Recombinant Salmonella schwarzengrund UPF0208 membrane protein YfbV (yfbV)

What is Recombinant Salmonella schwarzengrund UPF0208 membrane protein YfbV?

Recombinant Salmonella schwarzengrund UPF0208 membrane protein YfbV (yfbV) is a full-length bacterial membrane protein consisting of 151 amino acids that can be expressed in heterologous systems such as E. coli. The protein belongs to the UPF0208 family of membrane proteins, which are conserved across various bacterial species. This recombinant protein is typically produced with an N-terminal His tag to facilitate purification and detection in experimental settings. The protein is derived from Salmonella schwarzengrund, a gram-negative bacterium, and is expressed as a recombinant protein for research purposes including structural studies, functional characterization, and potential applications in vaccine development .

What are the structural characteristics of YfbV protein?

The YfbV protein possesses several key structural features that define its function and localization:

• Membrane association: YfbV is classified as a membrane protein, suggesting transmembrane domains that anchor it within the bacterial membrane.

• Structural homology: Based on computational modeling approaches similar to those used for related proteins, YfbV likely shares structural features with the E. coli YtfB protein, which has been analyzed using AlphaFold with a pLDDT (predicted Local Distance Difference Test) global score of 81.8, indicating a confident model prediction .

• Domain organization: By inference from homologous proteins, YfbV likely contains domains similar to those identified in YtfB, including potential glycan-binding regions and membrane-spanning segments .

• Potential LysM-like domains: Based on homology with related proteins, YfbV may contain structures similar to the LysM domains found in YtfB, which are involved in binding to polysaccharides found on bacterial, plant, and eukaryotic cell surfaces .

How is YfbV related to other proteins like YtfB?

YfbV from Salmonella schwarzengrund shares significant homology with the YtfB protein from Escherichia coli. This relationship provides valuable insights into potential functions:

• Evolutionary conservation: Phylogenetic analysis of YtfB (a YfbV homolog) shows that this protein family is primarily conserved within Enterobacteriaceae, with highest conservation among Escherichia and Shigella species. The sequence identity between homologs ranges from 23% to 100% .

• Functional implications: The E. coli YtfB protein has been identified as playing a role in cell division, with overexpression causing cell division inhibition resulting in filamentous cells. By inference, YfbV may have similar functions in Salmonella .

• Domain conservation: YtfB contains a LysM-like domain at the C-terminus and a transmembrane domain near the N-terminus. These structural features may be conserved in YfbV, suggesting similar binding capabilities and cellular localization .

• Virulence factor relationships: YtfB shares homology with OapA, a virulence factor in Haemophilus influenzae that is critical for adherence to epithelial cells. This suggests that YfbV may also have a role in bacterial adherence to host cells .

What are the recommended handling and storage conditions for recombinant YfbV protein?

Proper handling and storage of recombinant YfbV protein is critical for maintaining its structural integrity and biological activity:

Long-term storage:

• Store lyophilized protein at -20°C to -80°C upon receipt

• Aliquoting is necessary for multiple uses to avoid repeated freeze-thaw cycles

• For working aliquots, store at 4°C for up to one week

Reconstitution protocol:

• Briefly centrifuge the vial prior to opening to bring contents to the bottom

• Reconstitute in deionized sterile water to a concentration of 0.1-1.0 mg/mL

• Add 5-50% glycerol (final concentration) for long-term storage

• Default final concentration of glycerol recommended is 50%

• Aliquot and store at -20°C to -80°C after reconstitution

Handling precautions:

• Avoid repeated freeze-thaw cycles as this can denature the protein

• The protein is intended for research use only, not for human consumption

• Always use aseptic technique when handling the protein solution

What is the function of YfbV in Salmonella schwarzengrund?

Based on its homology to YtfB in E. coli, YfbV likely plays a role in cell division processes. High expression levels of YtfB cause cell division inhibition, resulting in filamentous bacterial cells, suggesting a regulatory role in the division machinery . YfbV may function in a similar capacity in Salmonella.

The structural features of YfbV, inferred from homologous proteins, suggest potential roles in:

• Peptidoglycan interaction: Related proteins contain peptidoglycan binding domains, indicating YfbV may interact with the bacterial cell wall during cell division or other processes .

• Glycan binding: YtfB has been shown to bind to denuded glycans present in bacterial cell walls and specifically binds to N-acetylglucosamine and mannobiose glycans with high affinity. YfbV may possess similar binding specificities .

• Potential virulence function: Given the homology to adhesins like OapA from H. influenzae, YfbV may contribute to Salmonella's interaction with host cells, potentially playing a role in adhesion or colonization .

• Multi-functional nature: Like YtfB, YfbV may serve multiple functions depending on environmental conditions, potentially switching between roles in cell division and host-pathogen interactions .

How can recombinant Salmonella expressing YfbV be used in vaccine development?

While specific studies on YfbV-expressing Salmonella for vaccine development are not directly addressed in the search results, the principles of recombinant Salmonella vaccine vectors provide a framework for potential applications:

Vectoring strategies:

• Antigen expression location optimization: Recombinant Salmonella can be engineered to express proteins in different cellular compartments (cytoplasm, surface, periplasm), each with different immunogenic properties. For YfbV, expression on the bacterial surface or secretion to the periplasm might enhance immunogenicity, as demonstrated with other antigens .

• Chromosomal vs. plasmid-based expression: YfbV could be expressed from a plasmid or integrated into the Salmonella chromosome. A dual expression system could be developed where YfbV is expressed alongside other antigens, similar to systems expressing HIV-1 gp120 from a plasmid and HIV-1 Gag from the bacterial chromosome .

• Prime-boost strategies: Recombinant Salmonella expressing YfbV could be used in heterologous prime-boost vaccination strategies to enhance immune responses .

Potential immune responses:

• Mucosal and systemic immunity activation

• Induction of both humoral (antibody) and cellular (T-cell) responses

• Activation of innate immune mechanisms

Delivery approaches:

• Live attenuated Salmonella expressing YfbV

• Bacterial ghost (BG) delivery systems containing YfbV or YfbV-encoding DNA vaccines

• Combined delivery with adjuvants to enhance immune responses

What are the methodologies for expressing and purifying recombinant YfbV protein?

The expression and purification of recombinant YfbV protein requires specialized techniques for membrane proteins:

Expression system selection:

• E. coli expression: The most common system for YfbV expression, as demonstrated with the commercially available recombinant protein . Typical E. coli strains include BL21(DE3) or derivatives optimized for membrane protein expression.

• Expression vectors: Plasmids containing inducible promoters (T7, tac) with appropriate affinity tags (His-tag) facilitate controlled expression and subsequent purification.

Optimization strategies:

• Induction conditions: Temperature (typically lowered to 16-25°C), inducer concentration, and induction duration must be optimized to prevent inclusion body formation.

• Membrane protein solubilization: Extraction from membranes requires careful selection of detergents compatible with downstream applications.

Purification protocol:

• Cell lysis: Mechanical disruption (sonication, homogenization) in appropriate buffer systems containing protease inhibitors.

• Membrane fraction isolation: Ultracentrifugation to separate membrane fractions.

• Solubilization: Gentle detergent solubilization of membrane proteins.

• Affinity chromatography: His-tag purification using nickel or cobalt resins.

• Buffer exchange and concentration: Dialysis or size exclusion chromatography to remove detergents or exchange buffers.

• Quality control assessment: SDS-PAGE analysis and Western blotting to confirm purity (>90% as specified for commercial preparations) .

• Lyophilization: Final preparation as a lyophilized powder for stability and storage.

How does the structure of YfbV relate to its function?

The structure-function relationship of YfbV can be inferred from structural data of homologous proteins and computational predictions:

Key structural elements with functional implications:

• Transmembrane domains: The membrane localization of YfbV suggests transmembrane helical regions that anchor the protein within the bacterial membrane, positioning it to interact with both intracellular and extracellular components .

• LysM-like domains: By homology to YtfB, YfbV likely contains LysM-like domains which function in binding to polysaccharides. These domains are critical for interactions with glycans on bacterial cell walls and potentially on host cell surfaces .

• Model confidence regions: Computational structure models of related proteins (like YtfB in E. coli) show varying confidence scores (pLDDT) across different regions. Highly confident regions (pLDDT > 90) likely represent well-defined structural elements essential for function, while regions with lower confidence may represent flexible or disordered regions .

• Functional domains for cell division: The regions involved in cell division function may include interaction surfaces with other division proteins or peptidoglycan binding regions that help localize the protein to the division site .

• Glycan binding pockets: Specific structural features likely create binding pockets for N-acetylglucosamine and mannobiose glycans, as observed in homologous proteins .

The structure of YfbV likely represents an evolutionary adaptation that balances multiple functions - maintaining bacterial cell division processes while potentially facilitating host-pathogen interactions through specific binding interfaces .

What are the potential applications of YfbV in studying bacterial-host interactions?

YfbV offers several promising applications for studying bacterial-host interactions, particularly based on findings from homologous proteins:

Research applications:

• Adhesion studies: YfbV, like its homolog YtfB, may be involved in bacterial adhesion to specific host cells. Research models could be developed to study Salmonella schwarzengrund adherence to epithelial or other relevant host cells using YfbV mutants or recombinant strains with modified YfbV expression .

• Cell type specificity: YtfB has been shown to affect adherence to kidney cells but not bladder cells, suggesting tissue specificity. YfbV could be studied in the context of Salmonella's tissue tropism and specificity for different host cell types .

• Glycan-mediated interactions: The ability of related proteins to bind specific glycans (N-acetylglucosamine and mannobiose) with high affinity suggests YfbV could be used to study glycan-mediated host-pathogen interactions. Glycan arrays and binding assays could reveal host-specific glycan targets .

• Transition between motile and sessile lifestyles: Investigation of YfbV's role in the bacterial lifestyle switch from motile to sessile states within host environments could provide insights into bacterial adaptation mechanisms .

• Dual functionality models: YfbV could serve as a model for studying proteins with dual functions (cell division and host interaction), providing insights into how bacteria optimize their protein repertoire .

How does YfbV contribute to bacterial cell division or virulence?

YfbV's contribution to bacterial cell division and/or virulence can be analyzed based on functional studies of homologous proteins:

Cell division role:

• Division site localization: Like YtfB, YfbV may localize to the bacterial division site with some degree of glycan specificity, suggesting a role in coordinating cell wall synthesis with the division process .

• Division inhibition effects: High expression levels of YtfB cause cell division inhibition, resulting in filamentous cells. A similar phenotype might be observed with YfbV overexpression, suggesting a regulatory function in division timing or machinery assembly .

• Peptidoglycan interaction: The presence of domains that interact with cell wall components indicates a likely role in cell wall remodeling during division .

Virulence contributions:

• Adhesion to host cells: By homology to OapA from H. influenzae and YtfB from E. coli, YfbV may facilitate adhesion to specific host cell types, particularly in kidney tissue in the case of uropathogenic strains .

• Initial colonization steps: YfbV could be important in the initial stages of infection, helping bacteria adhere to host surfaces before establishing a more persistent infection .

• Immune evasion: Potential interactions with host glycans might contribute to immune evasion strategies or modulation of host immune responses .

• Environmental adaptation: The protein may play a role in adapting bacterial growth and division in response to the host environment, balancing between rapid proliferation and persistence .

What glycan binding properties does YfbV exhibit and how can they be studied?

Based on studies of homologous proteins, YfbV likely exhibits specific glycan binding properties that can be investigated through various methodologies:

Predicted binding properties:

• Target glycans: By homology to YtfB, YfbV likely binds to N-acetylglucosamine and mannobiose glycans with high affinity .

• Binding domain: The LysM-like domains found in related proteins are typically responsible for glycan binding, suggesting similar structural elements in YfbV mediate these interactions .

• Binding specificity: The specificity for certain glycans may reflect evolutionary adaptation to particular host environments or bacterial cell wall components .

Experimental approaches to study binding:

• Glycan array screening:

  • Recombinant YfbV can be tested against arrays of different glycans to determine binding specificity

  • Quantification of binding affinities through fluorescence-based detection

  • Comparative analysis with homologous proteins to identify conserved binding patterns

• Surface plasmon resonance (SPR):

  • Real-time binding kinetics measurement

  • Determination of association/dissociation constants

  • Assessment of binding stability under different conditions

• Isothermal titration calorimetry (ITC):

  • Thermodynamic characterization of binding interactions

  • Quantification of binding affinity, enthalpy, and stoichiometry

• Mutagenesis studies:

  • Identification of critical residues for glycan binding through targeted mutations

  • Structure-function correlations through binding studies with mutant proteins

• Crystallography with bound glycans:

  • Structural determination of YfbV-glycan complexes

  • Identification of binding pocket architecture and key interaction residues

What experimental approaches can be used to study YfbV localization in bacterial cells?

Understanding the subcellular localization of YfbV is crucial for elucidating its function. Several experimental approaches can be employed:

Fluorescence microscopy techniques:

• Fluorescent protein fusions:

  • Creation of YfbV-GFP (or other fluorescent protein) fusions

  • Live-cell imaging to track protein localization during different growth phases and division stages

  • Co-localization studies with other division proteins or cell wall markers

• Immunofluorescence microscopy:

  • Development of specific antibodies against YfbV

  • Fixed-cell imaging to visualize native protein distribution

  • Double-labeling with antibodies against other cellular components

Biochemical fractionation approaches:

• Membrane fractionation:

  • Separation of inner and outer membranes

  • Western blot analysis of fractions to determine membrane association

  • Detergent extraction profiles to characterize membrane integration

• Peptidoglycan binding assays:

  • Isolation of peptidoglycan sacculi

  • In vitro binding assays with purified YfbV

  • Competition assays with specific glycans or peptidoglycan fragments

Advanced imaging techniques:

• Super-resolution microscopy:

  • PALM/STORM imaging for nanoscale localization

  • Determination of YfbV clustering or organization patterns

  • Quantitative analysis of protein density at division sites

• Cryo-electron tomography:

  • Visualization of YfbV in the native cellular context

  • 3D reconstruction of protein arrangement relative to cell division machinery

  • Integration with computational modeling of division processes

How can recombinant YfbV be used in immunological studies?

Recombinant YfbV protein offers several applications in immunological research, particularly in the context of Salmonella infection and immunity:

Antibody development and serological studies:

• Polyclonal antibody production:

  • Immunization of research animals with purified recombinant YfbV

  • Development of antisera for detection of native YfbV in bacterial cells

  • Use in immunoblotting, immunoprecipitation, and immunohistochemistry

• Monoclonal antibody development:

  • Creation of hybridomas producing YfbV-specific antibodies

  • Epitope mapping to identify immunodominant regions

  • Development of diagnostic tools for Salmonella detection

T-cell response analysis:

• Epitope identification:

  • Screening of YfbV peptides for T-cell epitopes

  • Analysis of MHC presentation patterns

  • Characterization of T-cell receptor recognition

• Cell-mediated immunity assessment:

  • T-cell proliferation assays using YfbV stimulation

  • Cytokine profiling after YfbV exposure

  • Evaluation of memory T-cell responses in previously exposed subjects

Vaccine development applications:

• Adjuvant combinations:

  • Testing YfbV immunogenicity with different adjuvant formulations

  • Optimization of immune response quality and magnitude

  • Development of delivery systems for enhanced presentation

• Multi-antigen vaccine formulations:

  • Combination with other Salmonella antigens for broader protection

  • Assessment of antigenic competition or synergy

  • Evaluation in animal models of Salmonella infection

What are the current challenges in studying YfbV function?

Several significant challenges exist in fully characterizing YfbV function, which researchers should consider when designing experiments:

Technical challenges:

• Membrane protein expression and purification:

  • Difficulties in obtaining sufficient quantities of correctly folded protein

  • Maintaining native conformation during solubilization and purification

  • Selecting appropriate detergents that maintain function while allowing purification

• Functional reconstitution:

  • Challenges in reconstituting membrane proteins in artificial membrane systems

  • Ensuring proper orientation and oligomeric state

  • Validating that reconstituted protein retains native activity

Experimental design challenges:

• Redundancy and compensation:

  • Potential functional overlap with other bacterial proteins

  • Compensatory mechanisms that mask phenotypes in knockout studies

  • Need for conditional or inducible systems to study essential functions

• Multi-functionality:

  • Difficulty in separating different functional roles (cell division vs. adhesion)

  • Contextual function depending on growth conditions or infection stage

  • Designing experiments that can distinguish between different functions

Knowledge gaps:

• Structural information:

  • Limited availability of experimental structural data

  • Reliance on computational models and homology-based predictions

  • Need for high-resolution structures to guide functional studies

• Host-pathogen interaction complexity:

  • Variation in host glycan landscapes across tissues and species

  • Challenges in modeling complex host environments in vitro

  • Difficulty in translating in vitro findings to in vivo relevance