Recombinant Campylobacter concisus ATP synthase subunit a (atpB)

What is the structural composition of C. concisus ATP synthase subunit a (atpB)?

C. concisus ATP synthase subunit a (atpB) is a membrane-embedded component of the F0 sector of the ATP synthase complex. The full-length protein consists of 227 amino acids with a molecular weight of approximately 25 kDa. The amino acid sequence reveals a highly hydrophobic protein with multiple transmembrane domains, characteristic of F-type ATP synthase a subunits . The protein contains several hydrophobic segments that span the membrane, with the sequence: MKDLFLFSNLLNHSHAFVYAFHFCLVALIILIVAYIARSKMQLVPRGLQNIVEAYLEGVISMGKDTLGSEKLARKYLPLVATIGFIVFFSNVIGIIPGFESPSSSLNLTLVLALVVFIYNFEGIRENGFFKYFGHFMGPNKFLAPIMFPVEVISHLSRVVSLSFRLFGNIKGDDLFLLAMLTLAPWFAPLPAFALLTLMAVLQTFIFMMLTYVYLAGAVAISEHEH .

What is the functional significance of atpB in C. concisus metabolism?

The atpB protein functions as a critical component of the ATP synthase complex in C. concisus, which is essential for energy metabolism. As part of the F0 sector, atpB facilitates proton translocation across the membrane, which drives ATP synthesis through the F1 sector of the complex. In C. concisus, this energy generation system is particularly important given the organism's adaptability to different respiratory conditions. The pathogen can grow under both microaerobic and anaerobic conditions, with the latter requiring alternative electron acceptors . The ATP synthase complex, including atpB, would be crucial for maintaining energy homeostasis under these varying conditions, supporting the organism's colonization of the human oral-gastrointestinal tract .

How is recombinant C. concisus atpB typically expressed for research applications?

Recombinant C. concisus atpB is typically expressed in heterologous systems such as E. coli, which provides a controlled environment for protein production. The product information indicates that full-length atpB (amino acids 1-227) can be successfully expressed with an N-terminal His tag in E. coli . This approach allows for efficient purification using affinity chromatography. The expressed protein is then typically processed into a lyophilized powder for storage and distribution . For optimal expression, researchers should consider codon optimization for E. coli and carefully control induction conditions to balance protein yield with proper folding, particularly for this highly hydrophobic membrane protein.

What purification protocols yield the highest quality recombinant C. concisus atpB?

The most effective purification protocol for recombinant C. concisus atpB typically involves:

• Affinity chromatography using the N-terminal His tag to capture the protein from E. coli lysates

• Detergent solubilization to maintain protein stability during extraction from membranes

• Size exclusion chromatography to remove aggregates and improve homogeneity

• Buffer optimization to maintain protein stability

The purified protein can achieve >90% purity as determined by SDS-PAGE . For downstream applications requiring higher purity, additional chromatography steps such as ion exchange may be necessary. The choice of detergent is critical for maintaining the native structure of this membrane protein during purification and subsequent experiments.

What are the optimal storage conditions for maintaining recombinant C. concisus atpB stability?

Based on the product information, recombinant C. concisus atpB should be stored as follows:

The recommended reconstitution protocol involves:

• Brief centrifugation of the vial before opening

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

• Addition of glycerol to a final concentration of 5-50% (ideally 50%) for long-term storage

• Aliquoting to minimize freeze-thaw cycles, which can significantly reduce protein activity

What analytical methods are most effective for assessing C. concisus atpB function in vitro?

Multiple complementary approaches are recommended for comprehensive functional assessment:

• ATP synthesis/hydrolysis assays: Measuring ATP production or consumption in reconstituted proteoliposomes containing purified atpB along with other ATP synthase components.

• Proton translocation assays: Using pH-sensitive fluorescent dyes to monitor proton movement across membranes containing integrated atpB.

• Binding studies: Isothermal titration calorimetry (ITC) or surface plasmon resonance (SPR) to evaluate interactions with other ATP synthase components or potential inhibitors.

• Structural analysis: Circular dichroism (CD) spectroscopy to assess secondary structure integrity, particularly important for confirming proper folding of this highly hydrophobic membrane protein.

• Protein-protein interaction studies: Co-immunoprecipitation or crosslinking experiments to map the interactions of atpB within the larger ATP synthase complex.

When interpreting results, it's important to consider the challenges inherent in working with membrane proteins and potential differences between in vitro and in vivo behaviors.

How does atpB contribute to C. concisus adaptation to different respiratory environments?

C. concisus demonstrates remarkable adaptability to both microaerobic and anaerobic environments within the human oral-gastrointestinal tract . The ATP synthase complex, including atpB, likely plays a significant role in this adaptation through:

• Modulation of ATP synthesis efficiency under different oxygen conditions

• Adaptation to varying proton gradients generated by different respiratory chains

• Potential structural adjustments to optimize function in different membrane environments

Research has shown that C. concisus utilizes various N- or S-oxides as terminal electron acceptors under anaerobic conditions . While the study focused primarily on the BisA protein's dual role in N-/S-oxide-supported respiration and protein repair, the ATP synthase complex would necessarily interact with these respiratory pathways to maintain energy homeostasis. This interaction represents an important area for investigation, potentially contributing to understanding how C. concisus successfully colonizes diverse niches within the human gastrointestinal tract.

What structural or functional differences exist between atpB from different C. concisus strains?

Comparative analysis of atpB sequences from different C. concisus strains can reveal:

• Conserved regions likely essential for core functions

• Variable regions potentially associated with strain-specific adaptations

• Patterns of selection pressure indicating functional constraints or adaptations

The search results mention that C. concisus has been analyzed across multiple strains (23 genome sequences were examined for another protein, BisA) . Similar comparative genomic approaches could be applied to atpB. Research on C. concisus has identified substantial differences between oral and intestinal strains in other proteins, like the absence of bisA in the oral strain 33237 compared to intestinal strains 13826 and 51562 . It would be valuable to investigate whether similar strain-specific differences exist in atpB structure or expression patterns, potentially contributing to niche-specific adaptations.

How can researchers effectively generate and validate C. concisus atpB mutants?

Based on the mutagenesis approach described for other C. concisus genes, an effective strategy for generating atpB mutants would involve:

• Design of targeting constructs: PCR amplification of DNA sequences (400-850 bp) flanking the atpB gene, combined with a selectable marker such as a chloramphenicol resistance (cat) cassette .

• DNA methylation: Treatment of the targeting construct with cell-free extract from C. concisus in the presence of S-adenosylmethionine (SAM) to protect the DNA from restriction enzymes .

• Transformation: Introduction of methylated DNA into C. concisus via natural transformation or electroporation (2,500 V/pulse) .

• Selection and verification: Initial plating on blood agar, followed by transfer to selective media containing chloramphenicol (8-10 μg/mL), with confirmation by PCR .

Validation should include:

• PCR verification of gene deletion and marker insertion

• Phenotypic characterization focusing on growth rates under different respiratory conditions

• Complementation studies to confirm phenotypes are specifically due to atpB disruption

• Proteomic analysis to assess effects on ATP synthase complex assembly

What approaches can resolve contradictory data regarding atpB function in different experimental systems?

When faced with contradictory results regarding C. concisus atpB function, researchers should:

• Standardize experimental conditions: Systematically control variables such as strain background, growth conditions, protein expression levels, and assay parameters.

• Use multiple complementary techniques: Apply independent methodologies to measure the same parameter, such as combining biochemical assays with genetic approaches and structural studies.

• Consider strain-specific differences: As observed with the BisA protein, significant functional differences can exist between C. concisus strains . Testing atpB from multiple strains under identical conditions may reveal genuine biological variation rather than experimental inconsistency.

• Examine protein-protein interactions: The function of atpB depends on its interactions within the ATP synthase complex. Differences in associated proteins between experimental systems could explain functional discrepancies.

• Control for post-translational modifications: Identify and account for any modifications that might affect protein function, particularly when comparing recombinant proteins to native forms.

A structured approach to resolving contradictions might involve creating a comprehensive matrix of experimental variables and systematically testing their influence on measured outcomes.

How does atpB potentially contribute to C. concisus pathogenicity in gastrointestinal diseases?

As an emerging pathogen found throughout the human oral-gastrointestinal tract , C. concisus relies on efficient energy metabolism for successful colonization and potential pathogenicity. The ATP synthase complex, including atpB, likely contributes to pathogenicity through:

• Supporting growth and proliferation in diverse niches within the gastrointestinal tract

• Enabling adaptation to changing conditions during infection and inflammation

• Maintaining energy homeostasis during stress responses, including host immune challenges

C. concisus has been associated with inflammatory bowel disease and other gastrointestinal conditions . While direct evidence for atpB's role in pathogenicity is limited in the provided search results, ATP synthase inhibition has been shown to attenuate virulence in other bacterial pathogens. The unique adaptations of C. concisus ATP synthase to the gastrointestinal environment could represent potential targets for therapeutic intervention.

What experimental models best assess the immunological significance of C. concisus atpB?

Given that C. concisus proteins can be immunoreactive , researchers investigating potential immunological roles of atpB should consider:

• Human serum antibody profiling: Screening for anti-atpB antibodies in patients with C. concisus-associated gastrointestinal diseases compared to healthy controls.

• Immune cell stimulation assays: Examining responses of human immune cells (particularly dendritic cells and macrophages) to purified recombinant atpB.

• Epitope mapping: Identifying immunodominant regions of atpB that might stimulate B or T cell responses.

• Animal models: While challenging due to host specificity, modified mouse models could be developed to study immune responses to C. concisus, including atpB-specific responses.

• Comparative immunoproteomics: Building on previous work that identified immunoreactive proteins of C. concisus , researchers could specifically examine atpB immunoreactivity across patient cohorts.

These approaches would help determine whether atpB contributes to immune recognition of C. concisus and potentially to inflammatory responses associated with gastrointestinal diseases.

How does atpB function integrate with other metabolic pathways in C. concisus?

The ATP synthase complex containing atpB interfaces with multiple metabolic pathways in C. concisus, particularly:

• Respiratory chains: C. concisus can utilize various electron transport systems depending on available terminal electron acceptors. Under anaerobic conditions, the organism can use N- or S-oxides as terminal electron acceptors , which would generate the proton gradient that drives ATP synthesis via the complex containing atpB.

• Central carbon metabolism: ATP produced by the ATP synthase complex fuels various biosynthetic pathways and cellular functions.

• Stress response systems: Energy generation is critical during oxidative stress. The research on BisA indicated that C. concisus possesses mechanisms to deal with oxidative stress , which would require coordinated function with energy-generating systems including ATP synthase.

• Cell division processes: The search results mention that C. concisus contains Met-rich proteins annotated as "septum formation initiator" and "cell division protein" . Cell division is an energy-intensive process requiring ATP generated through the complex containing atpB.

Understanding these integrated networks would benefit from systems biology approaches combining transcriptomics, proteomics, and metabolomics under various growth conditions.

What computational approaches can best predict atpB structure-function relationships?

Advanced computational methods for investigating C. concisus atpB include:

• Homology modeling: Using structures of ATP synthase subunit a from related organisms as templates to predict C. concisus atpB structure.

• Molecular dynamics simulations: Modeling protein behavior in membrane environments to predict conformational changes during proton translocation.

• Protein-protein docking: Predicting interactions between atpB and other ATP synthase components to understand complex assembly and function.

• Evolutionary analysis: Examining conservation patterns across species to identify functionally important residues and domains.

• Machine learning approaches: Training algorithms on known structure-function relationships in related proteins to predict functional impacts of mutations or structural variations in C. concisus atpB.

These computational predictions should ideally guide experimental validation through site-directed mutagenesis and functional assays.

What are the most promising approaches for targeting C. concisus atpB in antimicrobial research?

Future antimicrobial strategies targeting C. concisus atpB might include:

• Structure-based drug design: Using computational and structural biology to identify compounds that selectively bind to C. concisus atpB and disrupt ATP synthase function.

• Peptide inhibitors: Developing synthetic peptides that mimic natural interaction partners of atpB but disrupt proper complex assembly or function.

• Combination therapies: Targeting atpB alongside other C. concisus-specific factors, such as the BisA protein that plays a dual role in N-/S-oxide-supported respiration and protein repair .

• Immunotherapeutic approaches: If atpB proves to be immunogenic, developing antibody-based approaches that recognize accessible portions of the protein.

• Metabolic adjustment: Designing strategies that alter the proton gradient upon which ATP synthase depends, indirectly affecting atpB function.

Success in these approaches would require careful consideration of specificity to avoid disrupting human ATP synthase while effectively targeting the bacterial complex.

What technological advances would most benefit C. concisus atpB research?

Several technological developments would substantially advance research on C. concisus atpB:

• Improved membrane protein structural biology techniques: Enhanced cryo-EM or crystallography methods specifically optimized for challenging membrane proteins like atpB.

• Single-molecule biophysics: Technologies for real-time monitoring of individual ATP synthase complexes to capture dynamic structural changes during function.

• Genetic manipulation tools: More efficient and precise methods for C. concisus genetic modification, building upon the described three-step mutagenesis strategy .

• In vivo imaging techniques: Methods to visualize ATP synthase distribution and activity in living C. concisus cells under various conditions.

• Microfluidic systems: Platforms that can mimic the microenvironments of the human gastrointestinal tract to study atpB function under physiologically relevant conditions.

These technological advances would help overcome current limitations in understanding membrane protein function in this emerging pathogen.