| Claim/Topic | Evidence summary | Organism/strain | Study type | Year | Source (with DOI URL) |
|---|---|---|---|---|---|
| Lanthanide-dependent model linking MxcQE/MxbDM to *mxa* vs *xox1* regulation | Peer-reviewed study proposes that MxcQE and MxbDM are two-component systems required for expression of the *mxa* genes, although directness was not demonstrated. Working model: in the absence of lanthanides, apo-XoxF activates *mxa* and represses *xox1* through MxcQE/MxbDM; in the presence of lanthanides, XoxF functions as a lanthanide-dependent methanol dehydrogenase and *mxa* is repressed while *xox1* is activated. Figures 6–7 report promoter-reporter measurements from biological triplicates across increasing La concentrations and different lanthanides, supporting lanthanide-responsive switching of *mxa* and *xox1* expression (pqac-00000003, pqac-00000007, pqac-00000011, pqac-00000012, pqac-00000013). | *Methylobacterium extorquens* AM1 (now *Methylorubrum extorquens* AM1) | Primary experimental study with promoter-reporter assays and regulatory model | 2016 | Vu et al., *Journal of Bacteriology* (2016), DOI: https://doi.org/10.1128/JB.00937-15 |
| Regulatory mutant promoter-fusion evidence implicating MxcE/MxcQ in methanol-oxidation control | In xylE transcription-fusion assays for promoters upstream of *orf3* and *orf4*, wild type showed low activity, while regulatory mutants showed elevated expression. Reported catechol 2,3-dioxygenase activities [nmol min^-1 (mg protein)^-1]: for *orf3* fusion pLC92B-A, AM1 6, MxbD 320, MxbM 90, MxcE 100, MxcQ 80; for *orf4* fusion pLC200G, AM1 10, MxbD 290, MxbM 120, MxcE 80, MxcQ 60. Authors concluded these loci are negatively controlled by the methanol-oxidation regulatory system; MxcE and MxcQ were among the regulatory methanol-oxidation mutants tested (pqac-00000006, pqac-00000008). | *Methylobacterium extorquens* AM1 and regulatory mutants (MxbD, MxbM, MxcE, MxcQ) | Primary genetic/promoter-fusion study | 1997 | Chistoserdova & Lidstrom, *Microbiology* (1997), DOI: https://doi.org/10.1099/00221287-143-5-1729 |
| Engineered methanol sensor demonstrates transferable sensing function from the MxcQ/MxcQE system | Study states that five genes—*mxbDM*, *mxcQE*, and *mxaB*—are responsible for transcription of methanol oxidation genes; *mxcQ* and *mxbD* are sensor kinases and *mxcE* and *mxbM* are response regulators. Researchers fused the *M. extorquens* AM1 MxcQ sensing region to the *E. coli* EnvZ transmitter domain (MxcQZ AM1). The resulting chimeric system produced maximum *ompC* transcription and GFP signal at 0.01% methanol after 8 h; both chimeric TCS constructs sensed methanol down to 0.01%. This supports functional methanol sensing associated with the native MxcQ/MxcQE regulatory framework, though it does not directly characterize native MxcE domains (pqac-00000001, pqac-00000004, pqac-00000005). | Heterologous *Escherichia coli* carrying chimeric components derived from *Methylobacterium extorquens* AM1 | Synthetic biology / heterologous functional assay | 2020 | Selvamani et al., *Microbiology and Biotechnology Letters* (2020), DOI: https://doi.org/10.4014/mbl.1908.08009 |
| Genomic review places methanol oxidation genes in multiple chromosomal clusters and highlights remaining regulatory gaps | Genomic review of AM1 reports methanol oxidation genes are distributed in three chromosomal locations; one 12.5-kb cluster contains 14 *mxa* genes (*mxaFJGIRSACKLDEHB*), all transcribed in the same direction. The review states that genome analysis had identified about 30 new methylotrophy genes and that only “a few regulatory genes” involved in C1 oxidation/assimilation remained unidentified at the time, providing pathway context for regulators such as MxcQE. This review is valuable for placing MxcE within the broader methanol-oxidation network, though it does not itself experimentally resolve MxcE function (pqac-00000009, pqac-00000010). | *Methylobacterium extorquens* AM1 | Genomic review/minireview | 2003 | Chistoserdova et al., *Journal of Bacteriology* (2003), DOI: https://doi.org/10.1128/JB.185.10.2980-2987.2003 |


*Table: This table compiles the most relevant evidence linking MxcE and the MxcQE two-component system to methanol oxidation regulation in Methylorubrum/Methylobacterium extorquens AM1. It integrates mechanistic, genetic, heterologous sensing, and genomic-context studies, with quantitative values where available.*