Recombinant Sorangium cellulosum ATP synthase subunit delta (atpH)

What is the ATP synthase subunit delta (atpH) in Sorangium cellulosum?

ATP synthase subunit delta (atpH) is a component of the ATP synthase complex (Complex V) in Sorangium cellulosum. This protein is part of the F1 domain of ATP synthase, which is responsible for ATP synthesis using the energy created by the proton electrochemical gradient. The protein is also known as ATP synthase F(1) sector subunit delta or F-type ATPase subunit delta . The complete protein sequence consists of 180 amino acids and has a UniProt accession number of A9GHR9 . ATP synthase as a complete complex consists of two functional domains: F1, situated in the matrix or cytoplasm, and Fo, located in the membrane, together forming the rotary nanomotor responsible for ATP production .

How does the atpH subunit contribute to ATP synthase function?

The delta subunit of ATP synthase plays a critical role in connecting the F1 and Fo domains of the enzyme complex. It functions as part of the central stalk that transmits the rotational energy generated by proton flow through Fo to the catalytic sites in F1. This central stalk rotation drives conformational changes in the catalytic β subunits, facilitating ATP synthesis from ADP and inorganic phosphate . In mitochondrial ATP synthase, the proper assembly and interaction of subunits are essential for complex formation and stability, with subunits playing roles in both the mechanical function and the stabilization of the holocomplex .

What expression systems are most effective for producing recombinant Sorangium cellulosum atpH?

Recombinant Sorangium cellulosum ATP synthase subunit delta can be effectively produced using either yeast or baculovirus expression systems, as evidenced by commercial preparations . The baculovirus expression system offers advantages for expressing complex prokaryotic proteins as it provides eukaryotic post-translational modifications while maintaining high protein yields. For the expression of full-length atpH protein (region 1-180), both systems appear viable, though the choice may depend on downstream applications and required protein modifications . When designing expression constructs, researchers should consider potential tag additions, which may be determined during the manufacturing process to optimize protein solubility and purification efficiency.

What purification methods yield the highest purity for recombinant atpH?

Standard purification protocols for recombinant Sorangium cellulosum ATP synthase subunit delta typically achieve purity levels exceeding 85% as determined by SDS-PAGE analysis . A multi-step purification process is recommended, including initial capture by affinity chromatography (based on the attached tag), followed by polishing steps such as ion exchange and size exclusion chromatography. For quality control, SDS-PAGE analysis provides critical purity assessment, with protein identity confirmation via mass spectrometry or western blotting with specific antibodies. When designing purification protocols, researchers should optimize buffer conditions to maintain protein stability throughout the process, particularly considering the native environment of this membrane-associated protein complex component.

What are the optimal storage conditions for maintaining atpH stability and activity?

For optimal stability of recombinant Sorangium cellulosum ATP synthase subunit delta, storage at -20°C is recommended, with extended storage at either -20°C or -80°C . Working aliquots can be maintained at 4°C for up to one week to avoid repeated freeze-thaw cycles, which can significantly compromise protein integrity . For reconstitution, the protein should be dissolved in deionized sterile water to a concentration of 0.1-1.0 mg/mL, with the addition of 5-50% glycerol (final concentration) for long-term storage . This glycerol addition serves as a cryoprotectant to prevent ice crystal formation that could denature the protein during freeze-thaw cycles.

How does the shelf life of recombinant atpH vary under different storage formats?

The shelf life of recombinant Sorangium cellulosum ATP synthase subunit delta varies significantly depending on its formulation. In liquid form, the protein typically maintains stability for approximately 6 months when stored at -20°C to -80°C . In contrast, the lyophilized (freeze-dried) format extends the shelf life to approximately 12 months under the same temperature conditions . Multiple factors influence protein stability, including buffer composition, presence of stabilizing additives, storage temperature, and the intrinsic stability of the protein itself. Researchers should monitor protein activity and structural integrity over time using appropriate functional assays and structural analyses if long-term storage is required for extended research projects.

How can recombinant atpH be used to study ATP synthase assembly in bacterial systems?

Recombinant Sorangium cellulosum ATP synthase subunit delta can serve as a valuable tool for investigating ATP synthase assembly mechanisms. Researchers can use fluorescently labeled recombinant atpH in pull-down assays to identify interaction partners within the ATP synthase complex. Site-directed mutagenesis of specific residues in the recombinant protein, followed by assembly studies, can help identify critical regions for subunit-subunit interactions. The protein can also be employed in complementation studies with delta-subunit-deficient bacterial strains to assess functional conservation across species . When designing such experiments, researchers should consider that ATP synthase exists in di- and oligomeric states, which may influence assembly pathways and protein-protein interactions .

What methods are most effective for studying atpH interactions with other ATP synthase subunits?

Several complementary approaches can be employed to investigate the interactions between atpH and other ATP synthase subunits:

• Crosslinking studies: Using chemical crosslinkers of various lengths to identify proximity relationships between atpH and neighboring subunits

• Surface plasmon resonance (SPR): For quantitative measurement of binding kinetics and affinities between atpH and potential interaction partners

• Isothermal titration calorimetry (ITC): To determine thermodynamic parameters of binding interactions

• Hydrogen-deuterium exchange mass spectrometry (HDX-MS): To identify regions of atpH involved in subunit interactions

• Cryo-electron microscopy: For structural determination of the entire ATP synthase complex with focus on atpH positioning

When interpreting interaction data, researchers should consider that ATP synthase organizations in dimers and higher oligomers may influence the interaction landscape observed in experimental settings .

What experimental approaches would best determine functional differences between Sorangium cellulosum atpH and homologs from other species?

To determine functional differences between Sorangium cellulosum atpH and homologs from other species, researchers could employ the following methodological approaches:

• Heterologous complementation studies: Express Sorangium cellulosum atpH in delta-subunit-deficient strains of model organisms (E. coli, B. subtilis) to assess functional conservation

• Chimeric protein analysis: Create fusion proteins combining domains from Sorangium cellulosum atpH with homologs from other species to identify regions responsible for species-specific functions

• In vitro reconstitution assays: Reconstitute ATP synthase complexes with either native or heterologous delta subunits to compare catalytic efficiency and assembly

• Molecular dynamics simulations: Compare predicted structural dynamics of delta subunits from different species under simulated physiological conditions

• Temperature and pH-dependent activity profiles: Characterize activity profiles across environmental conditions to identify potential adaptations to Sorangium's natural habitat

When interpreting results from these comparative studies, researchers should consider the evolutionary context and environmental adaptations of Sorangium cellulosum compared to other bacterial species.

How might post-translational modifications affect atpH function in Sorangium cellulosum?

While specific post-translational modifications (PTMs) of Sorangium cellulosum atpH are not directly addressed in the available search results, this represents an important research avenue. Potential PTMs such as phosphorylation, acetylation, or methylation could regulate ATP synthase assembly, activity, or interactions with other cellular components. The choice of expression system (yeast versus baculovirus) for recombinant production may influence the PTM profile of the resulting protein . Mass spectrometry-based proteomics approaches would be valuable for mapping the PTM landscape of native atpH isolated directly from Sorangium cellulosum under various growth conditions. Researchers interested in PTM analysis should consider:

• Comparing PTM profiles between recombinant and native protein

• Examining condition-dependent PTM changes (nutrient limitation, stress responses)

• Creating site-directed mutants at predicted PTM sites to assess functional impact

• Employing phosphoproteomic approaches to identify kinase/phosphatase networks regulating atpH

What role might atpH play in the oligomerization of ATP synthase complexes in bacterial membranes?

ATP synthase complexes can organize as dimers and higher-order oligomers, structures that contribute to both enzymatic function and membrane morphology . The potential role of atpH in mediating these oligomeric arrangements in Sorangium cellulosum represents an intriguing research question. While the search results indicate that ATP synthase oligomerization primarily involves the Fo membrane domain in mitochondrial systems , bacterial ATP synthases may employ different mechanisms. Researchers investigating this question should consider:

• Using chemical crosslinking followed by mass spectrometry to identify potential intermolecular interactions involving atpH

• Applying cryo-electron tomography to visualize ATP synthase arrangements in native membranes

• Employing fluorescence resonance energy transfer (FRET) with labeled atpH to detect proximity to subunits in adjacent ATP synthase complexes

• Creating atpH variants with mutations at potential oligomerization interfaces to assess impacts on higher-order structure formation

This research direction could provide valuable insights into the broader organizational principles of bacterial ATP synthases and how they might differ from their mitochondrial counterparts.

What are the critical considerations for designing functional assays for recombinant atpH?

When designing functional assays for recombinant Sorangium cellulosum ATP synthase subunit delta, researchers should address several critical considerations:

• Protein reconstitution: The recombinant protein should be properly reconstituted in deionized sterile water to concentrations of 0.1-1.0 mg/mL with appropriate glycerol content for stability

• Binding partner availability: Since atpH functions within the ATP synthase complex, functional assays typically require other subunits for meaningful activity assessment

• Membrane environment: For certain assays, creating a membrane-like environment using liposomes or nanodiscs may be necessary to simulate the native context

• Detecting conformational changes: Assays may need to focus on structural transitions rather than enzymatic activity, using approaches like tryptophan fluorescence to detect conformational shifts

• Temperature considerations: Given the potential temperature sensitivity of proteins from Sorangium cellulosum, assays should be performed across a temperature range to determine optimal conditions

For quality control of the assay, researchers should include appropriate positive controls (known functional homologs) and negative controls (denatured protein or mutants known to disrupt function).

What are common challenges when working with recombinant atpH and how can they be addressed?

Researchers working with recombinant Sorangium cellulosum ATP synthase subunit delta may encounter several challenges that can be addressed through specific methodological approaches:

By anticipating these challenges and implementing appropriate solutions, researchers can enhance the reliability and reproducibility of experiments utilizing recombinant atpH.

How could structural studies of Sorangium cellulosum atpH advance our understanding of bacterial ATP synthases?

Detailed structural studies of Sorangium cellulosum ATP synthase subunit delta could significantly advance our understanding of bacterial ATP synthases in several ways:

• Cryo-EM analysis: High-resolution structural determination could reveal unique features of this myxobacterial ATP synthase component compared to model organisms

• Structure-function relationships: Mapping the structural elements responsible for interaction with other subunits could enhance our understanding of ATP synthase assembly principles

• Conformational dynamics: Techniques like hydrogen-deuterium exchange mass spectrometry could reveal the dynamic structural changes that occur during the catalytic cycle

• Comparative structural biology: Comparing the structure of Sorangium cellulosum atpH with homologs from other bacteria could highlight evolutionary adaptations

• Molecular basis for oligomerization: Structural studies could reveal potential interfaces involved in higher-order ATP synthase organization

These approaches would contribute to our fundamental understanding of bacterial bioenergetics while potentially revealing unique adaptations in Sorangium cellulosum that could have biotechnological applications.

What techniques are emerging for studying the in vivo dynamics of ATP synthase subunits like atpH?

Several emerging techniques show promise for investigating the in vivo dynamics of ATP synthase subunits like atpH in Sorangium cellulosum:

• Single-molecule FRET: For measuring conformational changes and rotational dynamics of labeled atpH within the ATP synthase complex in living cells

• Super-resolution microscopy: Techniques like PALM and STORM can visualize the spatial organization of ATP synthase complexes in bacterial membranes with nanometer precision

• Time-resolved cryo-EM: For capturing different conformational states during the catalytic cycle

• In-cell NMR spectroscopy: To study structural dynamics of isotopically labeled atpH in its native cellular environment

• Proximity labeling approaches: Methods like APEX2 or BioID fused to atpH could identify transient interaction partners in vivo

• Transcriptional burst analysis: Similar to approaches used for other Sorangium genes, to understand the temporal regulation of atpH expression

These advanced techniques could provide unprecedented insights into how ATP synthase subunits function within living bacterial cells, moving beyond static structural models to dynamic understanding of this essential bioenergetic machine.