1 LanM | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000001, pqac-00000005, pqac-00000006) |
| Stoichiometry of Ln binding | ~3.65 mol La3+ per LanM molecule; commonly described as binding 3 equivalents of Ln/Tb per protein | ICP-MS with gel filtration for La; Tb preloading/luminescence studies for 3-site occupancy | 22A LanM homolog; AM1 LanM and Trp-LanM variants | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022); Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000001, pqac-00000010, pqac-00000008) |
| Ln over Ca selectivity | ~10^8-fold selectivity for lanthanides/Y3+ over Ca2+ and other tested divalent metals; Ln affinity picomolar while Ca2+ affinity millimolar | Biophysical characterization and review synthesis | LanM from *M. extorquens* AM1 | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022); Daumann et al. 2022, https://doi.org/10.1016/bs.ampbs.2022.06.001 (2022); Liu et al. 2021, https://doi.org/10.1039/d1cp03628a (2021) (pqac-00000003, pqac-00000002, pqac-00000011) |
| Ln binding affinity class | Picomolar apparent affinity for REEs; third site somewhat weaker but still very tight | Cooperative luminescence/CD analyses summarized in kinetic/sensing study | AM1 LanM / Trp-LanM variants | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000008, pqac-00000010) |
| Association kinetics | kon approximately 3-8 × 10^8 M^-1 s^-1; nearly diffusion-limited (~10^9 M^-1 s^-1) | Stopped-flow fluorescence with Tb3+ binding to Trp-engineered LanM | T41W and T90W LanM variants derived from AM1 LanM | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000009, pqac-00000010) |
| Dissociation kinetics | koff approximately 0.02-0.05 s^-1 for Tb3+ complexes | Stopped-flow fluorescence/EGTA chase | T41W and T90W LanM variants derived from AM1 LanM | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000008, pqac-00000009, pqac-00000010) |
| Solvent coordination in metal sites | Approximately 2 solvent molecules per site (values reported around 2.0 ± 0.1, 1.4 ± 0.1, 2.6 ± 0.1 depending on site/probe) | Luminescence lifetime analysis | Trp-LanM variants of AM1 LanM | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000010) |
| Apparent affinity example from site-resolved analysis | One reported phase with Kd,app ~100 pM | CD/LRET context in site-resolved binding analysis | Trp-LanM variants | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000010) |
| Actinide affinity / comparison to lanthanides | Kd = 1.3 pM for Am3+-LanM and 1.2 pM for Cm3+-LanM at pH 5.0; compared with ~10-20 pM for Pr3+, Nd3+, Sm3+ complexes | Spectroscopic competition measurements in engineered-selectivity study | AM1 LanM framework / LanM variants | Mattocks et al. 2022, https://doi.org/10.1039/d2sc01261h (2022) (pqac-00000007) |
| Engineered selectivity tuning | Asn substitution at position 9 nearly doubles actinide-vs-lanthanide selectivity; coordinated water enhances affinity and pH stability | Variant spectroscopy and mechanistic analysis | LanM variants | Mattocks et al. 2022, https://doi.org/10.1039/d2sc01261h (2022) (pqac-00000007) |
| Sensor performance in acidic real-world sample | Quantified 3 ppb (18 nM) Tb directly in acid mine drainage at pH 3.2 with 100-fold excess other REEs and 100,000-fold excess other metals | Sensitized Tb luminescence biosensing using Trp-LanM; plate-reader assay | Trp-substituted LanM variants from AM1 LanM | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000008) |
| Sensor LOD across pH | LODs below 5 ppb across pH 3-7 at 1 µM protein; example T41W-LanM LOD 1.52 ± 0.03 at pH 7 | Calibration curves and Table 2 in Tb sensing study | T41W/T90W LanM variants | Featherston et al. 2021, https://doi.org/10.1021/jacs.1c06360 (2021) (pqac-00000009, pqac-00000013) |
| Proposed physiological function | Periplasmic Ln mediator/shuttle involved in lanthanide trafficking/homeostasis and likely discrimination of Ln3+ from Ca2+; implicated in delivery toward uptake/utilization machinery rather than catalysis | Functional inference from localization, expression, and lanthanide biology studies/reviews | AM1 LanM and methylobacterial homologs | Daumann et al. 2022, https://doi.org/10.1016/bs.ampbs.2022.06.001 (2022); Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000002, pqac-00000003, pqac-00000006) |
| Relationship to MDH lanthanide switch | LanM influences regulation/homeostasis linked to the XoxF/MxaF methanol dehydrogenase switch, but is not strictly required for Ln-dependent methanol growth in tested homolog systems; AM1 deletion studies likewise did not show a clear growth defect | Genetic/physiological studies and review synthesis | AM1 and *M. aquaticum* 22A homolog system | Daumann et al. 2022, https://doi.org/10.1016/bs.ampbs.2022.06.001 (2022); Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000002, pqac-00000006) |
| Regulatory control of lanM | lanM expression induced by La3+ (~4.25-fold by RNA-seq; ~10.3-fold by qPCR on methanol + La3+); regulation linked to mxcQE and tonB_Ln | RNA-seq, qPCR, promoter/regulatory analyses | *M. aquaticum* 22A LanM homolog | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000001, pqac-00000004) |
| ΔlanM phenotype: growth requirement | No essential requirement for wild-type methylotrophic growth or XoxF-dependent growth under tested conditions | Deletion mutant growth assays | *M. aquaticum* 22A LanM homolog | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000001, pqac-00000006) |
| ΔlanM phenotype: cell envelope / La handling | ΔlanM shows aggregation upon La exposure, increased membrane permeability, rapid CFU decline after La addition, and periplasmic La deposition | Aggregation assays, EthD-III permeability, CFU time course, TEM/EDS | *M. aquaticum* 22A LanM homolog | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000004, pqac-00000006) |
| ΔlanM phenotype: vesicle-linked La homeostasis | Evidence suggests lower La in membrane-vesicle fractions in ΔlanM and higher MV-associated La in LanM-overexpressing cells, supporting a role in La efflux/homeostasis | MV isolation with ICP-MS; comparative physiology | *M. aquaticum* 22A LanM homolog | Fujitani et al. 2022, https://doi.org/10.3389/fmicb.2022.921636 (2022) (pqac-00000005, pqac-00000006) |
| Interaction with other periplasmic lanthanide proteins | Apo-LanD binds apo-LanM with Kd 4.0 ± 1.9 µM and apparent 1:1 stoichiometry; supports LanM participation in a broader periplasmic Ln-trafficking network | Protein-protein interaction/transfer study | LanD/LanM system in lanthanide uptake cluster | Larrinaga et al. 2024, https://doi.org/10.1073/pnas.2410926121 (2024) (pqac-00000012) |


*Table: This table compiles the main quantitative properties, localization evidence, physiological roles, and recent application-relevant measurements for Lanmodulin (LanM) associated with UniProt C5B164 and close methylobacterial homolog studies. It is useful as a compact evidence map linking functional annotation claims to specific experiments and citations.*