| Identifier(s) | Organism/strain | Genomic context (mll cluster boundaries and neighboring functions) | Proposed molecular role (inferred from homology/domain rules mentioned in evidence) | Experimental evidence (what was manipulated/measured) | Quantitative results | Notes/limitations | Key source (with year, venue, DOI/URL) |
|---|---|---|---|---|---|---|---|
| **mllDE**; **META1p4134**; user-provided **UniProt C5B1I6** | *Methylorubrum extorquens* AM1 (also referred to in source as *Methylobacterium extorquens* AM1) | Part of the **methylolanthanin (mll) biosynthetic gene cluster** spanning **META1p4129–META1p4138**. The cluster includes nearby TonB-dependent uptake-related genes **META1p4129–4131** and biosynthetic genes **META1p4132–4138**; Figure 2a places **mllDE** within the core biosynthetic operon alongside **mllA, mllBC, mllF, mllG, mllH, mllJ**. Neighboring functions include TonB-dependent uptake components and DUF-containing proteins (**META1p4136 DUF2218; META1p4138 DUF4142**) (pqac-00000000, pqac-00000003, pqac-00000005, pqac-00000009) | **Not directly biochemically characterized at gene level.** By cluster homology, **mllA/mllBC/mllDE/mllF** are homologous to the **petrobactin asbABCDEF** locus, supporting assignment to an **NRPS-independent siderophore-like/lanthanophore biosynthetic module**. AntiSMASH-style rules for homologous loci required **IucA_IucC**, **AMP-binding**, **PP-binding (asbD)**, and **DUF6005 (asbE/PF19468)** signatures; these data support an inferred **carrier/PP-binding ACP-like role somewhere within the core mll biosynthetic machinery**, but the evidence snippets do **not** assign the PP-binding or DUF6005 motif specifically to **mllDE** alone (pqac-00000000, pqac-00000002, pqac-00000004, pqac-00000005) | Evidence is **cluster-level**, not gene-specific: researchers deleted the **mll locus** (in a **ΔmxaFΔmll** strain), overexpressed **mll biosynthetic genes** in trans (**pAZ1**), identified the product **methylolanthanin (MLL)** by UPLC-MS/MS and NMR, tested Ln-binding by MS, quantified intracellular Nd by ICP-MS, and tested rescue with exogenous purified MLL. No experiment in the snippets isolates **mllDE/META1p4134** alone (pqac-00000001, pqac-00000003, pqac-00000005, pqac-00000006, pqac-00000007) | The **mll locus** was among the most induced under poorly soluble lanthanide conditions, with **~32-fold average upregulation** on **Nd2O3** versus **NdCl3**. **Deletion** of mll caused a **~30% decrease** in Ln bioaccumulation and a **~1.8-fold decrease** in Nd accumulation under NdCl3 in one assay; **overexpression** increased Nd accumulation by **~3.5-fold**. Exogenous **50 nM** MLL increased maximal OD under **2 µM NdCl3**; growth with **Nd2O3** in an overexpression background was reported as **0.026 h^-1** versus **0.037 h^-1** for ΔmxaF on NdCl3 (pqac-00000001, pqac-00000004, pqac-00000005, pqac-00000007) | The symbol **mllDE** is mapped in the source to the AM1 mll cluster, but the available evidence does **not** provide a direct biochemical reaction, substrate specificity, localization, or domain assignment uniquely for **mllDE/C5B1I6**. Current support is therefore **indirect**, based on **cluster membership, homology, and pathway-level phenotypes** rather than purified-protein or knockout-complementation data for this single gene (pqac-00000000, pqac-00000002, pqac-00000005) | Zytnick et al. **2022**, **bioRxiv**, “Discovery and characterization of the first known biological lanthanide chelator,” DOI: **10.1101/2022.01.19.476857**, URL: **https://doi.org/10.1101/2022.01.19.476857** (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000003, pqac-00000004, pqac-00000005, pqac-00000006, pqac-00000007, pqac-00000009) |


*Table: This table compiles the currently gathered evidence specific to mllDE/META1p4134 in Methylorubrum extorquens AM1. It distinguishes direct evidence from cluster-level inference, which is important because mllDE itself has not yet been individually characterized in the retrieved sources.*