Recombinant Chlorobaculum parvum ATP synthase subunit b (atpF)

What is the structure and function of Chlorobaculum parvum ATP synthase subunit b (atpF)?

Chlorobaculum parvum ATP synthase subunit b is a component of the F0 sector of ATP synthase, which functions as an electric rotary motor located inside the mitochondrial matrix with an ion pump to transfer protons across the cell membrane . While the search results focus primarily on the atpB1 subunit (subunit a), we can infer that the atpF (subunit b) plays a crucial role in the structural integrity and function of the F0 sector of ATP synthase.

The functional ATP synthase complex consists of two major components:

• F0: The membrane-embedded portion that forms the proton channel

• F1: The catalytic portion that synthesizes ATP in the mitochondrial matrix

Subunit b typically forms a peripheral stalk that connects the F1 and F0 sectors, helping to maintain the structural integrity of the complex during the rotational catalysis that drives ATP synthesis.

What expression systems are recommended for recombinant Chlorobaculum parvum ATP synthase subunit b?

Based on related research with Chlorobaculum parvum ATP synthase subunits, E. coli is the recommended expression system for recombinant production of ATP synthase components . When expressing recombinant Chlorobaculum parvum proteins, the following methodological considerations are important:

• Vector selection: Vectors containing N-terminal His-tags facilitate purification via affinity chromatography

• Expression conditions: Optimize temperature, IPTG concentration, and induction time

• Cell lysis: Use gentle lysis methods to preserve protein structure

• Purification strategy: Implement a multi-step purification protocol to achieve >90% purity

As observed with other Chlorobaculum parvum ATP synthase subunits, expression in E. coli provides good yields while maintaining the protein's structural integrity .

What storage conditions maximize stability of recombinant Chlorobaculum parvum ATP synthase subunit b?

Optimal storage conditions for recombinant Chlorobaculum parvum ATP synthase proteins include:

• Long-term storage: Store at -20°C/-80°C upon receipt

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

• Avoid repeated freeze-thaw cycles, which can significantly reduce protein activity

For reconstitution and storage preparation:

• Briefly centrifuge the vial prior to opening to bring contents to the bottom

• Reconstitute protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL

• Add 5-50% glycerol (final concentration) and aliquot for long-term storage

• The recommended final concentration of glycerol is 50%

How can I confirm the identity and purity of recombinant Chlorobaculum parvum ATP synthase subunit b?

Multiple analytical methods should be employed to verify identity and purity:

• SDS-PAGE: Should demonstrate >90% purity with a single prominent band at the expected molecular weight

• Western blotting: Using antibodies against the His-tag or specific antibodies against the protein

• Mass spectrometry: To confirm the amino acid sequence and post-translational modifications

• Activity assays: To verify functional integrity of the recombinant protein

What is the role of Chlorobaculum parvum ATP synthase in photosynthetic energy metabolism?

Chlorobaculum parvum is a green sulfur bacterium (GSB) that utilizes photosynthesis coupled with oxidative sulfur metabolism . ATP synthase plays a crucial role in this process:

• The proton gradient generated during photosynthetic electron transport drives ATP synthesis

• In GSB, ATP synthase is linked to sulfur oxidation pathways that generate additional proton motive force

• This system enables energy conservation during photolithoautotrophic growth on sulfide

The unique adaptation of ATP synthase in Chlorobaculum parvum reflects its specialized ecological niche and metabolic capabilities in sulfur-rich anaerobic environments.

What experimental approaches are effective for studying interactions between Chlorobaculum parvum ATP synthase subunit b and other components of the ATP synthase complex?

To investigate protein-protein interactions within the ATP synthase complex, researchers should consider the following methodological approaches:

• Co-immunoprecipitation with specific antibodies:

  • Express recombinant proteins with different tags

  • Use antibodies against one subunit to pull down interaction partners

  • Analyze by Western blotting or mass spectrometry

• Cross-linking coupled with mass spectrometry:

  • Apply bifunctional cross-linkers at optimized concentrations

  • Digest cross-linked complexes and analyze by LC-MS/MS

  • Identify cross-linked peptides to map interaction interfaces

• Surface plasmon resonance for binding kinetics:

  • Immobilize one subunit on the sensor chip

  • Measure association and dissociation constants

  • Determine binding affinities under various conditions

• Yeast two-hybrid or bacterial two-hybrid assays:

  • Create fusion constructs with DNA-binding and activation domains

  • Screen for interactions in vivo

  • Validate positive interactions with alternative methods

How can site-directed mutagenesis be applied to investigate functional domains of Chlorobaculum parvum ATP synthase subunit b?

Site-directed mutagenesis offers powerful insights into structure-function relationships. A comprehensive experimental approach should include:

• Rational design of mutations based on sequence conservation:

  • Analyze sequence alignments across multiple species

  • Target highly conserved residues for mutagenesis

  • Include both conservative and non-conservative substitutions

• Expression and purification of mutant proteins:

  • Use the same expression system as wild-type protein (E. coli recommended)

  • Purify using identical protocols to ensure comparability

  • Verify proper folding using circular dichroism spectroscopy

• Functional characterization of mutants:

  • Assess stability, oligomerization state, and interaction capacity

  • Measure ATP synthesis/hydrolysis activities

  • Determine proton translocation efficiency

• Structural analysis of mutants:

  • Compare structural changes using X-ray crystallography or cryo-EM

  • Use hydrogen-deuterium exchange mass spectrometry to assess conformational changes

  • Apply molecular dynamics simulations to predict impact on protein dynamics

What approaches can resolve challenges in expression and purification of functional recombinant Chlorobaculum parvum ATP synthase subunit b?

Membrane protein expression and purification presents unique challenges. The following methodological strategies can improve success:

• Optimization of expression constructs:

  • Test multiple fusion tags (His, GST, MBP) to improve solubility

  • Create truncated constructs to remove hydrophobic regions

  • Use synthetic genes with codon optimization for E. coli

• Expression condition screening:

  • Test induction at different cell densities (OD600 0.6-1.2)

  • Vary induction temperatures (16°C, 25°C, 30°C, 37°C)

  • Evaluate different inducer concentrations

  • Consider auto-induction media formulations

• Advanced purification strategies:

  • Implement gentle detergent solubilization (DDM, LDAO, etc.)

  • Use gradient elution during affinity chromatography

  • Apply size exclusion chromatography as a final polishing step

  • Consider on-column refolding for inclusion body purification

• Functional reconstitution:

  • Incorporate purified protein into liposomes

  • Measure proton pumping activity using pH-sensitive dyes

  • Assess ATP synthesis capacity in proteoliposomes

How does Chlorobaculum parvum ATP synthase subunit b compare to homologous proteins in other photosynthetic bacteria?

Comparative analysis of ATP synthase subunit b across photosynthetic bacteria reveals important evolutionary and functional insights:

• Sequence conservation patterns:

  • Green sulfur bacteria (GSB) like Chlorobaculum parvum show distinct sequence features compared to purple sulfur bacteria (PSB)

  • Regions involved in oligomerization and interaction with F1 sector are typically conserved

  • Terminal regions often contain species-specific adaptations

• Structural differences related to ecological niches:

  • GSB ATP synthase components have adapted to function in sulfide-rich anaerobic environments

  • Unique adaptations facilitate integration with sulfur metabolism pathways

  • Differences in proton-binding sites may reflect pH adaptations

• Functional implications of variations:

  • Different optimal temperature ranges for ATP synthase activity

  • Varied sensitivity to inhibitors

  • Differential stability under oxidative stress conditions

The differences in ATP synthase components between GSB like Chlorobaculum parvum and other photosynthetic bacteria reflect their evolutionary adaptations to specialized ecological niches and metabolic requirements.

What experimental design approaches are most effective for studying the role of Chlorobaculum parvum ATP synthase subunit b in energy coupling?

To investigate energy coupling mechanisms, researchers should implement:

• Reconstitution systems for bioenergetic measurements:

  • Incorporate purified ATP synthase components into liposomes

  • Establish proton gradients using light-driven proton pumps

  • Measure ATP synthesis rates under defined gradient conditions

• Adaptive experimental design approaches:

  • Implement sequential testing protocols that adapt based on initial results

  • Use Bayesian optimization to efficiently explore parameter space

  • Apply counterfactual inference to enhance experimental efficiency

• Coupling measurements in native-like systems:

  • Prepare inverted membrane vesicles from expression hosts

  • Measure ATP-driven proton pumping and proton gradient-driven ATP synthesis

  • Quantify H+/ATP stoichiometry under various conditions

• Mutational analysis of coupling elements:

  • Target residues at the interface between subunit b and other components

  • Evaluate effects on proton translocation and ATP synthesis

  • Correlate structural changes with altered coupling efficiency