| Claim/Annotation | Evidence type (direct in AM1 vs inference from homologs) | Source (authors, year, journal) | Publication date (month/year if known) | Key quoted/parsed evidence | URL/DOI | Notes/limits |
|---|---|---|---|---|---|---|
| **mxaB (formerly moxB) is annotated as a transcriptional regulator in the primary methanol oxidation (MOX) gene cluster of *Methylorubrum extorquens* AM1** (pqac-00000002) | **Direct in AM1** (genome-based annotation/cluster context) | Chistoserdova, Chen, Lapidus, Lidstrom, 2003, *Journal of Bacteriology* (pqac-00000002) | 05/2003 | Parsed evidence: mxaB is listed as **“Transcriptional regulator”** (previous name **moxB**, accession **AF017434**) and placed in **cluster 1 (MOX)**; the paper states that most methanol oxidation genes are localized together in a large chromosomal operon/cluster (pqac-00000002). | https://doi.org/10.1128/JB.185.10.2980-2987.2003 ; DOI: 10.1128/JB.185.10.2980-2987.2003 | Strong for identity and pathway context, but this source does **not** define detailed mechanism, domain architecture, localization, or direct regulatory targets of MxaB. |
| **MxaB is required for activation of the mxa operon; the canonical mxa operon is mxaFJGIRSACKLDEHB, and this operon is downregulated during the lanthanide switch** (pqac-00000000) | **Direct in AM1** for operon activation/lanthanide-switch context, but from a **preprint** | Roszczenko-Jasińska et al., 2019, *bioRxiv* (pqac-00000000) | 05/2019 | Parsed evidence: the excerpt states that proteins “**are required for activation of the mxa operon (MxaB)**”; it explicitly lists the operon as **“mxaFJGIRSACKLDEHB”**; and indicates that during the lanthanide (Ln) switch, the **mxa operon is downregulated** while **xox1 operon genes are upregulated**. It also notes that in the absence of lanthanides, **MxaFI is the primary methanol dehydrogenase** (pqac-00000000). | https://doi.org/10.1101/647677 ; DOI: 10.1101/647677 | Useful functional statement connecting MxaB to mxa-operon activation in AM1, but because this is a preprint, conclusions should be weighed with that status; the excerpt does not provide MxaB domain architecture or a direct biochemical mechanism. |
| **MxaB is described as a LuxR-like orphan response regulator; homolog data suggest it may work with the membrane histidine kinase MxaY in lanthanide-dependent repression of mxaF and activation of xoxF** (pqac-00000001) | **Inference from homologs / comparative regulation**, not direct mechanistic proof in AM1 | Groom, Ford, Pesesky, Lidstrom, 2019, *Journal of Bacteriology* (pqac-00000001) | 08/2019 | Parsed evidence: the paper notes that in *M. extorquens* AM1, a homologous regulator is associated with the mxa cluster; in *Methylotuvimicrobium buryatense*, **MxaB is a “LuxR-like transcription factor”** / orphan response regulator required for **lanthanide-dependent repression of mxaF and activation of xoxF**. The study further states that **MxaY**, an integral membrane histidine kinase, is also required and that **MxaB and MxaY may form a nontraditional two-component system**, although it remains unresolved whether MxaB directly regulates xoxF/mxaF or how lanthanides affect MxaY (pqac-00000001). | https://doi.org/10.1128/JB.00120-19 ; DOI: 10.1128/JB.00120-19 | Important for domain/mechanistic inference and for aligning UniProt/InterPro domain predictions (receiver + LuxR-like DNA-binding output), but this row relies substantially on **homologous evidence outside AM1** rather than direct AM1 experiments on C5AQ96. |
| **The strong native PmxaF promoter, controlled within the methanol oxidation regulatory network that includes MxaB, is used as a benchmark in AM1 synthetic biology; new inducible promoters reached 6–36-fold induction and 9–166% of PmxaF output** (pqac-00000003, pqac-00000004) | **Direct in AM1** for application/tool performance; **indirect relevance** to MxaB because it uses the mxaF regulatory output as a benchmark rather than measuring MxaB directly | Carrillo et al., 2019, *ACS Synthetic Biology* (pqac-00000003, pqac-00000004) | 10/2019 | Parsed evidence: **PmxaF “drives 9% of soluble protein expression in M. extorquens”**; the new IPTG-inducible lacO promoters showed **“6 and 36-fold”** induction ranges; maximum strengths were **“9% and 166% of the strong PmxaF promoter”**; PL-derived promoters reached about **1.5-fold higher** mCherry levels than PmxaF; the authors position these tools for engineering *M. extorquens* as a C1-biotechnology chassis (pqac-00000003, pqac-00000004). | https://doi.org/10.1021/acssynbio.9b00220 ; DOI: 10.1021/acssynbio.9b00220 | This row supports **real-world implementation/application** of the methanol-oxidation regulatory output, but it does **not** directly test MxaB function. It is best interpreted as evidence that the **mxaF expression module** is a practically useful and quantitatively strong regulatory element in AM1. |


*Table: This table compiles the main direct and inferred evidence relevant to functional annotation of mxaB (UniProt C5AQ96) in Methylorubrum extorquens AM1, including pathway context, regulatory role, homolog-based mechanistic inference, and an application-focused row on the PmxaF output used in AM1 synthetic biology.*