Recombinant Brucella suis biovar 1 Putative peptide transport system permease protein BRA1092/BS1330_II1084 (BRA1092, BS1330_II1084)

How does BRA1092/BS1330_II1084 compare structurally and functionally to other characterized permeases in pathogenic bacteria?

BRA1092/BS1330_II1084 belongs to a class of membrane transport proteins commonly found in gram-negative bacteria. While specific comparative analysis data is limited in the provided search results, permease proteins generally share common structural features:

• Multiple transmembrane helices forming channel structures

• Substrate binding domains with varying specificity

• Conserved motifs associated with transport mechanism

The functional mechanisms likely involve:

• Energy-coupled transport (possibly ATP-dependent)

• Conformational changes facilitating substrate translocation

• Interaction with other components of transport systems

Research examining the specific role of this permease would benefit from comparative analysis with other bacterial transport systems, particularly those involved in nutrient acquisition during intracellular survival phases .

What expression systems and conditions optimize production of functional recombinant BRA1092/BS1330_II1084?

The production of functional recombinant BRA1092/BS1330_II1084 has been successfully demonstrated using E. coli expression systems. The following methodological approach is recommended:

Expression System:

• Host: E. coli (strains optimized for membrane protein expression such as C41/C43 derivatives)

• Vector: pET-based with N-terminal His-tag for purification

• Induction: IPTG-regulated expression under T7 promoter

Optimization Parameters:

• Temperature: Lower temperatures (16-20°C) during induction to reduce inclusion body formation

• Induction concentration: 0.1-0.5 mM IPTG typically optimal for membrane proteins

• Growth phase: Induction at mid-log phase (OD600 0.6-0.8)

• Media composition: Enriched media with proper aeration

Purification Strategy:

• Membrane fraction isolation through differential centrifugation

• Solubilization using mild detergents (DDM, LDAO)

• Immobilized metal affinity chromatography (IMAC) utilizing the His-tag

• Size exclusion chromatography for final purification

The published protocols indicate successful expression with N-terminal His-tagging, though the tag type may be determined during the production process to optimize protein functionality .

What are the critical considerations for preserving stability and activity of purified BRA1092/BS1330_II1084?

Maintaining the stability and functional integrity of purified BRA1092/BS1330_II1084 requires careful attention to storage conditions and handling protocols:

Storage Recommendations:

• Primary storage: -20°C/-80°C for long-term preservation

• Working aliquots: 4°C for up to one week

• Avoid repeated freeze-thaw cycles (significantly reduces protein activity)

Buffer Composition:

• Tris/PBS-based buffer system

• Inclusion of 50% glycerol as a cryoprotectant

• pH maintained at 8.0 for optimal stability

• Consider addition of 6% trehalose as a stabilizing agent

Reconstitution Protocol:

• Briefly centrifuge vial before opening to collect contents

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

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

• Prepare small working aliquots to minimize freeze-thaw cycles

Activity Preservation:

• For functional assays, maintain protein in detergent micelles or reconstitute into proteoliposomes

• Consider addition of specific lipids that may be required for functional activity

• Monitor protein aggregation through dynamic light scattering before experimental use

What methodologies are most effective for characterizing the transport activity of BRA1092/BS1330_II1084?

Characterizing the transport activity of BRA1092/BS1330_II1084 requires multiple complementary approaches:

In Vitro Transport Assays:

• Liposome Reconstitution Method:

  • Purify recombinant protein using affinity chromatography

  • Reconstitute into proteoliposomes with controlled lipid composition

  • Establish concentration gradient of potential peptide substrates

  • Measure substrate accumulation using radioactive or fluorescently labeled peptides

• Electrophysiological Measurements:

  • Reconstitute protein into planar lipid bilayers

  • Record current changes upon addition of potential substrates

  • Characterize transport kinetics and substrate specificity

Substrate Binding Analysis:

• Isothermal titration calorimetry (ITC) to measure binding affinities

• Surface plasmon resonance (SPR) for real-time binding analysis

• Fluorescence-based binding assays using intrinsic tryptophan fluorescence

Functional Complementation:

• Express BRA1092/BS1330_II1084 in bacterial strains deficient in peptide transport

• Assess restoration of growth on peptide-containing media

• Compare transport efficiency with known peptide transporters

These approaches should be adapted based on hypothesized substrates derived from bioinformatic analysis of the permease family to which BRA1092/BS1330_II1084 belongs .

How can researchers determine the substrate specificity of BRA1092/BS1330_II1084?

Determining substrate specificity requires systematic evaluation of potential transport substrates through multiple experimental approaches:

Computational Prediction:

• Sequence alignment with characterized permeases of known specificity

• Structural modeling to identify potential substrate binding pockets

• Docking simulations with candidate peptide substrates

High-Throughput Screening:

• Competitive Binding Assays:

  • Use a known substrate with measurable properties (fluorescence/radioactivity)

  • Test displacement by libraries of potential substrates

  • Quantify relative binding affinities

• Transport Competition Assays:

  • Measure transport of a reporter substrate

  • Test inhibition by potential competing substrates

Genetic Approaches:

• Growth-based Selection:

  • Construct reporter strains where growth depends on specific substrate transport

  • Screen for conditions where BRA1092/BS1330_II1084 enables growth

• Directed Mutagenesis:

  • Modify predicted substrate binding residues

  • Assess changes in transport specificity and efficiency

Direct Measurement:

• Mass spectrometry to identify accumulated substrates in proteoliposomes

• Nuclear magnetic resonance (NMR) for direct observation of substrate interactions

A methodical combination of these approaches can establish the substrate profile and physiological relevance of this putative peptide transport system permease .

What is the contribution of BRA1092/BS1330_II1084 to Brucella suis intracellular survival?

The contribution of BRA1092/BS1330_II1084 to Brucella suis intracellular survival must be considered within the broader context of Brucella pathogenesis:

Physiological Context:
Brucella suis is a facultative intracellular pathogen that infects and multiplies within professional and nonprofessional phagocytes. After invasion, it blocks phagosome-lysosome fusion and replicates within a specialized membrane-bound compartment .

Potential Roles of BRA1092/BS1330_II1084:

• Nutrient Acquisition:

  • As a putative peptide transporter, it may facilitate uptake of amino acids or peptides from the host cell

  • Critical for bacterial survival in nutrient-limited intracellular environments

• Immune Evasion:

  • May contribute to modification of the bacterial surface composition

  • Potentially involved in transporting factors that interfere with host defense mechanisms

• Stress Response:

  • Could facilitate adaptation to intracellular stressors through transport of protective compounds

  • May function in maintaining membrane integrity under stress conditions

Experimental Evidence:
While the search results don't provide direct evidence specific to BRA1092/BS1330_II1084, transport systems have been identified as critical virulence factors in other intracellular pathogens. Signature-tagged transposon mutagenesis studies have identified various genes essential for Brucella intracellular survival, including membrane transporters .

What experimental systems best model the function of BRA1092/BS1330_II1084 during host-pathogen interactions?

To effectively study BRA1092/BS1330_II1084's role in host-pathogen interactions, researchers should consider the following experimental systems:

In Vitro Cellular Models:

• Human Macrophage Infection Model:

  • THP-1 or primary human macrophages

  • Comparative infection with wild-type vs. BRA1092/BS1330_II1084 mutant strains

  • Assessment of intracellular survival and replication kinetics

  • Analysis of phagosomal trafficking and maturation

• Non-phagocytic Cell Infection:

  • HeLa or epithelial cell models

  • Evaluation of invasion efficiency and intracellular multiplication

  • Assessment of cellular response to infection

Genetic Manipulation Approaches:

• Targeted Gene Disruption:

  • Construction of a BRA1092/BS1330_II1084 deletion mutant

  • Complementation studies to confirm phenotype specificity

  • Site-directed mutagenesis of key residues to understand functional domains

• Signature-Tagged Mutagenesis (STM):

  • The search results indicate successful application of STM in identifying Brucella virulence factors

  • This approach allows screening of multiple mutants simultaneously in infection models

  • Can identify the relative importance of BRA1092/BS1330_II1084 compared to other factors

Molecular Analysis Methods:

• Transcriptional Profiling:

  • RNA-seq analysis of wild-type vs. mutant during infection

  • Identification of compensatory mechanisms activated in the absence of the permease

• Protein Interaction Studies:

  • Immunoprecipitation to identify interaction partners

  • Bacterial two-hybrid screens for protein-protein interactions

These experimental systems provide complementary approaches to elucidate the specific role of BRA1092/BS1330_II1084 in the complex process of host-pathogen interaction during Brucella infection .

How can structural biology approaches enhance understanding of BRA1092/BS1330_II1084 function?

Advanced structural biology techniques offer powerful insights into the molecular mechanisms of BRA1092/BS1330_II1084 function:

Protein Structure Determination:

• X-ray Crystallography:

  • Challenges:

    • Membrane protein crystallization requires specialized detergents and conditions

    • Stabilization of conformational states may require substrate analogs or inhibitors

  • Methodological approach:

    • Screen multiple detergents and lipidic cubic phase crystallization

    • Consider fusion protein approaches (e.g., T4 lysozyme fusion) to enhance crystallization

    • Co-crystallization with antibody fragments or nanobodies to stabilize structure

• Cryo-Electron Microscopy (Cryo-EM):

  • Advantages for membrane proteins:

    • No crystallization requirement

    • Visualization of different conformational states

  • Implementation strategy:

    • Reconstitution in nanodiscs or amphipols to maintain native-like environment

    • Single-particle analysis to determine 3D structure

    • Classification algorithms to identify conformational heterogeneity

• Nuclear Magnetic Resonance (NMR):

  • Best for:

    • Dynamic studies of substrate binding

    • Conformational changes during transport cycle

  • Approach:

    • Selective isotopic labeling of key residues

    • Solution NMR for soluble domains

    • Solid-state NMR for transmembrane regions in lipid environments

Structure-Function Analysis:

• Molecular Dynamics Simulations:

  • Integration of structural data into molecular models

  • Simulation of protein dynamics in membrane environment

  • Prediction of substrate translocation pathways and energy barriers

• Structure-Guided Mutagenesis:

  • Identification of critical residues for substrate binding and transport

  • Design of mutants with altered specificity or transport properties

  • Validation through functional assays

The structural characterization would significantly advance understanding of substrate recognition, transport mechanism, and potential for targeted inhibition in the context of Brucella pathogenesis .

What are the methodological considerations for studying BRA1092/BS1330_II1084 interactions with the host immune system?

Understanding the interactions between BRA1092/BS1330_II1084 and the host immune system requires sophisticated experimental approaches:

Antigen Presentation Studies:

• Peptide Mapping:

  • Identify immunogenic epitopes within BRA1092/BS1330_II1084

  • Method:

    • Synthesize overlapping peptides spanning the protein sequence

    • Screen for T-cell reactivity using peripheral blood mononuclear cells (PBMCs) from infected hosts

    • Determine MHC restriction of immunodominant epitopes

• Antigen Processing Analysis:

  • Investigate how BRA1092/BS1330_II1084 is processed in antigen-presenting cells

  • Approach:

    • Pulse-chase experiments with labeled protein

    • Isolation and characterization of processed peptides

    • Analysis of processing pathway (proteasomal vs. endosomal)

Innate Immune Recognition:

• Pattern Recognition Receptor (PRR) Activation:

  • Determine if BRA1092/BS1330_II1084 activates or modulates PRRs

  • Methods:

    • Reporter cell lines expressing individual PRRs

    • Measurement of cytokine production in primary immune cells

    • Comparison of responses to wild-type vs. mutant proteins

• Inflammasome Activation Studies:

  • Assess potential role in inflammasome regulation

  • Approach:

    • Measure IL-1β and caspase-1 activation in macrophages

    • Compare responses between wild-type bacteria and transposon mutants

    • Reconstitution experiments with purified protein

Host-Pathogen Protein Interactions:

• Pull-down Assays and Mass Spectrometry:

  • Identify host proteins that interact with BRA1092/BS1330_II1084

  • Protocol:

    • Expression of tagged recombinant protein

    • Incubation with host cell lysates

    • Affinity purification and mass spectrometry identification

    • Validation through co-immunoprecipitation and co-localization

• Proximity Labeling Approaches:

  • Map spatial relationships during infection

  • Method:

    • Express BRA1092/BS1330_II1084 fused to proximity labeling enzymes (BioID, APEX)

    • Infection of host cells and activation of labeling

    • Purification and identification of labeled proteins

These methodological approaches provide a framework for investigating potential immunomodulatory functions of BRA1092/BS1330_II1084 beyond its primary role as a transport protein .

How can transcriptomic and proteomic approaches be applied to understand BRA1092/BS1330_II1084 regulation and function?

Integrative omics approaches provide powerful tools for understanding the regulation and functional context of BRA1092/BS1330_II1084:

Transcriptomic Analysis:

• Differential Expression Studies:

  • Compare gene expression under different growth conditions:

    • Intracellular vs. extracellular environment

    • Nutrient limitation vs. rich media

    • Different stages of infection

  Condition	BRA1092 Expression	Co-regulated Genes	Regulatory Motifs
  Intracellular	[Relative level]	[Gene clusters]	[Identified sequences]
  Nutrient stress	[Relative level]	[Gene clusters]	[Identified sequences]
  Mid-log phase	[Relative level]	[Gene clusters]	[Identified sequences]

• Transcriptional Regulation Analysis:

  • Promoter mapping and characterization

  • Identification of transcription factor binding sites

  • ChIP-seq to identify regulatory proteins

Proteomic Approaches:

• Expression Profiling:

  • Quantitative proteomics to measure protein levels under different conditions

  • Correlation with transcriptomic data to identify post-transcriptional regulation

• Post-translational Modifications:

  • Phosphoproteomics to identify regulatory phosphorylation sites

  • Analysis of other modifications affecting protein function or localization

• Protein-Protein Interaction Networks:

  • Immunoprecipitation coupled with mass spectrometry

  • Bacterial two-hybrid screening

  • Protein complementation assays

Integrative Analysis Framework:

• Co-expression Network Analysis:

  • Identify genes/proteins with similar expression patterns

  • Construct functional modules and pathways

  • Place BRA1092/BS1330_II1084 within its functional context

• Multi-omics Data Integration:

  • Correlate transcriptomic, proteomic, and phenotypic data

  • Develop predictive models of gene/protein function

  • Generate testable hypotheses about transport function and regulation

This integrative approach provides a systems-level understanding of BRA1092/BS1330_II1084 within the broader context of Brucella physiology and pathogenesis .

What bioinformatic approaches can predict functional partners of BRA1092/BS1330_II1084 in transport systems?

Predicting functional partners of BRA1092/BS1330_II1084 requires sophisticated bioinformatic approaches that leverage genomic context and evolutionary patterns:

Genomic Context Analysis:

• Operonic Structure Examination:

  • Identify genes co-located with BRA1092/BS1330_II1084

  • Analyze intergenic regions for regulatory elements

  • Compare operonic organization across Brucella species and strains

• Comparative Genomics:

  • Analyze gene neighborhood conservation across bacterial species

  • Identify syntenic regions containing putative transport system components

  • Compare with known peptide transport systems in related bacteria

Network-Based Predictions:

• Co-expression Network Analysis:

  • Construct networks based on expression correlation across conditions

  • Identify genes consistently co-regulated with BRA1092/BS1330_II1084

  • Cluster analysis to define functional modules

• Protein-Protein Interaction Prediction:

  • Sequence-based interaction site prediction

  • Structural modeling of potential protein complexes

  • Docking simulations to assess physical compatibility

Evolutionary Analysis:

• Phylogenetic Profiling:

  • Compare presence/absence patterns of genes across species

  • Identify proteins with similar evolutionary histories

  • Correlation analysis to predict functional relationships

• Co-evolution Detection:

  • Identify coordinated amino acid changes between protein pairs

  • Mutual information analysis of sequence alignments

  • Prediction of physically interacting residues between proteins

Methodological Workflow:

• Initial identification of candidates through genomic context

• Refinement through evolutionary analysis

• Validation through co-expression data

• Structural modeling of predicted complexes

• Experimental validation of top predictions

This systematic bioinformatic approach generates testable hypotheses about the complete transport system architecture and can guide subsequent experimental investigations of BRA1092/BS1330_II1084 function .