Recombinant Escherichia coli O45:K1 UPF0059 membrane protein yebN (yebN)
Description
Introduction to UPF0059 Membrane Protein yebN
The UPF0059 membrane protein yebN, now also recognized as mntP, is a transmembrane protein found in Escherichia coli O45:K1 (strain S88 / ExPEC). This protein belongs to a class of membrane proteins that function as transporters, facilitating the movement of ions and small molecules across cellular membranes . Like other membrane transporters, yebN plays a crucial role in maintaining cellular homeostasis and participates in various biological signaling pathways . Until recently, the protein was annotated as yebN, but research has revealed its specific function in manganese efflux, leading to its redesignation as mntP .
Membrane proteins like yebN are fundamental components of cellular physiology, serving as gatekeepers for cellular compartments. As noted by Nieng Yan, the Shirley M. Tilghman Professor at Princeton's Department of Molecular Biology, "Both these classes of membrane proteins are extremely important for our health. Defects in these proteins are also associated with many different diseases" . The study of yebN provides valuable insights into bacterial metal homeostasis mechanisms and potential targets for antimicrobial interventions.
Historical Context and Nomenclature
The identification and characterization of yebN emerged from comprehensive genomic analyses of E. coli strains. Initially classified as an unannotated membrane protein with unknown function (hence the UPF0059 designation - Uncharacterized Protein Family), subsequent research has elucidated its critical role in manganese transport . Genome-wide expression studies comparing wild-type and ΔmntR strains revealed that yebN (now mntP) is positively regulated by the manganese-dependent transcription factor MntR, placing it within the manganese homeostasis network of E. coli .
Protein Structure and Characteristics
The UPF0059 membrane protein yebN consists of 188 amino acids with a molecular structure adapted for its function as a transmembrane transporter. The protein's primary sequence reveals hydrophobic regions characteristic of membrane-spanning domains, allowing it to integrate into the bacterial cell membrane.
Molecular Properties
The yebN protein exhibits several characteristic properties that define its function and interaction within cellular environments. As a membrane protein, it possesses distinct hydrophobic regions that anchor it within the lipid bilayer. These regions form the structural basis for its function as an ion transporter, creating a conduit through which manganese ions can be expelled from the cell.
Functional Role in Manganese Homeostasis
One of the most significant discoveries regarding yebN is its role in manganese homeostasis. Research has revealed that yebN, now recognized as mntP, functions as a manganese efflux pump that is positively regulated by the manganese-dependent transcription factor MntR .
Regulation by MntR
Whole-genome expression analysis comparing wild-type and ΔmntR strains of E. coli has shown that yebN (mntP) is uniquely upregulated in response to manganese through MntR-mediated regulation . This stands in contrast to other MntR-regulated genes like mntH (encoding a manganese importer) and mntS (formerly rybA), which are repressed by manganese via MntR. The differential regulation suggests a coordinated system where manganese uptake systems are downregulated while efflux systems are upregulated in response to elevated manganese levels .
Physiological Impact of yebN Deletion
Experimental studies have demonstrated that deletion of the mntP gene leads to profound manganese sensitivity and elevated intracellular manganese levels . This finding confirms the protein's role as a manganese efflux pump essential for maintaining appropriate intracellular manganese concentrations. The phenotypic consequences of mntP deletion underscore the protein's significance in metal ion homeostasis and cellular protection against manganese toxicity.
Recombinant Production Methods
Recombinant yebN is typically produced in expression systems, with yeast being a common host for the production of this bacterial membrane protein . The recombinant protein may include various tags to facilitate purification and detection, though the specific tag type is often determined during the production process . Purification typically involves chromatographic techniques, with product purity exceeding 85% as assessed by SDS-PAGE .
Research Applications and Significance
The study of yebN/mntP has significant implications for understanding bacterial physiology, pathogenesis, and potential therapeutic interventions. As a membrane protein involved in metal homeostasis, yebN represents an important model for studying the structure and function of bacterial transporters.
Role in Bacterial Manganese Homeostasis
The discovery that yebN (mntP) functions as a manganese efflux pump has expanded our understanding of how bacteria regulate metal ion concentrations. Manganese is an essential micronutrient that serves as a cofactor for many enzymes but becomes toxic at high concentrations. The MntR regulon, which includes mntH (importer), mntS, and mntP (efflux pump), constitutes a sophisticated system for maintaining optimal manganese levels .
The coordinated regulation of these genes reflects the precision with which bacteria control metal ion homeostasis. When manganese levels are elevated, MntR represses the expression of the importer (mntH) and mntS while activating the expression of the efflux pump (mntP), effectively reducing intracellular manganese concentrations . This balanced system highlights the importance of yebN in bacterial survival and adaptation to varying environmental conditions.
Potential Biotechnological Applications
The research on membrane proteins like yebN has been facilitated by recent advances in structural biology techniques, particularly cryo-electron microscopy (cryo-EM) . These methodological improvements have enabled researchers to obtain higher-resolution images of membrane proteins, providing deeper insights into their structure and function.
Recent developments in protein solubilization techniques, such as the design of water-soluble RFdiffused amphipathic proteins (WRAPs) through deep learning approaches, may further enhance the study of membrane proteins like yebN . These innovative methods could potentially overcome the challenges associated with the production and structural characterization of membrane proteins, facilitating their use in biotechnological applications.
Product Specs
Note: We will prioritize shipping the format currently in stock. However, if you have a specific format requirement, please indicate it in your order notes, and we will fulfill your request.
Note: All protein shipments are standardly accompanied by blue ice packs. If you require dry ice for shipping, please notify us in advance, as additional fees will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. The shelf life of lyophilized form is 12 months at -20°C/-80°C.
Target Background
KEGG: ecz:ECS88_1873
Q&A
What is the relationship between E. coli O45 strains and virulence factors?
E. coli O45 strains have been identified in both clinical and environmental settings, with distinct serotypes showing different virulence potentials. E. coli O45:H2 strains contain the locus of enterocyte effacement (LEE) pathogenicity island, which is absent in E. coli O45:H16 strains. This genomic difference explains their varied virulence profiles . To investigate this relationship, researchers should employ whole-genome sequencing followed by comparative genomic analysis between different serotypes. The methodological approach should include:
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Isolation and characterization of strains from various sources
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Whole-genome sequencing using next-generation sequencing platforms
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Bioinformatic analysis focusing on virulence-associated genes
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Phylogenetic analysis to establish evolutionary relationships
E. coli O45:H2 strains show evolutionary proximity to E. coli O103:H2 strains, sharing high homology in virulence factors including Stx prophages, suggesting they may have comparable virulence potential .
How does YebN/YibN function in membrane protein biogenesis in E. coli?
YibN functions as a significant interactor of YidC, a known membrane insertase, and plays a role in enhancing the production and membrane insertion of YidC substrates. Research methodologies to study this function include:
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Proximity-dependent biotin labeling (BioID) to identify protein-protein interactions
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Affinity purification-mass spectrometry assays conducted on native membranes
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On-gel binding assays with purified proteins
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Co-expression studies and in vitro protein translation assays
These approaches have demonstrated that YibN enhances the production of various small membrane proteins, including M13 procoat (PC-Lep), Pf3 coat proteins (Pf3-23Lep), F0c subunit of ATP synthase, and SecG . The molecular evidence indicates that YibN forms a stable complex with YidC in detergent conditions, with this interaction dependent on YibN's transmembrane segment .
What is the structural composition of YebN/YibN protein?
YibN is a 16 kDa membrane protein composed of:
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An N-terminal transmembrane segment that anchors the protein to the membrane
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A cytosolic rhodanese-like domain that extends into the bacterial cytoplasm
The protein has a specific membrane orientation, with the bulk of the protein facing the cytosolic side of the inner membrane . Structural characterization requires techniques such as:
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X-ray crystallography or cryo-electron microscopy for high-resolution structures
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Membrane topology analysis using reporter fusion proteins
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Secondary structure prediction using bioinformatic tools
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Tertiary structure modeling based on homologous proteins with known structures
The transmembrane segment is particularly critical, as deletion of this region abolishes the association with YidC, suggesting that their interaction occurs primarily within the hydrophobic interior of the lipid bilayer .
How does the expression of YebN/YibN affect membrane lipid composition and organization?
Overproduction of YibN has been demonstrated to stimulate membrane lipid production and induce significant changes in membrane morphology. The methodological approach to investigate this effect includes:
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Thin-layer chromatography and mass spectrometry to analyze lipid composition
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Transmission electron microscopy to visualize membrane structures
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Fluorescent labeling of membrane components combined with confocal microscopy
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Lipidomic analysis to quantify changes in phospholipid species
Research has shown that YibN overexpression is associated with:
| Membrane Characteristic | Effect of YibN Overexpression | Detection Method |
|---|---|---|
| Lipid synthesis | Increased production | Lipid extraction and analysis |
| Membrane morphology | Proliferation, circumvolutions, multilayered structures | Transmission electron microscopy |
| Inner membrane structure | Significant reorganization | Electron microscopy |
| Outer membrane structure | Less affected | Comparative microscopy analysis |
These effects appear to be primarily localized to the inner membrane, with the outer membrane showing less structural alteration . This suggests that YibN may interfere with YidC lipid scramblase activity, potentially linking membrane protein insertion with lipid organization.
What is the relationship between YebN/YibN and YidC in the context of the SecYEG translocon?
The evidence suggests a complex interplay between YibN, YidC, and the SecYEG translocon in membrane protein biogenesis. Researchers investigating this relationship should employ:
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Genetic depletion or knockout studies to observe phenotypic effects
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Protein-protein interaction studies using pull-down assays and co-immunoprecipitation
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In vitro reconstitution experiments with purified components
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Site-directed mutagenesis to identify critical interaction residues
YibN has been found to enhance the production of SecG, a component of the SecYEG translocon, but this enhancement is abolished when SecG contains the I20E mutation in its transmembrane region . This suggests a specific interaction that depends on the transmembrane architecture of SecG. Furthermore, YibN is upregulated upon depletion of YidC or SecDF-YajC, indicating a potential compensatory mechanism in the membrane protein biogenesis pathway .
What genomic factors influence the expression and regulation of YebN/YibN in different E. coli strains?
The expression and regulation of YibN appears to be influenced by its genomic context and strain-specific factors. To investigate this area, researchers should consider:
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Comparative genomic analysis across multiple E. coli strains
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Transcriptomic profiling under various growth conditions
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Promoter activity assays using reporter gene fusions
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Chromatin immunoprecipitation to identify transcription factor binding
YibN gene (yibN) is located on the same operon as grxC, secB, and gpsA, which encode proteins with related physiological functions: GrxC promotes protein disulfide bond reduction, SecB maintains proteins competent for secretion, and GpsA is involved in glycerophospholipid synthesis . This genomic arrangement suggests coordinated expression and potential functional relationships between these proteins.
Interestingly, genome-wide studies have shown that YibN is upregulated under specific stress conditions, particularly during depletion of YidC or SecDF-YajC . This stress-responsive expression pattern provides insight into potential regulatory mechanisms and physiological roles.
How can YebN/YibN be utilized in enhancing recombinant protein production in E. coli expression systems?
Given YibN's ability to enhance membrane protein production, it presents potential applications in biotechnological contexts. Methodological approaches to explore this application include:
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Development of co-expression vectors containing YibN and target proteins
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Optimization of induction conditions for synchronized expression
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Quantitative assessment of membrane protein yield and quality
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Structural and functional characterization of the produced proteins
Research has demonstrated that YibN co-expression significantly increases the yield of various membrane proteins, including:
These results were obtained through both in vivo co-expression experiments and in vitro protein translation and insertion assays . The effect appears to be specific to certain membrane proteins, suggesting that YibN may interact with particular structural features or insertion pathways.
What are the optimal conditions for expressing and purifying recombinant YebN/YibN protein?
Recombinant expression and purification of membrane proteins like YibN presents unique challenges. The methodological approach should include:
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Selection of appropriate expression systems (E. coli strains optimized for membrane protein expression)
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Design of expression constructs with suitable affinity tags
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Optimization of induction parameters (temperature, inducer concentration, duration)
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Development of membrane extraction and protein solubilization protocols
Based on successful membrane protein purification strategies, researchers should consider:
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Using mild detergents for membrane solubilization (e.g., n-dodecyl-β-D-maltoside)
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Employing affinity chromatography followed by size exclusion chromatography
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Including stabilizing agents during purification to maintain native conformation
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Validating protein quality through functional assays and structural analysis
Special attention should be given to maintaining the native conformation of the transmembrane segment, as this region is critical for YibN's interaction with YidC and potentially other membrane proteins .
How can researchers effectively study the YebN/YibN-YidC interaction in vitro?
Investigating protein-protein interactions involving membrane proteins requires specialized techniques. The methodological approach should include:
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Detergent-based co-purification assays with affinity-tagged proteins
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Reconstitution of proteins into artificial membrane systems (liposomes, nanodiscs)
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Biophysical characterization using techniques such as surface plasmon resonance or isothermal titration calorimetry
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Structural studies using X-ray crystallography or cryo-electron microscopy
Successful on-gel binding assays have demonstrated that YidC and YibN form a stable complex in detergent conditions . This interaction depends on YibN's transmembrane segment, suggesting that the binding interface is located within the membrane region. To further characterize this interaction, researchers could employ site-directed mutagenesis to identify specific residues involved in complex formation.
How can researchers differentiate between direct and indirect effects of YebN/YibN expression on membrane protein biogenesis?
Distinguishing direct from indirect effects requires careful experimental design and data interpretation. The methodological approach should include:
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Time-course experiments to establish the sequence of events
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In vitro reconstitution studies with defined components
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Detailed kinetic analysis of membrane protein insertion
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Systematic mutagenesis to identify critical functional regions
Researchers have observed that YibN enhances the production of various membrane proteins, but the mechanism may involve direct protein-protein interactions, alterations in membrane properties, or a combination of both . The finding that YibN overexpression stimulates membrane lipid production and alters membrane morphology suggests that some effects might be indirect, mediated through changes in the lipid environment.
To differentiate between these possibilities, researchers might compare the effects of wild-type YibN with mutant variants lacking specific functional domains or interaction capabilities.
What bioinformatic approaches are most effective for identifying YebN/YibN homologs across bacterial species?
Identifying homologs across species requires sophisticated bioinformatic analyses. The methodological approach should include:
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Sequence-based searches using tools like BLAST, PSI-BLAST, or HMMer
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Secondary structure prediction and profile-based searches
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Genome context analysis to identify conserved genomic neighborhoods
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Phylogenetic analysis to establish evolutionary relationships
Effective search strategies might include:
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Using both sequence and structural features as search criteria
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Examining conservation of the transmembrane segment and rhodanese-like domain
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Analyzing genomic context for conservation of the operon structure (grxC, secB, gpsA)
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Looking for proteins with similar expression patterns (e.g., upregulation in response to SecYEG stress)
This comprehensive approach would help identify both close homologs and more distantly related proteins with similar functions across diverse bacterial species.
