Recombinant Brucella suis UPF0283 membrane protein BSUIS_A1077 (BSUIS_A1077)

What is BSUIS_A1077 and what is its significance in Brucella research?

BSUIS_A1077 (UniProt ID: B0CGI5) is a UPF0283 family membrane protein from Brucella suis, a gram-negative, aerobic pathogen that causes brucellosis. The protein consists of 357 amino acids and is encoded by the BSUIS_A1077 gene . The significance of this protein in Brucella research stems from its membrane localization, which may play roles in bacterial survival, pathogenicity, or host-pathogen interactions. Brucella suis is one of approximately 25 species in the Brucella genus and is closely related to Bartonella . As a membrane protein, BSUIS_A1077 could be involved in essential cellular functions such as transport, signal transduction, or maintenance of cell integrity, making it potentially valuable for understanding Brucella physiology and pathogenesis.

How does BSUIS_A1077 compare to similar proteins in other Brucella species?

BSUIS_A1077 belongs to the UPF0283 family of membrane proteins, which are found across various Brucella species. While specific comparative data for this protein across Brucella species is not directly provided in the search results, we can infer some relationships based on Brucella taxonomy. From a phylogenetic perspective, B. suis is closely related to other Brucella species like B. abortus, B. canis, B. ceti, B. melitensis, B. neotome, B. ovis, and B. pinnipedialis, which all represent the same species (B. melitensis) from a phylogenetic standpoint but have different host specificities . Therefore, UPF0283 membrane proteins in these species likely share high sequence homology with BSUIS_A1077, potentially with minor variations that might contribute to host adaptation. Comparative sequence analysis would be valuable for identifying conserved domains that may be essential for function versus variable regions that might contribute to species-specific properties.

What expression systems are optimal for producing recombinant BSUIS_A1077?

The optimal expression system for recombinant BSUIS_A1077 is Escherichia coli, as evidenced by successful expressions documented in the literature . E. coli offers several advantages for membrane protein expression, including rapid growth, high yield, and well-established protocols. For BSUIS_A1077 specifically, the protein has been successfully expressed with an N-terminal His-tag fusion in E. coli .

When designing an expression system for this membrane protein, researchers should consider:

• Vector selection: Vectors with inducible promoters (such as T7) allow controlled expression

• Fusion tags: N-terminal His-tags have proven successful and facilitate purification

• Host strain: BL21(DE3) or specialized membrane protein expression strains may improve yields

• Growth conditions: Lower temperatures (16-25°C) often improve membrane protein folding

• Inducer concentration: Titrating inducer levels helps optimize expression versus toxicity

Alternative expression systems such as cell-free systems or eukaryotic hosts might be considered for specialized applications requiring different post-translational modifications or folding environments.

What are the optimal conditions for purifying recombinant BSUIS_A1077?

Purification of recombinant BSUIS_A1077 requires specialized approaches due to its membrane protein nature. Based on available data, the following purification strategy is recommended:

• Extraction: Solubilize the membrane fraction using appropriate detergents that maintain protein structure and function. Mild detergents like n-dodecyl-β-D-maltoside (DDM) or n-octyl-β-D-glucopyranoside (OG) are often suitable.

• Affinity chromatography: For His-tagged BSUIS_A1077, nickel or cobalt affinity chromatography is effective. To distinguish full-length protein from truncated forms, consider:

  • Increasing imidazole concentration gradually during elution

  • Using vectors with fusion tags at both termini for full-length verification

• Buffer composition: Tris/PBS-based buffers with pH 8.0 have been successfully used . Addition of glycerol (6-50%) helps stabilize the protein.

• Storage: After purification, the protein can be lyophilized or stored in buffer with 50% glycerol at -20°C/-80°C .

• Quality control: SDS-PAGE analysis should confirm >90% purity .

For reconstitution of lyophilized protein, researchers should use deionized sterile water to achieve a concentration of 0.1-1.0 mg/mL and consider adding glycerol (final concentration 5-50%) for long-term storage .

What challenges are commonly encountered during BSUIS_A1077 expression and how can they be overcome?

Expression of full-length membrane proteins like BSUIS_A1077 presents several significant challenges:

To address hydrophobicity challenges specifically for BSUIS_A1077, researchers should analyze the protein sequence and secondary structure to identify hydrophobic regions that may cause folding issues . For translation initiation problems leading to truncated products, expression vectors with fusion tags on both N and C termini can help distinguish full-length proteins from truncated versions, particularly during purification by increasing the imidazole concentration at elution .

What is known about the function of BSUIS_A1077 in Brucella suis biology?

While the exact function of BSUIS_A1077 remains to be fully characterized, its classification as a UPF0283 membrane protein and structural features provide some insights. As a membrane protein in Brucella suis, BSUIS_A1077 likely contributes to one or more of the following functions:

• Membrane integrity and structure maintenance

• Transport of substances across the bacterial membrane

• Signal transduction or sensing of environmental conditions

• Potential roles in bacterial pathogenesis or host-pathogen interactions

Brucella suis is a zoonotic pathogen causing brucellosis, with particular relevance to swine infection but capable of infecting humans as well . The bacterium's ability to penetrate intact skin and its classification as a category B potential bioterrorism agent by NIAID highlight its significance . BSUIS_A1077, as a membrane protein, may contribute to the bacterium's survival mechanisms, host adaptation, or virulence.

Methodologically, to investigate BSUIS_A1077 function, researchers could employ a multi-faceted approach:

• Gene knockout or knockdown studies to assess phenotypic changes

• Protein-protein interaction studies to identify binding partners

• Localization studies using fluorescent tags or immunostaining

• Comparative genomics across Brucella species with different host specificities

How can recombinant BSUIS_A1077 be used in vaccine development research?

Recombinant BSUIS_A1077 presents several opportunities for vaccine development research against brucellosis, a significant zoonotic disease. As a membrane protein, BSUIS_A1077 may be exposed on the bacterial surface, making it potentially accessible to the host immune system and therefore a candidate antigen for vaccine development.

Methodological approaches for vaccine research using this protein include:

• Immunogenicity assessment: Evaluate the ability of purified recombinant BSUIS_A1077 to elicit humoral and cellular immune responses in animal models. This involves measuring antibody titers, T-cell responses, and cytokine profiles.

• Epitope mapping: Identify specific regions (epitopes) within BSUIS_A1077 that are recognized by the immune system. This can be accomplished through:

  • Peptide array analysis

  • Phage display technology

  • Computational prediction followed by experimental validation

• Subunit vaccine formulation: Incorporate full-length BSUIS_A1077 or immunogenic fragments into adjuvanted formulations for testing in appropriate animal models.

• Vector-based approaches: Express BSUIS_A1077 in viral or bacterial vectors for potential use as live attenuated vaccines.

• Protection studies: Challenge vaccinated animals with virulent Brucella suis to assess protective efficacy of BSUIS_A1077-based vaccine candidates.

While developing such vaccines, researchers must consider potential cross-reactivity with other bacterial species, stability of the recombinant protein, and appropriate delivery systems to ensure optimal immune responses.

What experimental approaches are suitable for studying protein-protein interactions involving BSUIS_A1077?

Understanding protein-protein interactions (PPIs) involving BSUIS_A1077 is crucial for elucidating its function in Brucella suis biology. Several experimental approaches are suitable for studying these interactions:

• Co-immunoprecipitation (Co-IP):

  • Express His-tagged BSUIS_A1077 in Brucella suis or recombinant systems

  • Solubilize membrane fractions with appropriate detergents

  • Perform pull-down assays using anti-His antibodies

  • Identify co-precipitated proteins by mass spectrometry

• Bacterial two-hybrid systems:

  • Adapt membrane-specific two-hybrid systems like BACTH (Bacterial Adenylate Cyclase Two-Hybrid)

  • Clone BSUIS_A1077 into appropriate vectors

  • Screen for interactions with libraries of Brucella proteins

• Cross-linking approaches:

  • Utilize membrane-permeable cross-linking agents

  • Analyze cross-linked complexes by mass spectrometry

  • Verify interactions with targeted approaches

• Surface Plasmon Resonance (SPR):

  • Immobilize purified BSUIS_A1077 on sensor chips

  • Flow potential binding partners over the surface

  • Measure binding kinetics and affinities

• Microscopy-based techniques:

  • Fluorescence Resonance Energy Transfer (FRET)

  • Bimolecular Fluorescence Complementation (BiFC)

  • Super-resolution microscopy for co-localization studies

When designing these experiments, researchers should account for the membrane environment required for proper BSUIS_A1077 folding, potentially incorporating nanodiscs, liposomes, or detergent micelles to maintain native-like membrane conditions.

What biosafety considerations are important when working with recombinant BSUIS_A1077?

When working with recombinant BSUIS_A1077, researchers must consider several important biosafety aspects, particularly given that this protein originates from Brucella suis, a zoonotic pathogen. While the recombinant protein itself (expressed in E. coli) does not pose the same risk as live Brucella, proper precautions remain essential:

• Biosafety level considerations:

  • Work with recombinant BSUIS_A1077 protein should typically be conducted in at least BSL-2 facilities

  • If there is any possibility of aerosolization, additional precautions may be warranted

  • Note that Brucella suis is classified as a potential bioterrorism agent (category B according to NIAID)

• Personal protective equipment (PPE):

  • Gloves, lab coat, and eye protection are mandatory

  • Consider respiratory protection when handling lyophilized protein to prevent inhalation

• Handling precautions:

  • Avoid generating aerosols during reconstitution or handling

  • Perform all manipulations in certified biosafety cabinets when possible

  • Be aware that Brucella suis can penetrate intact skin , so handle with appropriate caution

• Waste management:

  • Decontaminate all materials that contact the protein

  • Autoclave or chemically treat waste before disposal

  • Follow institutional guidelines for biohazardous waste disposal

• Emergency procedures:

  • Develop clear protocols for spills or exposures

  • Document any potential exposures and seek medical attention if necessary

Always consult with your institutional biosafety committee for specific guidelines applicable to your research context.

What are the optimal storage conditions to maintain BSUIS_A1077 stability and activity?

Maintaining the stability and activity of recombinant BSUIS_A1077 requires careful attention to storage conditions, particularly given its nature as a membrane protein. Based on available information, the following storage guidelines are recommended:

• Short-term storage (up to one week):

  • Store working aliquots at 4°C

  • Maintain in appropriate buffer systems (e.g., Tris/PBS-based buffer, pH 8.0)

• Long-term storage:

  • Store at -20°C or preferably -80°C

  • Add cryoprotectants such as glycerol (6-50%)

  • Aliquot to avoid repeated freeze-thaw cycles

• Lyophilized form:

  • Store lyophilized powder at -20°C/-80°C

  • Ensure containers are sealed to prevent moisture absorption

  • For reconstitution, briefly centrifuge vials before opening

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

• Buffer composition considerations:

  • Tris/PBS-based buffer, pH 8.0, with 6% Trehalose has been successfully used

  • For reconstituted protein, consider adding glycerol to 5-50% final concentration

• Stability indicators:

  • Monitor protein integrity by SDS-PAGE periodically

  • Assess functional activity using appropriate assays

  • Watch for signs of degradation or aggregation

Repeated freeze-thaw cycles should be strictly avoided as they can lead to protein denaturation and loss of activity . When designing experiments, plan ahead to minimize the need for multiple freeze-thaw events.

How can structural studies of BSUIS_A1077 be approached, given the challenges of membrane protein crystallography?

Structural characterization of membrane proteins like BSUIS_A1077 presents unique challenges but can be approached through multiple complementary techniques:

• X-ray crystallography:

  • Optimize protein purification to achieve high homogeneity and stability

  • Screen various detergents to identify those that maintain native structure while allowing crystal contacts

  • Employ lipidic cubic phase (LCP) or bicelle crystallization methods specifically designed for membrane proteins

  • Consider fusion partners (e.g., T4 lysozyme) to increase soluble domains for crystal contacts

• Cryo-electron microscopy (cryo-EM):

  • Particularly valuable for membrane proteins resistant to crystallization

  • Prepare protein in detergent micelles, nanodiscs, or amphipols

  • Use single-particle analysis for structure determination

  • Consider 2D crystallization in lipid bilayers for electron crystallography

• Nuclear Magnetic Resonance (NMR) spectroscopy:

  • Isotopically label the protein (13C, 15N) during expression

  • Optimize sample conditions (detergents, temperature, pH)

  • Consider solid-state NMR for proteins in lipid bilayers

• Computational approaches:

  • Use AlphaFold2 or similar AI-based tools for structural prediction

  • Validate predictions with experimental data from limited proteolysis, cross-linking, or spectroscopic techniques

• Hybrid approaches:

  • Combine low-resolution data from techniques like small-angle X-ray scattering (SAXS) with computational modeling

  • Use distance constraints from techniques like FRET or crosslinking to refine models

Each approach requires careful optimization of protein preparation, particularly regarding detergent selection to maintain native-like folding while accommodating the requirements of the structural technique.

What approaches can be used to study the potential role of BSUIS_A1077 in Brucella pathogenesis?

Investigating the potential role of BSUIS_A1077 in Brucella pathogenesis requires sophisticated experimental approaches that bridge molecular biology, cell biology, and infection models:

• Gene knockout and complementation studies:

  • Generate BSUIS_A1077 deletion mutants in Brucella suis

  • Complement with wild-type or site-directed mutant versions

  • Assess effects on bacterial survival, replication, and virulence

  • Evaluate in cellular infection models (macrophages, trophoblasts)

• Transcriptomic and proteomic analysis:

  • Compare wild-type vs. BSUIS_A1077 mutant strains under various conditions

  • Identify differentially expressed genes/proteins in response to host environments

  • Use RNA-seq and mass spectrometry-based proteomics

  • Integrate data to identify affected pathways

• Host-pathogen interaction studies:

  • Assess effects of BSUIS_A1077 on host cell entry, intracellular trafficking, and replication

  • Investigate interactions with host cellular components

  • Evaluate impact on host immune responses, including cytokine production and inflammasome activation

  • Use fluorescence microscopy to track bacterial localization

• In vivo infection models:

  • Compare wild-type and mutant strains in appropriate animal models (mice, guinea pigs)

  • Assess bacterial loads in target tissues

  • Evaluate pathological changes and immune responses

  • Consider competitive infection assays to directly compare fitness

• Post-translational modification analysis:

  • Investigate if BSUIS_A1077 undergoes modifications during infection

  • Assess how modifications might affect protein function and localization

  • Use phosphoproteomics or other targeted approaches

How can advanced proteomics techniques be applied to study BSUIS_A1077 expression and modifications in different conditions?

Advanced proteomics techniques offer powerful approaches to study BSUIS_A1077 expression, localization, and modifications under various environmental conditions or during infection:

• Quantitative proteomics:

  • SILAC (Stable Isotope Labeling with Amino acids in Cell culture) for metabolic labeling

  • TMT (Tandem Mass Tag) or iTRAQ (isobaric Tags for Relative and Absolute Quantitation) for chemical labeling

  • Label-free quantification approaches

  • Target: Measure changes in BSUIS_A1077 abundance across different conditions

• Post-translational modification (PTM) analysis:

  • Phosphoproteomics to identify phosphorylation sites

  • Glycoproteomics to identify glycosylation patterns

  • Redox proteomics to assess oxidative modifications

  • Enrichment strategies specific to the modification of interest

• Protein-protein interaction proteomics:

  • AP-MS (Affinity Purification-Mass Spectrometry)

  • BioID or APEX proximity labeling to identify neighbors in the membrane

  • Cross-linking Mass Spectrometry (XL-MS) to map interaction interfaces

  • Target: Identify BSUIS_A1077 interaction partners during infection

• Spatial proteomics:

  • Subfractionation of bacterial membranes followed by proteomics

  • LOPIT (Localization of Organelle Proteins by Isotope Tagging)

  • In situ labeling techniques combined with microscopy

  • Target: Determine precise localization within membrane subdomains

• Targeted proteomics:

  • SRM/MRM (Selected/Multiple Reaction Monitoring)

  • PRM (Parallel Reaction Monitoring)

  • Target: Detect and quantify BSUIS_A1077 with high sensitivity and specificity

Experimental design should include:

These advanced approaches require careful sample preparation due to the membrane nature of BSUIS_A1077, potentially using specialized enrichment or solubilization strategies.

How can researchers overcome solubility issues when working with recombinant BSUIS_A1077?

Membrane proteins like BSUIS_A1077 frequently present solubility challenges during expression, purification, and experimental handling. Researchers can implement the following strategies to address these issues:

• Optimization of extraction conditions:

  • Screen multiple detergents (DDM, LDAO, OG, CHAPS) at various concentrations

  • Test different detergent:protein ratios

  • Consider mixed detergent systems for improved extraction

  • Evaluate solubilization time and temperature

• Buffer optimization:

  • Vary pH conditions (typically pH 7.0-8.5 for membrane proteins)

  • Test different salt concentrations (150-500 mM)

  • Add stabilizing agents such as glycerol (5-20%)

  • Consider adding specific lipids that might stabilize the protein

• Alternative solubilization approaches:

  • Amphipols (e.g., A8-35) as detergent alternatives

  • Nanodiscs with membrane scaffold proteins (MSPs)

  • Styrene-maleic acid lipid particles (SMALPs)

  • Peptide-based nanodiscs (e.g., peptidiscs)

• Fusion protein strategies:

  • Express with solubility-enhancing fusion partners (MBP, SUMO, thioredoxin)

  • Consider truncation constructs if specific domains show better solubility

  • Design constructs with flexible linkers between domains

• Co-expression approaches:

  • Express with chaperones to assist proper folding

  • Co-express with natural binding partners if known

For researchers facing persistent solubility issues, a methodical approach documenting conditions tested and results observed is essential for optimization. Keep in mind that conditions optimal for solubility may need to be balanced with those required for downstream applications such as functional assays or structural studies.

What strategies can help troubleshoot expression problems with recombinant BSUIS_A1077?

Expression problems with membrane proteins like BSUIS_A1077 are common but can be addressed through systematic troubleshooting:

• Optimizing expression constructs:

  • Codon optimization for the expression host

  • Testing different fusion tags (His, GST, MBP, SUMO)

  • Adjusting tag position (N-terminal vs. C-terminal)

  • Modifying vector elements (promoters, ribosome binding sites)

• Expression host selection:

  • Standard E. coli strains (BL21(DE3), Rosetta)

  • Specialized membrane protein expression strains (C41(DE3), C43(DE3))

  • Considers hosts with altered membrane compositions

  • Testing cell-free expression systems for toxic proteins

• Expression conditions optimization:

  • Temperature reduction (37°C → 30°C → 25°C → 18°C)

  • Inducer concentration titration

  • Media composition (LB, TB, M9, auto-induction)

  • Duration of expression (4h vs. overnight)

• Addressing toxicity issues:

  • Using tightly controlled inducible systems

  • Testing expression in the presence of ligands or stabilizers

  • Employing secretion strategies or periplasmic targeting

  • Consider fusion to toxicity-mitigating partners

• Detecting low expression levels:

  • Western blotting with tag-specific antibodies

  • Using highly sensitive detection methods (e.g., luciferase reporters)

  • Scaling up culture volumes to compensate for low yields

  • Optimizing cell lysis and extraction conditions

A detailed troubleshooting matrix can help track experiments and outcomes:

For difficult membrane proteins like BSUIS_A1077, it may be necessary to test multiple combinations of these variables to identify optimal expression conditions.

How might BSUIS_A1077 serve as a potential target for antimicrobial development?

BSUIS_A1077, as a membrane protein specific to Brucella suis, presents several characteristics that make it a potential target for antimicrobial development:

• Essentiality assessment:

  • Determine if BSUIS_A1077 is essential for bacterial viability through gene knockout studies

  • Assess growth defects in conditional mutants

  • Evaluate contribution to survival in host environments

  • Quantify impact on virulence and persistence

• Target validation approaches:

  • Confirm absence of close homologs in mammalian cells to minimize off-target effects

  • Assess conservation across Brucella species for broad-spectrum potential

  • Evaluate accessibility of the protein to small molecules

  • Identify functionally critical domains or residues

• Drug discovery strategies:

  • High-throughput screening of compound libraries against purified BSUIS_A1077

  • Structure-based drug design if structural data becomes available

  • Fragment-based approaches to identify initial chemical scaffolds

  • Peptidomimetic design targeting protein-protein interaction interfaces

• Functional assay development:

  • Design assays to measure specific functions (e.g., transport activity)

  • Develop binding assays to identify molecules that interact with BSUIS_A1077

  • Create cell-based assays to evaluate compound permeability and efficacy

• Resistance potential analysis:

  • Assess the likelihood of resistance development

  • Identify potential resistance mechanisms

  • Consider combination approaches to reduce resistance risk

Researchers pursuing BSUIS_A1077 as an antimicrobial target should prioritize understanding its exact function and essentiality, as membrane proteins involved in critical cellular processes often make excellent drug targets due to their accessibility from the extracellular environment.

What emerging technologies might advance our understanding of BSUIS_A1077 function and interactions?

Several cutting-edge technologies show promise for elucidating BSUIS_A1077 function and interactions:

• Advanced structural biology approaches:

  • Microcrystal electron diffraction (MicroED) for structural determination from nano-sized crystals

  • Single-particle cryo-EM with improved detectors and processing algorithms

  • Integrative structural biology combining multiple experimental data sources

  • AI-based structure prediction (AlphaFold2, RoseTTAFold) with experimental validation

• Advanced genetic manipulation:

  • CRISPR-Cas9 based genome editing in Brucella suis

  • CRISPRi for conditional knockdown without complete deletion

  • Base editing for precise point mutations

  • Transpositional mutagenesis with next-generation sequencing readout

• Single-molecule techniques:

  • Single-molecule FRET to study conformational changes

  • Optical tweezers or atomic force microscopy for studying mechanical properties

  • Single-molecule tracking in live cells to monitor dynamics

  • Nanopore recording for potential transport functions

• Advanced imaging:

  • Super-resolution microscopy (PALM/STORM, STED) for localization studies

  • Correlative light and electron microscopy (CLEM)

  • Cryo-electron tomography of Brucella in native cellular contexts

  • Expansion microscopy for improved resolution of membrane organization

• Systems biology approaches:

  • Multi-omics integration (genomics, transcriptomics, proteomics, metabolomics)

  • Network analysis to position BSUIS_A1077 in broader biological pathways

  • Machine learning for pattern recognition in large-scale datasets

  • Mathematical modeling of membrane protein functions

These technologies, especially when combined, could provide unprecedented insights into the structural dynamics, functional mechanisms, and biological roles of BSUIS_A1077 in Brucella suis biology and pathogenesis.

How can computational approaches be used to predict BSUIS_A1077 function and potential binding partners?

Computational approaches offer powerful tools for generating hypotheses about BSUIS_A1077 function that can guide experimental research:

• Sequence-based predictions:

  • Profile-based searches (PSI-BLAST, HMMer) to identify distant homologs

  • Conservation analysis across species to identify functional residues

  • Co-evolution analysis to predict interacting residues

  • Transmembrane topology prediction using specialized algorithms (TMHMM, Phobius)

• Structure-based computational methods:

  • Homology modeling based on structural templates

  • Ab initio structure prediction using programs like AlphaFold2

  • Molecular dynamics simulations in membrane environments

  • Virtual screening for potential ligands or inhibitors

  • Binding site prediction and characterization

• Network-based approaches:

  • Protein-protein interaction predictions based on:

    • Sequence co-evolution patterns

    • Gene neighborhood analysis across genomes

    • Co-expression data mining

    • Text mining of scientific literature

  • Integration with existing Brucella interactome data

• Function prediction methods:

  • Gene Ontology term prediction

  • Domain-based functional annotation

  • Pathway association through gene set enrichment analysis

  • Ligand binding site prediction and substrate specificity analysis

• Machine learning integration:

  • Feature extraction from multiple data sources

  • Classification algorithms to predict functional categories

  • Deep learning applications for complex pattern recognition

  • Transfer learning from better-characterized membrane proteins

A systematic computational workflow might include:

• Initial sequence analysis and annotation

• Structure prediction and refinement

• Functional site identification

• Interaction partner prediction

• Molecular dynamics in membrane environment

• Hypothesis generation for experimental validation

These computational predictions should be validated through targeted experimental approaches, creating an iterative cycle of prediction and validation to advance understanding of BSUIS_A1077 function.