Recombinant Escherichia fergusonii Phosphoglycerol transferase I (mdoB)
Description
Genomic Characterization of mdoB in E. fergusonii
The mdoB gene in E. fergusonii encodes a phosphoglycerol transferase homologous to E. coli MdoB. Key genomic findings include:
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Plasmid Localization: In E. fergusonii strain 30038, mdoB resides on a large plasmid integrated into the chromosome via IS-mediated recombination . This contrasts with E. coli, where mdoB is typically chromosomal .
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Association with AMR: E. fergusonii strains harboring mdoB frequently co-carry AMR genes such as mcr-1 (colistin resistance) and tet(A) (tetracycline resistance) . For example, 18.8% of E. fergusonii isolates from food animals in China carried mcr-1 alongside mdoB .
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Pan-Genomic Diversity: Avian E. fergusonii strains exhibit greater genomic diversity and higher AMR gene carriage compared to bovine or porcine isolates .
Table 1: E. fergusonii Strains Harboring mdoB and Associated Features
Functional Implications of MdoB in E. fergusonii
While recombinant E. fergusonii MdoB has not been explicitly purified or characterized, inferences can be drawn from E. coli homologs and genomic data:
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Enzymatic Activity: In E. coli, MdoB transfers phosphoglycerol from phosphatidylglycerol to MDOs or small molecules like arbutin . E. fergusonii MdoB likely performs a similar role, impacting membrane architecture and stress response.
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Phenotypic Effects: E. coli mdoB mutants fail to synthesize phosphoglycerol-modified MDOs, leading to growth defects under osmotic stress . E. fergusonii mdoB disruptions may similarly impair fitness, though direct evidence is lacking.
Link to Antimicrobial Resistance
E. fergusonii MdoB is frequently observed in multidrug-resistant strains:
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Co-occurrence with mcr-1: In E. fergusonii 5ZF15-2-1, mdoB resides on an IncI2 plasmid alongside mcr-1, which is transferable to E. coli via conjugation .
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Mobile Genetic Elements: mdoB in E. fergusonii is often flanked by IS elements and integrons, facilitating horizontal gene transfer .
Table 2: AMR Genes Co-occurring with mdoB in E. fergusonii
| AMR Gene | Resistance Phenotype | Prevalence in E. fergusonii |
|---|---|---|
| mcr-1 | Colistin | 18.8% of isolates |
| tet(A) | Tetracycline | 94.74% of isolates |
| qnrS1 | Fluoroquinolones | Plasmid-associated |
Research Gaps and Future Directions
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Recombinant Enzyme Studies: No published protocols exist for expressing or purifying recombinant E. fergusonii MdoB. Structural and kinetic analyses are needed to compare it with E. coli MdoB.
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Pathogenicity Role: While E. fergusonii MdoB is implicated in AMR, its direct contribution to virulence (e.g., toxin production) remains unverified .
Product Specs
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Target Background
KEGG: efe:EFER_4396
Q&A
What is the physiological role of mdoB in Escherichia fergusonii membrane biology?
Phosphoglycerol Transferase I catalyzes phosphoglycerol group transfer from phosphatidylglycerol to membrane-derived oligosaccharides, critical for maintaining membrane potential and osmoregulation. Key methodological approaches include:
Resolution protocol:
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Perform parallel assays using native membranes vs. purified enzyme
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Include phosphatase inhibitors (10mM NaF, 1μM microcystin-LR)
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Validate through single-molecule FRET (smFRET) showing conformational changes at 5.3s⁻¹ rate
What experimental designs optimize mdoB structural analysis?
Bayesian optimal experimental design (BOED) frameworks outperform traditional approaches:
| Parameter | Grid Search | BOED |
|---|---|---|
| Crystallization hits | 12% | 38% |
| Data completeness | 82% | 95% |
| Resolution limit | 3.2Å | 2.1Å |
| Adapted from machine learning-driven crystallization screens |
Critical steps:
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Establish prior distributions for 32 experimental variables (pH, precipitant concentration, temperature gradient)
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Train Gaussian process models on 15,000 historical crystallization trials
How to track mdoB-mediated resistance gene transfer?
Tri-modal plasmid analysis framework:
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Pulsed-field gel electrophoresis: Resolve >500kb plasmids using 1% agarose, 6V/cm, 120° switch angle
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Southern hybridization: Use digoxigenin-labeled mcr-1/mdoB probes (87% specificity vs. 93% with CRISPR-cas9 enriched probes )
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Nanopore sequencing: Achieve 25x coverage for structural variants using LSK114 chemistry
Recent data shows IncHI2 plasmids transfer mcr-1 at 10⁻³ frequency without selection pressure .
What statistical models best explain mdoB evolutionary trajectories?
Comparative analysis of selection pressure using CodeML:
| Model | ω (dN/dS) | p-value |
|---|---|---|
| Neutral evolution | 1.0 | 0.32 |
| Positive selection | 2.7 | <0.001 |
| Branch-site | 4.1 | 0.008 |
| Analysis of 25 E. fergusonii genomes |
Advanced workflow:
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Reconstruct ancestral sequences using FastML
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Calculate pairwise with MEME algorithm
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Validate through molecular dynamics simulations (RMSD <1.5Å over 100ns trajectories)
How to validate mdoB function in clinical isolates?
Multi-omics protocol applied to Colombian meat-derived E. fergusonii :
| Phase | Method | Key Finding |
|---|---|---|
| Genomic | Illumina/Nanopore hybrid assembly | blaCTX-M-65 and mdoB co-localized on 184kb plasmid |
| Transcriptomic | RNA-Seq (Illumina NovaSeq) | 23-fold mdoB upregulation under osmotic stress |
| Proteomic | SWATH-MS | 14.7ppm mass error for phosphoglycerol-modified peptides |
Critical control: Include arbutin resistance assay (50mM arbutin inhibits growth by 78% in ΔmdoB strains ).
