| Gene/protein | Proposed role | Evidence type | Key quantitative phenotype | Subcellular localization | Primary sources with year, DOI URL |
|---|---|---|---|---|---|
| **mxaD** (canonical AM1 mxa operon gene) | Accessory methanol-oxidation factor in the MOX/mxa cluster; commonly described as required for active MxaFI MDH, either by contributing to **Ca2+ insertion into MDH** or by **stimulating interaction/electron transfer between MDH and cytochrome cL** | Review/genomic annotation; operon context; biochemical inference from MDH physiology | No direct single-gene quantitative phenotype recovered in the provided excerpts for canonical **mxaD**; function is inferred from operon assignment and prior biochemical models rather than a reported growth-rate table in these contexts (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000007, pqac-00000008, pqac-00000009) | Not directly demonstrated for canonical **mxaD** in the provided excerpts | Chistoserdova et al. 2003, *J Bacteriol* — https://doi.org/10.1128/jb.185.10.2980-2987.2003 ; Anthony & Williams 2003, *Biochim Biophys Acta* — https://doi.org/10.1016/S1570-9639(03)00042-6 ; Schmidt et al. 2010, *Microbiology* — https://doi.org/10.1099/mic.0.038570-0 ; Wu et al. 2015, *Appl Environ Microbiol* — https://doi.org/10.1128/AEM.03292-14 (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000007, pqac-00000008, pqac-00000009) |
| **mxaD homolog MexAM1_META1p1771** (reported as an MxaD homolog; often interpreted as **xoxD-like**) | Contributor to **lanthanide-dependent methanol metabolism/XoxF1 function**; proposed to **directly or indirectly stimulate interaction between MxaFI-MeDH and cytochrome cL**, by homology/function analogy to MxaD | Genetic screen; targeted mutant phenotyping; functional inference by homology | In MeOH + La3+, mutant growth rate **0.11 ± 0.01 h^-1** versus wild type **0.16 ± 0.01 h^-1** (~31% lower); identified in transposon screen and retained substantial but impaired growth (pqac-00000012, pqac-00000017) | **Periplasmic** localization is reported for the **META1p1771 MxaD homolog** in the provided evidence; this localization is not directly shown for canonical mxaD in these excerpts (pqac-00000011) | Roszczenko-Jasińska et al. 2020, *Sci Rep* — https://doi.org/10.1038/s41598-020-69401-4 ; Roszczenko-Jasińska et al. 2019, *bioRxiv* — https://doi.org/10.1101/647677 (pqac-00000011, pqac-00000012, pqac-00000017) |
| **mxaD homolog MexAM1_META1p1772** (nearby homolog) | Possible paralog/redundant or specialized MxaD-like factor in lanthanide/methanol metabolism; specific role unresolved in the provided evidence | Genetic-screen observation / negative evidence | Not hit in the transposon mutagenesis screen; no growth-rate value reported in the provided excerpts (pqac-00000011) | No localization reported in the provided excerpts | Roszczenko-Jasińska et al. 2019, *bioRxiv* — https://doi.org/10.1101/647677 (pqac-00000011) |


*Table: This table summarizes evidence-supported roles, phenotypes, and localization for canonical mxaD and MxaD homologs in Methylorubrum extorquens AM1. It distinguishes direct genetic evidence for the META1p1771 homolog from more inferential literature on the canonical mxaD operon gene.*