Recombinant Burkholderia ambifaria UPF0060 membrane protein Bamb_1160 (Bamb_1160)

What is the structure and basic characteristics of Bamb_1160 protein?

Bamb_1160 is a UPF0060 family membrane protein from Burkholderia ambifaria with a full length of 110 amino acids. The protein has the following characteristics:

• Amino Acid Sequence: MTELMKIAALFAVTALAEIVGCYLPWLVLKGGRPVWLLVPAALSLALFAWLLTLHPSAAGRTYAAYGGVYIAVALIWLRVVDGVALTRWDAAGAVLALGGMAVIALQPRA

• Protein Family: UPF0060 membrane protein family

• UniProt ID: Q0BGK5

• Source Organism: Burkholderia ambifaria (strain ATCC BAA-244 / AMMD)

• Gene Name: Bamb_1160

The protein is predicted to be a transmembrane protein based on its hydrophobic regions and membrane localization signals, though crystallographic data is not currently available in the literature for full structural determination .

What are the optimal storage conditions for recombinant Bamb_1160 protein?

For optimal stability and functionality, recombinant Bamb_1160 protein should be stored according to the following guidelines:

• Short-term storage: Working aliquots can be stored at 4°C for up to one week

• Long-term storage: Store at -20°C or -80°C

• Storage buffer: Typically stored in Tris/PBS-based buffer with 6% Trehalose, pH 8.0

• Important note: Repeated freeze-thaw cycles are not recommended as they can lead to protein degradation and loss of activity

For lyophilized preparations, reconstitution should be performed by briefly centrifuging the vial prior to opening, then reconstituting in deionized sterile water to a concentration of 0.1-1.0 mg/mL. Adding glycerol to a final concentration of 5-50% (typically 50%) is recommended before aliquoting for long-term storage .

How does Burkholderia ambifaria fit into the taxonomy of Burkholderia species?

Burkholderia ambifaria is a member of the Burkholderia cepacia complex (BCC), a group of closely related bacteria within the genus Burkholderia. The taxonomic position can be understood as follows:

The BCC contains several species including B. cepacia, B. multivorans, B. cenocepacia, B. vietnamiensis, and B. ambifaria among others . Originally identified from the rhizosphere of plants, B. ambifaria has been found to be less commonly associated with human infections compared to other BCC species like B. cenocepacia .

What experimental methods are most effective for expressing and purifying recombinant Bamb_1160?

Expression and purification of recombinant Bamb_1160 can be optimized using several methodological approaches:

Expression System Selection:

• E. coli: Most commonly used host for Bamb_1160 expression, with successful results reported using standard expression strains

• Mammalian cells: Alternative expression system that may provide different post-translational modifications, though typically with lower yields

Optimization Protocol:

• Vector design: Incorporate N-terminal His-tag for simplified purification, using vectors with strong promoters (T7 or tac)

• Expression conditions:

  • IPTG concentration: 0.1-1.0 mM

  • Temperature: Lower temperature (16-25°C) may improve membrane protein folding

  • Duration: 4-16 hours post-induction

• Cell lysis: Use detergent-based methods (e.g., n-dodecyl-β-D-maltoside) to solubilize membrane proteins

• Purification strategy:

  • IMAC (Immobilized Metal Affinity Chromatography) using Ni-NTA resin

  • Optional secondary purification: Size exclusion chromatography

Quality Control Assessment:

• SDS-PAGE: Verify purity >90%

• Western blot: Confirm identity using anti-His antibodies

• Mass spectrometry: Validate protein mass and integrity

For membrane proteins like Bamb_1160, introducing mild detergents during purification is crucial for maintaining protein stability and preventing aggregation while preserving native conformation.

How can researchers design detection assays for Burkholderia ambifaria in clinical or environmental samples?

Several molecular detection strategies have been developed for B. ambifaria and other BCC species, with particular emphasis on nucleic acid-based methods:

Recombinase-Aided Amplification (RAA) Assay:
The RAA assay targeting the 16S rRNA gene has shown excellent sensitivity and specificity for BCC detection, including B. ambifaria:

• Sensitivity: 10 copies/μL

• Specificity: 98.5%

• Detection time: ≤10 minutes at 39°C

• Cost efficiency: Approximately $5 per sample (compared to $45 for conventional PCR)

RAA Protocol Implementation:

• Design primers and probes targeting conserved regions of 16S rRNA gene

• Optimize primer-probe combinations for highest amplification efficiency

• Perform reaction at constant temperature (39°C) for 10 minutes

• Detect amplification using fluorescence monitoring

Critical considerations for assay validation:

• Test against multiple BCC species (B. cepacia, B. multivorans, B. vietnamiensis, and B. ambifaria)

• Include non-BCC Burkholderia species (e.g., B. gladioli) as specificity controls

• Validate with clinical samples from diverse sources

The RAA assay has demonstrated superior performance compared to conventional PCR, qPCR, and LAMP methods for BCC detection, making it particularly valuable for rapid clinical diagnostics .

What is known about the functional role of Bamb_1160 in Burkholderia ambifaria biology?

While specific functions of Bamb_1160 remain to be fully elucidated, analyses based on homology, genomic context, and preliminary studies suggest several potential roles:

Predicted Membrane Functions:

• Membrane integrity: As a UPF0060 family membrane protein, Bamb_1160 likely contributes to cell envelope structure and stability

• Transport: May participate in small molecule transport across the bacterial membrane, though specific substrates remain unidentified

• Signaling: Potential involvement in environmental sensing or signal transduction pathways

Genomic Context Insights:
Genomic analyses of B. ambifaria reveal that membrane proteins like Bamb_1160 exist within a complex network of functional elements, including:

• Specialized metabolite biosynthetic gene clusters (BGCs)

• Antimicrobial compound production systems

• Plant-microbe interaction mechanisms

Research Gaps and Opportunities:

• Functional knockout studies are needed to determine essentiality

• Interactome analysis could reveal protein-protein interaction partners

• Comparative analysis with homologs in other Burkholderia species may illuminate evolutionary conservation

Understanding Bamb_1160's function remains an open question that requires further investigation using techniques such as gene knockout, protein interaction studies, and localization experiments.

How can researchers leverage Burkholderia ambifaria's biological properties for agricultural applications?

B. ambifaria has significant potential for agricultural applications, particularly as a biocontrol agent and plant growth promoter:

Demonstrated Agricultural Applications:

• Biocontrol of Plant Pathogens:

  • B. ambifaria XN08 shows strong antagonistic activity against Rhizoctonia cerealis, the causal agent of wheat sharp eyespot disease

  • BCC0191 strain protects pea seedlings from oomycete damping-off disease

  • Produces antimicrobial compounds effective against fungal pathogens

• Plant Growth Promotion Activities:

  • Phosphate solubilization

  • Indole-3-acetic acid (IAA) production

  • Protease and siderophore production

Mechanism of Action Table:

Research Considerations:

• Despite its biocontrol potential, B. ambifaria was previously registered as a biopesticide (e.g., Blue Circle) but withdrawn due to potential human health risks

• Recent studies suggest strain BCC0191 did not cause disease in a murine respiratory infection model, renewing interest in its biopesticide applications

• Researchers should implement appropriate containment measures when working with BCC organisms

Effective utilization requires balancing agricultural benefits against potential risks, particularly for immunocompromised individuals .

What are the best approaches for investigating protein-protein interactions of Bamb_1160?

Investigating protein-protein interactions (PPIs) of Bamb_1160 requires specialized techniques suitable for membrane proteins:

Recommended PPI Investigation Methods:

• Membrane Yeast Two-Hybrid (MYTH) System:

  • Specifically designed for membrane proteins

  • Split-ubiquitin based detection system

  • Protocol optimization would include:

    • Ensuring proper membrane insertion

    • Screening against genomic or custom libraries

    • Validation of positive interactions with secondary assays

• Co-Immunoprecipitation with Crosslinking:

  • Chemical crosslinking preserves transient interactions

  • Anti-His antibodies can target recombinant His-tagged Bamb_1160

  • Mass spectrometry analysis of co-precipitated proteins

  • Detergent selection is critical for maintaining membrane protein solubility

• Proximity-Dependent Biotin Identification (BioID):

  • Fusion of biotin ligase to Bamb_1160

  • In vivo biotinylation of proximal proteins

  • Streptavidin-based purification followed by MS identification

  • Particularly useful for identifying weak or transient interactions

• Surface Plasmon Resonance (SPR):

  • For validating specific interactions with candidate proteins

  • Requires successful reconstitution in lipid nanodiscs or detergent micelles

  • Provides quantitative binding parameters (Kd, kon, koff)

Challenges and Solutions:

• Membrane protein solubility: Use appropriate detergents (DDM, CHAPS, or digitonin)

• Confirmation bias: Implement proper negative controls and statistical analysis

• Technical artifacts: Verify interactions using orthogonal techniques

These approaches can help uncover the interactome of Bamb_1160, potentially revealing its functional role in B. ambifaria biology.

How should researchers approach comparative genomics studies of Bamb_1160 homologs across Burkholderia species?

Comparative genomics of Bamb_1160 homologs can provide insights into evolutionary conservation, functional importance, and species-specific adaptations:

Methodological Framework:

• Homolog Identification:

  • Use BLAST/HMMER searches against Burkholderia genomes

  • Implement reciprocal best hit approach to identify true orthologs

  • Include distant homologs from related genera for broader evolutionary context

• Sequence Alignment and Analysis:

  • Multiple sequence alignment using MUSCLE or MAFFT algorithms

  • Conservation analysis to identify invariant residues (potential functional sites)

  • Detect selection signatures using dN/dS ratio analysis

  • Analyze transmembrane topology conservation using programs like TMHMM

• Phylogenetic Analysis:

  • Construct maximum likelihood or Bayesian phylogenetic trees

  • Compare gene tree with species tree to detect horizontal gene transfer events

  • Assess congruence between UPF0060 family evolution and Burkholderia speciation

• Genomic Context Analysis:

  • Analyze synteny of surrounding genes across species

  • Identify co-evolved gene clusters that may indicate functional relationships

  • Examine regulatory elements in promoter regions

Example Comparative Analysis Targets:

• B. cepacia complex members (BCC)

• Non-BCC Burkholderia species

• More distant relatives including Ralstonia and Pseudomonas species

Expected Outcomes:

• Identification of conserved functional motifs

• Detection of species-specific adaptations

• Insights into evolutionary history and potential functional divergence

• Correlation with ecological niches and pathogenicity patterns

This approach may reveal whether Bamb_1160 function is conserved across Burkholderia species or has undergone functional divergence in plant-associated versus pathogenic lineages.

What methodological considerations are important when studying the localization and membrane topology of Bamb_1160?

Understanding the localization and membrane topology of Bamb_1160 requires specialized techniques adapted for bacterial membrane proteins:

Experimental Approaches for Localization and Topology:

• GFP Fusion Protein Analysis:

  • C-terminal and N-terminal GFP fusions to determine membrane orientation

  • Microscopy to visualize subcellular localization

  • Flow cytometry for quantitative assessment

  • Note: GFP folding may be compromised in periplasmic locations

• Cysteine Scanning Mutagenesis:

  • Systematic replacement of residues with cysteine

  • Selective labeling with membrane-impermeable sulfhydryl reagents

  • Determination of cytoplasmic versus periplasmic exposure

  • Protocol requires Cys-less version of Bamb_1160 as starting template

• Protease Accessibility Assay:

  • Controlled proteolysis of spheroplasts versus intact cells

  • Western blot analysis of digestion patterns

  • Identification of exposed versus protected domains

  • Can be combined with epitope tagging strategies

• Immunolocalization Methods:

  • Generation of specific antibodies or use of anti-His for recombinant protein

  • Immunogold electron microscopy for precise localization

  • Fractionation followed by immunoblotting to determine membrane association

Computational Prediction Validation:

• Experimental validation of transmembrane domains predicted by programs like TMHMM, MEMSAT, or Phobius

• Comparison of experimental results with AlphaFold structural predictions

• Reconciliation of computational predictions with experimental data

Practical Considerations:

• Expression level control to avoid artifacts from overexpression

• Confirmation that tags/fusions don't disrupt native localization

• Use of multiple complementary approaches to build confidence in results

• Appropriate controls for each technique

These methodological approaches will provide crucial insights into how Bamb_1160 is integrated into the bacterial membrane, informing hypotheses about its functional role.

What are common challenges in obtaining soluble, functional recombinant Bamb_1160 and how can they be addressed?

Membrane proteins like Bamb_1160 present specific challenges in recombinant expression and purification. Here are common issues and solutions:

Challenge 1: Poor Expression Levels

Challenge 2: Protein Aggregation/Inclusion Bodies

Challenge 3: Purification Difficulties

Challenge 4: Functional Assessment

Recommended Workflow:

• Begin with multiple constructs (varying tags, positions)

• Screen expression conditions in small scale

• Optimize solubilization and purification for best-performing constructs

• Verify protein quality by multiple methods (SDS-PAGE, size exclusion chromatography, mass spectrometry)

• Establish functional assays based on predicted roles

These strategies help overcome the inherent challenges of working with membrane proteins like Bamb_1160.

What considerations are important when designing experiments to investigate potential interactions between Bamb_1160 and host cell components?

Investigating interactions between bacterial proteins like Bamb_1160 and host components requires careful experimental design to account for multiple complexities:

Host System Selection Considerations:

• Relevance to natural infection/colonization:

  • Human cell lines for studying opportunistic pathogen interactions

  • Plant cell systems for investigating rhizosphere interactions

  • Animal models for in vivo validation

• Cell type selection:

  • Epithelial cells (respiratory or intestinal) for mucosa interaction studies

  • Immune cells (macrophages, neutrophils) for host defense studies

  • Plant root cells for rhizosphere colonization studies

Experimental Design Framework:

Controls and Validation:

• Non-UPF0060 membrane proteins as negative controls

• Known interacting protein pairs as positive controls

• Multiple detection methods to confirm interactions

• Dose-dependency and kinetic analyses for quantitative assessment

• Correlation with infection/colonization phenotypes

Potential Pitfalls and Solutions:

• Artificial interactions due to overexpression: Use physiological expression levels

• Non-native conformations: Ensure proper membrane integration

• Indirect interactions: Distinguish direct from complex-mediated interactions

• Host response artifacts: Include appropriate controls for host cell stress responses

These considerations will help design robust experiments to investigate biologically relevant interactions between Bamb_1160 and host components.

What are promising research avenues for elucidating the functional role of Bamb_1160 in Burkholderia ambifaria?

Several promising research avenues can help elucidate the functional role of Bamb_1160:

1. Genetic Manipulation Approaches:

• CRISPR-Cas9 mediated gene knockout to assess essentiality and phenotypic effects

• Conditional expression systems to study effects of protein depletion

• Site-directed mutagenesis of conserved residues to identify functional domains

• Complementation studies with homologs from related species

2. Structural Biology Investigations:

• Cryo-EM analysis of purified protein in membrane-like environments

• X-ray crystallography following successful crystallization

• NMR studies of specific domains or peptide fragments

• Comparison with AlphaFold or RoseTTAFold predictions for validation

3. Functional Screening Approaches:

• Ligand binding assays using diverse chemical libraries

• Bacterial two-hybrid screens to identify interaction partners

• Phenotypic screening under various stress conditions

• Metabolomic analysis of knockout vs. wild-type strains

4. Systems Biology Integration:

• Transcriptomic analysis of differential gene expression in knockout strains

• Proteomics to identify changes in membrane protein composition

• Network analysis to position Bamb_1160 in cellular pathways

• Comparative genomics across Burkholderia species with different ecological niches

5. Host-Microbe Interaction Studies:

• Analysis of Bamb_1160 role in plant colonization

• Investigation of potential immunomodulatory effects

• Contribution to biofilm formation and persistence

• Role in environmental adaptation and stress responses

Expected Impact:
Elucidating Bamb_1160 function would provide insights into fundamental aspects of Burkholderia biology, potentially revealing:

• Novel membrane transport mechanisms

• Previously unknown signaling pathways

• Targets for antimicrobial development

• Determinants of environmental persistence and adaptation

How might Bamb_1160 be utilized as a target for developing new diagnostic methods for Burkholderia infections?

Bamb_1160 presents several opportunities for diagnostic method development, particularly given the clinical significance of Burkholderia infections:

Immunodiagnostic Approaches:

• Development of monoclonal antibodies against Bamb_1160

• Lateral flow immunochromatographic assays for rapid detection

• ELISA-based quantitative detection methods

• Immunofluorescence techniques for direct sample visualization

Nucleic Acid Detection Strategies:

• Species-specific PCR targeting bamb_1160 gene

• Isothermal amplification methods (LAMP, RAA) for point-of-care testing

• qPCR with high-resolution melt curve analysis for species differentiation

• Next-generation sequencing approaches for complex sample analysis

Emerging Technologies Applications:

• CRISPR-Cas12/Cas13-based detection systems

• Aptamer-based biosensors for Bamb_1160 detection

• Nanopore sequencing for rapid identification

• Mass spectrometry-based proteomic identification

Clinical Implementation Considerations:

Diagnostic Value Assessment:

• Specificity within the Burkholderia genus

• Sensitivity compared to current gold standards

• Performance in complex clinical specimens

• Correlation with viable bacterial counts

• Ability to differentiate BCC species

The development of Bamb_1160-based diagnostics could improve detection speed and accuracy for Burkholderia infections, particularly in high-risk populations such as cystic fibrosis patients and immunocompromised individuals.

What research gaps remain in understanding how membrane proteins like Bamb_1160 contribute to Burkholderia pathogenesis and environmental adaptation?

Several significant research gaps exist in understanding membrane proteins like Bamb_1160 in Burkholderia biology:

Fundamental Knowledge Gaps:

• Structure-Function Relationships

  • High-resolution structural data of UPF0060 family proteins in Burkholderia

  • Identification of functional domains and critical residues

  • Conformational changes during potential transport/signaling activities

• Regulatory Networks

  • Transcriptional regulation under various environmental conditions

  • Post-translational modifications affecting function

  • Integration with other cellular signaling systems

• Evolutionary Context

  • Selection pressures driving UPF0060 protein evolution

  • Horizontal gene transfer patterns across Burkholderia species

  • Adaptive significance in different ecological niches

Pathogenesis and Host Interaction Gaps:

• Contribution to Virulence

  • Role in survival within host cells

  • Involvement in immune evasion strategies

  • Potential recognition by host immune receptors

• Host Range Determinants

  • Factors influencing plant versus mammalian host specificity

  • Adaptation to different host microenvironments

  • Contribution to host switching capabilities

Environmental Adaptation Research Needs:

• Stress Response Mechanisms

  • Function during antimicrobial exposure

  • Adaptation to pH, temperature, and osmotic stress

  • Role in nutrient acquisition from diverse environments

• Community Interactions

  • Contribution to competitive fitness in polymicrobial communities

  • Role in biofilm formation and maintenance

  • Function in interspecies communication

Technological Challenges to Address:

• In vivo Functional Assessment

  • Development of suitable animal and plant models

  • Methods for tracking protein dynamics in real-time

  • Tools for manipulating membrane proteins in native contexts

• Multi-omics Integration

  • Correlation of genomic, transcriptomic, and proteomic data

  • Metabolic modeling incorporating membrane protein functions

  • Systems biology approaches to context-dependent function