Recombinant Helicobacter acinonychis ATP synthase subunit c (atpE)

What is the evolutionary relationship between H. acinonychis atpE and similar genes in other Helicobacter species?

The atpE gene in H. acinonychis shares significant homology with its counterpart in H. pylori, reflecting their close evolutionary relationship. Genomic analyses reveal that H. acinonychis is very closely related to H. pylori, with pair-wise estimates of only 3-4% for DN (the frequency of non-synonymous nucleotide polymorphisms) across 612 orthologous coding sequences present in both species . This close relationship extends to the ATP synthase genes, including atpE.

For researchers investigating this relationship, methods should include:

• Comparative sequence analysis using tools like BLAST to align atpE sequences from multiple Helicobacter species

• Phylogenetic analysis to reconstruct the evolutionary history of atpE

• Analysis of selection pressure (dN/dS ratios) to identify conserved functional domains

• Structural modeling to predict effects of sequence variations on protein function

How does the structure of H. acinonychis ATP synthase c-subunit compare to those of related bacteria?

While specific structural data for H. acinonychis ATP synthase c-subunit is limited, comparative analysis with related species provides valuable insights. The c-subunit typically forms a ring structure consisting of 10-15 identical subunits (depending on the species), each containing two transmembrane helices and a conserved glutamic acid residue critical for proton binding.

Methodological approaches for structural comparisons include:

• Homology modeling using solved structures from related bacteria

• Circular dichroism spectroscopy to determine secondary structure content

• NMR spectroscopy or X-ray crystallography for high-resolution structural determination

• Molecular dynamics simulations to study conformational dynamics

What expression systems are optimal for producing recombinant H. acinonychis ATP synthase subunit c?

Expression of functional recombinant H. acinonychis ATP synthase subunit c requires careful consideration of expression systems due to its hydrophobic nature and oligomeric assembly properties.

Recommended methodological approaches include:

• Testing multiple expression systems (E. coli, yeast, cell-free systems)

• For E. coli expression, utilize specialized strains like C41(DE3) or C43(DE3) designed for membrane protein expression

• Optimize induction conditions (temperature, IPTG concentration, induction time)

• Employ fusion tags (maltose-binding protein, thioredoxin) to enhance solubility

• Consider codon optimization based on H. acinonychis codon usage preferences

For purification:

• Use detergent screening to identify optimal solubilization conditions

• Implement multiple chromatography steps (affinity, ion exchange, size exclusion)

• Verify protein integrity through mass spectrometry and N-terminal sequencing

What is the role of conserved glutamic acid residues in the c-subunit function?

Conserved glutamic acid residues in ATP synthase c-subunits play a critical role in proton translocation. Research with Bacillus PS3 ATP synthase demonstrated that mutation of the conserved glutamic acid (E56) significantly affects function .

Experimental approaches to study these residues in H. acinonychis include:

• Site-directed mutagenesis to create E→D or E→Q mutations

• ATP synthesis and proton pump activity assays to measure functional impact

• pH-dependent structural studies to monitor protonation effects

• Molecular dynamics simulations to model proton transfer mechanisms

Data from Bacillus PS3 studies showed that E56D mutation reduced but did not eliminate ATP synthesis activity, while E56Q substitution completely abolished function, highlighting the importance of the carboxyl group for protonation/deprotonation cycles .

How do interactions between c-subunits contribute to the rotational mechanism of H. acinonychis ATP synthase?

Research on ATP synthase c-subunits from other organisms reveals crucial cooperation among c-subunits during rotation. Studies with Bacillus PS3 ATP synthase demonstrate that multiple c-subunits cooperate in the rotation mechanism, with functional coupling between neighboring subunits .

Methodological approaches to investigate this in H. acinonychis include:

• Generation of genetically fused single-chain c-rings with controlled introduction of mutations

• Analysis of proton translocation efficiency in wildtype versus mutant proteins

• Single-molecule rotation assays using fluorescence microscopy

• Cross-linking studies to capture different rotational states

Data from Bacillus PS3 research shows activity correlates with the positioning of mutations:

These findings suggest that separation distance between mutations affects function, indicating cooperative mechanisms .

What structural adaptations in the c-subunit might facilitate H. acinonychis survival in the feline gastric environment?

H. acinonychis evolved from H. pylori after a host jump from humans to large felines , potentially requiring adaptations in ATP synthase to function in the different gastric environment.

Research approaches should include:

• Comparative analysis of c-subunit sequences from H. acinonychis strains isolated from different feline hosts

• pH-dependent functional assays comparing H. acinonychis and H. pylori ATP synthases

• Identification of amino acid substitutions unique to H. acinonychis ATP synthase subunits

• Testing recombinant protein stability and function under varying pH and ionic conditions

How does the c-subunit interact with other components of the H. acinonychis ATP synthase complex?

In H. pylori, ATP synthase components interact with cell shape proteins, suggesting integrated functions beyond ATP synthesis . Similar interaction networks may exist in H. acinonychis.

Methodological approaches include:

• Co-immunoprecipitation followed by mass spectrometry (IP-MS)

• Bacterial two-hybrid screening

• Chemical cross-linking coupled with mass spectrometry

• Cryo-electron microscopy of the entire ATP synthase complex

The H. pylori study identified interactions between cell shape protein Csd5 and multiple ATP synthase components:

Similar interaction studies with H. acinonychis ATP synthase components would reveal potential functional adaptations specific to feline host environments .

What role might ATP synthase play in the pathogenicity of H. acinonychis in feline hosts?

While H. acinonychis lacks some virulence factors found in H. pylori (the cag pathogenicity island and functional vacuolating cytotoxin) , its ATP synthase may contribute to pathogenesis through mechanisms such as pH homeostasis and energy production under stress conditions.

Research approaches should include:

• Construction of ATP synthase-deficient H. acinonychis mutants

• Infection models using feline gastric cell lines

• Transcriptomic analysis comparing wild-type and ATP synthase-deficient strains

• Metabolomic profiling to identify ATP synthase-dependent metabolic adaptations

What are the optimal conditions for measuring enzymatic activity of recombinant H. acinonychis ATP synthase c-subunit?

Measuring the enzymatic activity of recombinant H. acinonychis ATP synthase c-subunit requires reconstitution into a functional complex or liposomes.

Methodological recommendations include:

• Reconstitution of purified c-subunit with other ATP synthase components

• Preparation of proteoliposomes with controlled lipid composition

• ATP synthesis assays using acid-base transition methods

• ATP hydrolysis assays using coupled enzyme systems

• Proton pump activity measurements using pH-sensitive fluorescent dyes

Critical parameters to optimize:

• pH (typically 6.5-8.0 for ATP synthesis)

• Temperature (30-45°C)

• Lipid composition (phosphatidylethanolamine, phosphatidylglycerol, cardiolipin)

• Buffer composition (K+, Na+, Mg2+ concentrations)

How can site-directed mutagenesis be used to probe structure-function relationships in H. acinonychis ATP synthase subunit c?

Site-directed mutagenesis offers powerful insights into c-subunit function. Research with Bacillus PS3 demonstrated that mutations in the conserved glutamic acid residue (E56) significantly impact function .

Recommended methodological approach:

• Identify conserved residues through sequence alignment with related bacteria

• Design primers for QuikChange or Gibson Assembly mutagenesis

• Focus on conserved glutamic acid residues (equivalent to E56 in Bacillus PS3)

• Create single and double mutations at varying distances in the c-ring

• Use genetic fusion approaches to create single-chain c-rings with controlled mutation placement

Assays to evaluate mutant effects:

• ATP synthesis activity measurement

• Proton pumping efficiency

• Thermostability analysis

• Structural analysis using circular dichroism

What approaches can be used to study the oligomerization properties of H. acinonychis ATP synthase c-subunit?

The c-subunit forms an oligomeric ring critical for ATP synthase function. Understanding oligomerization is essential for characterizing this protein.

Methodological approaches include:

• Native gel electrophoresis with varying detergent concentrations

• Size exclusion chromatography with multi-angle light scattering

• Analytical ultracentrifugation

• Mass spectrometry under native conditions

• Cross-linking followed by SDS-PAGE or mass spectrometry

• Creation of genetically fused c-subunits (as in Bacillus PS3 studies)

How can researchers differentiate between effects on c-subunit structure versus effects on subunit interactions when analyzing mutational data?

Distinguishing structural effects from interaction effects requires multiple complementary approaches.

Recommended methodological strategies:

• Combine structural analyses (circular dichroism, thermal stability) with functional assays

• Use genetic fusion of c-subunits to control subunit positioning

• Implement disulfide cross-linking to assess specific subunit interactions

• Apply molecular dynamics simulations to predict effects of mutations

• Analyze cooperative effects between distant mutations

Data from Bacillus PS3 research showed that activity decreased as distance between double mutations increased, indicating cooperative mechanisms rather than simple additive structural effects .

What bioinformatic approaches are most effective for analyzing evolutionary patterns in ATP synthase c-subunits across Helicobacter species?

Bioinformatic analysis of ATP synthase c-subunits can reveal evolutionary adaptations and functional constraints.

Recommended methodological approaches:

• Multiple sequence alignment of c-subunits from diverse Helicobacter species

• Calculation of conservation scores for each amino acid position

• Analysis of co-evolving residues using methods like Statistical Coupling Analysis

• Identification of selection signatures using dN/dS analysis

• Ancestral sequence reconstruction to infer evolutionary changes

H. acinonychis and H. pylori show approximately 8% difference in gene sequences across shared orthologous genes , providing a framework for evolutionary analysis.

How should researchers address contradictory results between in vitro and in vivo studies of H. acinonychis ATP synthase function?

Discrepancies between in vitro and in vivo results are common in ATP synthase research due to the complex nature of the enzyme and its membrane environment.

Methodological recommendations:

• Validate protein folding and oligomeric state using multiple biophysical techniques

• Compare different reconstitution systems (nanodiscs, liposomes, native membranes)

• Verify results across multiple independent protein preparations

• Implement genetic complementation studies in ATP synthase-deficient bacteria

• Consider host-specific factors that may influence function in vivo