Recombinant Burkholderia thailandensis Protein CrcB homolog (crcB)
Description
Fluoride Ion Transport and Stress Response
CrcB is implicated in fluoride ion efflux, a critical function for bacterial survival under fluoride stress. Fluoride inhibits metabolic enzymes like enolase, making CrcB essential for detoxification .
Contribution to Antibiotic Resistance
CrcB homologs interact with membrane potential homeostasis, influencing resistance to polymyxins (e.g., colistin). In B. thailandensis, the DedA family protein DbcA (dependent on CrcB-like functions) modulates proton motive force (PMF), which is required for lipid A modification with aminoarabinose (Ara4N). This modification reduces colistin susceptibility :
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Key Mechanism:
Genomic Context and Regulation
The crcB gene (locus BTH_I1520) is part of conserved operons in Burkholderia. Transcriptomic studies highlight its co-expression with stress-response genes during stationary phase, suggesting roles in nutrient limitation adaptation .
Biotechnological Relevance
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Protein Engineering: His-tagged CrcB facilitates high-yield purification for biochemical assays .
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Comparative Genomics: Orthologs in pathogenic Burkholderia (e.g., B. pseudomallei) provide insights into virulence evolution .
Limitations and Future Directions
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Functional Redundancy: CrcB’s role overlaps with other DedA family proteins (e.g., DbcA), complicating in vivo validation .
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Structural Gaps: No crystallographic data for B. thailandensis CrcB exists; homology modeling relies on E. coli CrcB (PDB: 4X5H) .
Future studies should prioritize structural resolution and in planta functional assays to elucidate CrcB’s role in host-pathogen interactions .
Product Specs
Note: We prioritize shipping the format currently in stock. However, if you have specific format requirements, please indicate them during order placement, and we will fulfill your request.
Note: All our proteins are shipped with standard blue ice packs by default. If you require dry ice shipping, please communicate this beforehand, as additional fees will apply.
Generally, the shelf life for the liquid form is 6 months at -20°C/-80°C. Lyophilized form has a shelf life of 12 months at -20°C/-80°C.
Target Background
KEGG: bte:BTH_I1520
Q&A
What is the most effective method to express recombinant CrcB homolog protein in Burkholderia thailandensis?
The expression of recombinant proteins in B. thailandensis can be achieved through several approaches, with the Mini-Tn7 transposon system showing particular effectiveness. This system successfully introduces gene constructs into the B. thailandensis genome at specific attachment sites. For optimal expression, the ribosomal protein S12 gene promoter (Ps12) is recommended as it drives constitutive expression in Burkholderia species . When designing expression constructs, it's critical to optimize codon usage for the high GC content (approximately 63%) typical of Burkholderia genomes, which significantly improves protein yield .
For CrcB specifically, cloning the optimized gene construct into the MiniTn7-kan plasmid backbone and introducing it via the Mini-Tn7 transposon system ensures stable genomic integration and reliable expression. This method has been validated in multiple studies of B. thailandensis protein expression and avoids the plasmid instability issues often encountered with other expression systems.
How can we verify successful expression of CrcB homolog protein in experimental systems?
Verification of CrcB expression can be achieved through several complementary techniques:
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Western blot analysis: Using antibodies specific to CrcB or to an epitope tag if incorporated in the recombinant design
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Mass spectrometry: For precise identification and quantification
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Bio-orthogonal noncanonical amino acid tagging (BONCAT): This technique enables selective labeling of newly synthesized proteins and has been successfully applied to B. thailandensis
BONCAT is particularly valuable as it allows for fluorescent tagging of proteins in situ and enrichment of newly expressed bacterial proteins from various growth conditions, including during host cell infection . When combined with MS/MS analysis, this method provides both visual confirmation and quantitative assessment of protein expression.
How does the expression of CrcB homolog change during different growth phases in B. thailandensis?
Transcriptome-proteome profiling studies of B. thailandensis reveal that bacterial cells undergo significant molecular changes during transition from exponential to stationary phase. While specific data for CrcB homolog is not directly reported in the literature, general patterns of protein expression during stationary phase can inform expectations:
| Growth Phase | Typical Protein Expression Patterns | Potential Implications for CrcB |
|---|---|---|
| Exponential Phase | Higher expression of proteins involved in translation, flagellar biosynthesis | May show baseline expression if involved in basic cellular functions |
| Early Stationary Phase | Upregulation of stress response genes, secondary metabolite production | May show altered expression if involved in stress response |
| Late Stationary Phase | Accumulation of proteins involved in fatty acid degradation, butanoate metabolism | May show differential regulation depending on its functional category |
Most notably, integrated analysis of transcriptomic and proteomic data shows only moderate correlation between mRNA and protein levels (Pearson correlation coefficient r = 0.4), suggesting significant post-translational regulation in B. thailandensis . This highlights the importance of studying CrcB at both the transcriptional and protein levels for comprehensive understanding.
How can researchers differentiate between direct CrcB homolog functions and pleiotropic effects in B. thailandensis?
Differentiating direct from pleiotropic effects requires a comprehensive analytical approach:
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Targeted gene deletion/complementation: Create ΔcrcB mutants and complemented strains to observe phenotypic changes
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Conditional expression systems: Use inducible promoters to control CrcB expression levels and timing
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Proteomic network analysis: Examine protein-protein interactions and co-expression patterns
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Comparative analysis across conditions: Analyze differential expression patterns between conditions as shown below:
| Comparison | Upregulated Proteins | Downregulated Proteins | Not Significant |
|---|---|---|---|
| RNA-Seq vs Proteomics | 150 proteins upregulated in both datasets | 30 proteins downregulated in both datasets | Many proteins show different patterns at mRNA vs protein levels |
This comparison table demonstrates that only a subset of proteins follow the same expression trends at both mRNA and protein levels in B. thailandensis, indicating extensive post-transcriptional regulation . For CrcB, this suggests that understanding its regulation requires both transcriptomic and proteomic analyses under varied conditions.
What role might CrcB homolog play in RecA-dependent genomic plasticity in B. thailandensis?
Recent research has identified a sophisticated phase variation system in B. thailandensis that generates phenotypically heterogeneous populations through RecA-mediated homologous recombination between insertion sequence (IS) elements . This system can duplicate a 208.6 kb region containing 157 coding sequences.
While specific involvement of CrcB in this process hasn't been directly established, researching potential connections would require:
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Genomic context analysis: Determine if crcB is located within or near the 208.6 kb duplicated region
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Expression correlation: Analyze whether CrcB expression changes correlate with RecA activity or genomic duplication events
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Phenotypic assessment: Compare ΔcrcB mutant strains to wild-type in terms of genomic plasticity and RecA-dependent recombination frequency
This investigation would contribute to understanding potential roles of CrcB in B. thailandensis adaptation to fluctuating environmental conditions through genomic architecture alterations.
How can BONCAT be optimized for studying CrcB homolog during host infection?
BONCAT optimization for studying CrcB homolog requires several key considerations:
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Construct development: The MetRS NLL gene from E. coli should be optimized for expression in Burkholderia by increasing GC content from approximately 52% to 63% without altering the amino acid sequence
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Promoter selection: The constitutive Ps12 promoter ensures reliable expression of MetRS NLL in B. thailandensis
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Noncanonical amino acid selection: Azidonorleucine (ANL) has proven effective for selective labeling of B. thailandensis proteins
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Timing optimization: The table below outlines recommended parameters for BONCAT labeling during different experimental phases:
| Experimental Phase | ANL Concentration | Labeling Duration | Sample Processing |
|---|---|---|---|
| Monoculture | 1-2 mM | 1-3 hours | Cell lysis, click chemistry with alkyne-biotin, affinity purification |
| Early Infection (0-4h) | 1-2 mM | 1-2 hours | Host cell lysis, bacterial enrichment, click chemistry |
| Established Infection (>4h) | 1.5-2 mM | 2-4 hours | Selective bacterial enrichment before processing |
This approach allows for selective enrichment of newly synthesized CrcB protein from infected host cells despite the overwhelming host protein content, providing a powerful tool to study the molecular processes during Burkholderia infection .
What integrative analytical approaches can best reveal CrcB homolog regulation networks?
Integrative analysis of transcriptomic and proteomic data provides comprehensive insights into protein regulation networks. For CrcB homolog, the following methodology is recommended:
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Combined RNA-Seq and quantitative proteomics: Analyze correlation between mRNA and protein levels across multiple conditions
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Correlation assessment: Calculate Pearson correlation coefficients between transcriptomic and proteomic data (typical r = 0.4 for B. thailandensis)
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Pathway enrichment analysis: Identify biological processes and molecular functions associated with CrcB
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Regulatory network construction: Example from B. thailandensis stationary phase shows:
| Regulation Category | Number of Proteins | Percentage with Matching mRNA Changes | Examples of Processes |
|---|---|---|---|
| Upregulated Proteins | 552 | 27.2% (150 proteins) | Benzoate degradation, O-antigen biosynthesis |
| Downregulated Proteins | 280 | 10.7% (30 proteins) | Ribosomal proteins, iron-sulfur biogenesis |
| Inversely Regulated | 4 | - | Minimal occurrences suggest strong coordination |
The modest correlation between transcriptome and proteome changes observed in B. thailandensis suggests significant post-translational regulation , highlighting the importance of protein-level studies for CrcB function understanding.
What approaches are most effective for studying CrcB homolog localization in B. thailandensis?
Determining subcellular localization of CrcB requires multiple complementary techniques:
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Fluorescent protein fusions: C-terminal or N-terminal GFP fusions allowing in vivo visualization
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Immunofluorescence microscopy: Using antibodies specific to CrcB or epitope tags
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Subcellular fractionation followed by Western blotting: Physical separation of cellular compartments
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BONCAT with compartment-specific enrichment: Combining selective protein labeling with subcellular fractionation
For studying localization changes during infection, the BONCAT technique is particularly valuable as it allows for fluorescent tagging of newly synthesized CrcB protein in situ and subsequent visualization via microscopy . This approach can reveal dynamic changes in protein localization during different stages of host cell infection or under various environmental stresses.
How should researchers interpret contradictory results between transcriptomic and proteomic data for CrcB homolog?
The integration of transcriptomic and proteomic data often reveals discrepancies that require careful interpretation. Studies in B. thailandensis show only moderate correlation (Pearson r = 0.4) between mRNA and protein levels , suggesting significant post-transcriptional regulation.
When encountering contradictory results for CrcB homolog:
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Consider temporal dynamics: Transcriptional changes often precede protein-level changes
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Evaluate post-transcriptional regulation: Analyze potential RNA-binding proteins or small RNAs affecting translation
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Assess protein stability factors: Proteins with longer half-lives may maintain stable levels despite transcriptional changes
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Examine methodological limitations: Different sensitivities between RNA-Seq and MS-based proteomics can contribute to apparent discrepancies
For robust interpretation, researchers should validate findings using targeted approaches such as RT-qPCR for transcript levels and Western blotting or targeted proteomics for protein levels under identical conditions.
What statistical approaches are most appropriate for analyzing CrcB expression data across different experimental conditions?
| Analysis Type | Recommended Statistical Method | Application Scenario |
|---|---|---|
| Two-condition comparison | Paired t-test or Wilcoxon signed-rank test | Comparing CrcB expression before/after infection |
| Multi-condition analysis | ANOVA with post-hoc tests (Tukey's HSD) | Comparing expression across multiple time points |
| Correlation analysis | Pearson or Spearman correlation | Relating CrcB expression to other proteins/phenotypes |
| Multiple testing correction | Benjamini-Hochberg procedure | Controlling false discovery rate in proteome-wide analysis |
When analyzing spectral counting data from label-free proteomics, researchers should ensure high reproducibility between biological replicates as observed in B. thailandensis studies (good correlation even with two-fold differences in total spectra between replicates) .
For experimental designs evaluating CrcB function, the Solomon Four-Group Design offers particularly robust statistical power by controlling for multiple threats to validity while enabling diverse analytical comparisons .
What emerging technologies show promise for advanced study of CrcB homolog function in B. thailandensis?
Several cutting-edge approaches hold significant potential for advancing CrcB research:
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CRISPR-Cas9 genome editing: Precise manipulation of the crcB gene and regulatory elements
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Proximity-dependent biotin labeling (BioID or TurboID): Identifying protein-protein interactions in living cells
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Single-cell proteomics: Revealing cell-to-cell variability in CrcB expression
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Advanced microscopy techniques: Super-resolution imaging of protein localization and dynamics
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Machine learning approaches: Predicting protein functions and interactions based on integrated omics data
These technologies, when combined with established methods like BONCAT for selective protein labeling , offer powerful new avenues for understanding CrcB's role in B. thailandensis biology, particularly during host infection or environmental stress adaptation.
How might research on CrcB homolog contribute to understanding B. thailandensis adaptation mechanisms?
Research on CrcB homolog could provide valuable insights into several adaptation mechanisms:
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Genomic plasticity: Investigation of potential roles in the RecA-dependent phase variation system that creates genotypically heterogeneous populations through IS element recombination
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Stress response: Analysis of CrcB expression changes during stationary phase, when bacteria typically upregulate stress response mechanisms
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Host-pathogen interactions: Examination of CrcB regulation during infection to understand survival strategies within host cells
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Environmental adaptation: Study of CrcB function under varying conditions to elucidate its contribution to B. thailandensis versatility
Understanding these mechanisms has broader implications for research on related pathogenic Burkholderia species, as B. thailandensis serves as a valuable surrogate for highly pathogenic B. pseudomallei and B. mallei, which are considered biothreat agents of concern .
