Recombinant Chloroherpeton thalassium ATP synthase subunit b (atpF)

What is Chloroherpeton thalassium ATP synthase subunit b (atpF) and why is it significant for research?

Chloroherpeton thalassium ATP synthase subunit b (atpF) is a component of the stator stalk in the ATP synthase complex of the green sulfur bacterium Chloroherpeton thalassium. This protein plays a crucial role in energy production by linking the F₁ catalytic domain to the membrane-embedded F₀ domain of ATP synthase. The significance of studying this particular subunit lies in understanding the structural and functional adaptations of ATP synthase in ancient photosynthetic bacterial lineages. ATP synthase functions as a remarkable molecular motor crucial for generating ATP through rotational catalysis driven by proton movement across membranes . The subunit b (atpF) specifically contributes to the structural stability needed for this rotational mechanism by forming part of the stator that prevents rotation of certain components while allowing others to rotate.

What expression systems are most effective for recombinant production of ATP synthase subunits?

For recombinant production of ATP synthase subunits including atpF, Escherichia coli expression systems have proven particularly effective due to their high yield, versatility, and established protocols. The pMAL expression system using T7 Express lysY/Iq E. coli cells has been successfully employed for related ATP synthase subunits . This system produces the target protein as a fusion with maltose-binding protein (MBP), which enhances solubility and facilitates purification.

When expressing potentially toxic or difficult-to-produce proteins like ATP synthase components, co-expression with chaperone proteins such as DnaK, DnaJ, and GrpE using vectors like pOFXT7KJE3 has been shown to substantially increase recombinant protein yields . This approach addresses the folding challenges often encountered with membrane-associated proteins.

A detailed comparison of expression systems is provided in Table 1:

What are the major challenges in purifying recombinant ATP synthase subunits?

Purification of recombinant ATP synthase subunits presents several challenges due to their hydrophobic nature and tendency to form inclusion bodies. The main difficulties include:

• Ensuring proper folding and avoiding aggregation, particularly for membrane-associated subunits

• Maintaining protein stability during extraction and purification steps

• Separating the target protein from host cell proteins with similar properties

• Achieving sufficient purity for structural and functional studies

A methodological approach to address these challenges includes using detergents for membrane protein solubilization, fusion tags to enhance solubility, and multi-step purification protocols. For instance, researchers have successfully employed strategies like MBP fusion tags followed by affinity chromatography with subsequent size exclusion chromatography to obtain pure ATP synthase subunits . The addition of stabilizing agents such as glycerol and specific salt concentrations in purification buffers helps maintain protein stability throughout the process.

How can molecular chaperones enhance the recombinant production of Chloroherpeton thalassium ATP synthase subunit b?

Molecular chaperones play crucial roles in enhancing recombinant production of ATP synthase subunits through multiple mechanisms. Recent research has revealed that Hsp70 chaperones not only facilitate protein folding but also specifically promote the assembly of ATP synthase complexes . For the production of Chloroherpeton thalassium ATP synthase subunit b, implementing a chaperone co-expression strategy can significantly improve yield and functionality.

The mechanism involves Hsp70 and its co-chaperones DnaJ and GrpE working together to prevent aggregation during protein synthesis and assist in proper folding. Research has shown that Hsp70 specifically monitors the assembly of ATP synthase components, including the linkage of the catalytic head to the stator where subunit b is located . Therefore, co-expression of these chaperones using plasmids like pOFXT7KJE3 alongside the atpF expression construct creates an environment conducive to proper folding and assembly.

A methodological approach would involve:

• Creating a dual-plasmid system with compatible origins of replication

• Optimizing induction conditions for both the target protein and chaperones

• Adjusting growth temperatures (typically lower temperatures of 18-25°C) to reduce aggregation

• Implementing a sequential induction strategy where chaperones are expressed first, followed by the target protein

This approach has been demonstrated to substantially increase quantities of recombinant proteins that are otherwise toxic or difficult to produce in soluble form .

What techniques are most effective for structural characterization of recombinant Chloroherpeton thalassium ATP synthase subunit b?

Structural characterization of ATP synthase subunit b requires a multi-technique approach due to its membrane-associated nature and role in the stator assembly. The most effective techniques include:

• X-ray crystallography of reconstituted complexes or stable fragments

• Cryo-electron microscopy (cryo-EM) of ATP synthase complexes containing the subunit b

• Nuclear magnetic resonance (NMR) spectroscopy for solution structure of soluble domains

• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) for identifying structural dynamics and protein-protein interaction interfaces

• Circular dichroism (CD) spectroscopy for secondary structure analysis

For functional ATP synthases, researchers have leveraged the unique properties of these molecular motors to understand structural-functional relationships. Recent studies on the electric field within ATP synthase have revealed exceptional enzymatic efficiency, with calculations showing that the enzyme operates with approximately 90% efficiency rate . Applying these advanced biophysical approaches to Chloroherpeton thalassium ATP synthase subunit b would provide insights into how this ancient version of the protein contributes to this remarkable efficiency.

How can gene synthesis and codon optimization improve expression of Chloroherpeton thalassium atpF?

Gene synthesis and codon optimization are powerful strategies for enhancing heterologous expression of challenging proteins like Chloroherpeton thalassium ATP synthase subunit b. A methodological approach involves:

• Complete gene synthesis using overlapping oligonucleotides, as demonstrated for related ATP synthase subunits where researchers constructed synthetic genes by annealing and ligating multiple overlapping oligonucleotides ranging from 24-46 bp in length .

• Codon optimization for the expression host, typically E. coli, which involves:

  • Adjusting codon usage to match tRNA availability in the host

  • Eliminating rare codons that might cause translational pausing

  • Optimizing GC content and removing sequences that might form secondary structures in mRNA

  • Eliminating internal Shine-Dalgarno-like sequences that could cause translational issues

• Incorporation of strategic restriction sites to facilitate subsequent cloning steps while avoiding changes to the amino acid sequence.

The experimental protocol typically involves:

• Designing overlapping oligonucleotides spanning the entire gene sequence

• Adding 5' phosphates to the oligonucleotides using T4 Polynucleotide Kinase with 1 mM ATP

• Annealing complementary oligonucleotides through controlled temperature ramping

• Ligating adjacent fragments using T4 DNA Ligase

• Amplifying the complete construct and verifying through sequencing

• Subcloning into the expression vector of choice

This approach has been successfully applied to ATP synthase subunit genes, resulting in significantly improved expression levels compared to direct amplification from genomic DNA .

What is the role of ATP synthase subunit b in the assembly and function of the complete ATP synthase complex?

ATP synthase subunit b plays a critical structural and functional role in the assembly and operation of the complete ATP synthase complex. Recent research has revealed new insights into this process:

The subunit b forms an essential component of the stator, connecting the F₁ catalytic domain to the membrane-embedded F₀ domain. This connection is crucial for the mechanics of ATP synthesis, as it prevents rotation of certain components while allowing others to rotate in response to proton translocation. Studies have shown that the assembly of ATP synthase follows a precise sequence, with the linkage of the catalytic head to the stator (which includes subunit b) being a key step that is monitored by molecular chaperones including Hsp70 .

The assembly process involves:

• Formation of subcomplexes within the F₁ and F₀ domains

• Assembly of the c-ring in the membrane

• Integration of subunit b as part of the stator connection

• Attachment of the catalytic head with precise alignment to enable rotational catalysis

Research by Song et al. has demonstrated that Hsp70 not only assists with protein folding but specifically monitors the linkage of the catalytic head to the stator, fulfilling a dual function in ATP synthase formation . This finding provides new insights into how complex molecular machines like ATP synthase are assembled with high precision in the cell.

The functional significance of this assembly is evident in the remarkable efficiency of ATP synthase. Molecular electrostatic potential calculations have revealed that the enzyme operates with approximately 90% efficiency, with specific electric field modifications that support proton movement and ATP formation .

How can recombinant Chloroherpeton thalassium ATP synthase subunit b be used to study evolutionary aspects of ATP synthases?

Recombinant Chloroherpeton thalassium ATP synthase subunit b offers unique opportunities for evolutionary studies of ATP synthases due to the ancient lineage of green sulfur bacteria. A methodological approach to studying evolutionary aspects would include:

• Comparative sequence analysis of atpF genes across diverse lineages, with particular attention to conserved and variable regions that might indicate functional constraints or adaptations.

• Functional complementation studies in which the Chloroherpeton thalassium atpF gene is expressed in ATP synthase-deficient mutants of model organisms to determine functional conservation.

• Chimeric protein studies where domains from Chloroherpeton thalassium ATP synthase subunit b are swapped with those from other organisms to identify functionally critical regions.

• Structural analysis comparing the ancient form with modern counterparts to trace structural evolution.

These approaches provide insights into the evolutionary trajectory of this essential molecular machine. Research on ATP synthases from anaerobic archaea has already revealed interesting evolutionary patterns, including the presence of unusual motor subunits that otherwise are only found in eukaryotic V₁V₀ ATPases . This suggests complex evolutionary relationships between ATP synthases and their related ATPases.

The study of ancient ATP synthases at low driving forces also provides insights into how these enzymes evolved to function efficiently under varying conditions . For Chloroherpeton thalassium, which occupies a unique ecological niche as an anaerobic photosynthetic bacterium, its ATP synthase may have specific adaptations for function in low-energy environments that could inform our understanding of bioenergetic evolution.

What are the optimal conditions for expression and purification of recombinant Chloroherpeton thalassium ATP synthase subunit b?

Optimizing expression and purification of recombinant Chloroherpeton thalassium ATP synthase subunit b requires careful consideration of multiple parameters. Based on successful approaches with related ATP synthase subunits, the following methodological guidelines can be implemented:

Expression Optimization:

• Selection of expression system: T7 Express lysY/Iq E. coli cells have shown good results for ATP synthase subunits

• Vector design: Fusion with solubility enhancers like MBP using vectors such as pMAL-c2x

• Growth conditions:

  • Initial growth at 37°C to OD₆₀₀ of 0.6-0.8

  • Temperature reduction to 18-25°C before induction

  • IPTG concentration of 0.1-0.5 mM for induction

  • Post-induction expression for 16-20 hours at the reduced temperature

• Co-expression with chaperones using compatible plasmids like pOFXT7KJE3 encoding DnaK, DnaJ, and GrpE to improve folding

Purification Protocol:

• Cell lysis under gentle conditions using lysozyme treatment followed by sonication

• Initial purification using affinity chromatography (amylose resin for MBP fusion proteins)

• Tag removal using specific proteases if necessary

• Secondary purification using ion exchange chromatography

• Final polishing step using size exclusion chromatography

The buffer composition is critical for maintaining protein stability throughout purification:

• Inclusion of 10-20% glycerol to stabilize the protein

• Addition of mild detergents (0.01-0.05% DDM or LDAO) for membrane-associated regions

• Maintenance of reducing conditions with 1-5 mM DTT or 2-ME

• pH optimization typically in the range of 7.0-8.0

These conditions can be systematically optimized through small-scale expression trials and stability assays to determine the ideal parameters for the specific protein.

How can functional assays be designed to evaluate the activity of recombinant Chloroherpeton thalassium ATP synthase subunit b?

• Reconstitution Assays:

  • Integration of purified recombinant subunit b into liposomes or nanodiscs

  • Combination with other purified ATP synthase components to reconstitute partial or complete complexes

  • Measurement of ATP synthesis activity in the reconstituted system

• Binding Interaction Assays:

  • Surface plasmon resonance (SPR) to quantify interactions with partner subunits

  • Isothermal titration calorimetry (ITC) for thermodynamic parameters of binding

  • Pull-down assays to verify complex formation with other ATP synthase components

• Structural Integrity Assessment:

  • Circular dichroism (CD) spectroscopy to confirm proper secondary structure formation

  • Thermal stability assays to determine melting temperature and stability

  • Limited proteolysis to identify properly folded domains

• Functional Complementation:

  • Expression of Chloroherpeton thalassium atpF in ATP synthase-deficient bacterial strains

  • Assessment of growth restoration and ATP synthesis capability

  • Measurement of proton pumping activity using pH-sensitive fluorescent probes

The structural role of subunit b in stabilizing the stator and connecting the F₁ and F₀ domains means that its function is best assessed in the context of the complete ATP synthase complex. Recent research has highlighted the importance of proper assembly for ATP synthase function, with molecular chaperones like Hsp70 playing critical roles in monitoring the linkage of the catalytic head to the stator where subunit b is located .

What mutagenesis strategies can reveal structure-function relationships in Chloroherpeton thalassium ATP synthase subunit b?

Strategic mutagenesis of Chloroherpeton thalassium ATP synthase subunit b can provide valuable insights into structure-function relationships. A methodological approach includes:

• Alanine Scanning Mutagenesis:

  • Systematic replacement of residues with alanine across the protein sequence

  • Analysis of effects on expression, stability, and function

  • Identification of critical residues for protein-protein interactions or structural integrity

• Conserved Residue Analysis:

  • Identification of highly conserved residues across species through multiple sequence alignment

  • Targeted mutagenesis of these residues to assess their functional significance

  • Correlation of conservation patterns with structural features

• Domain Swapping:

  • Replacement of entire domains or segments with corresponding regions from related species

  • Creation of chimeric proteins to identify functionally autonomous regions

  • Assessment of species-specific functional adaptations

• Cysteine Cross-linking:

  • Introduction of cysteine pairs at predicted interaction sites

  • Analysis of disulfide bond formation under oxidizing conditions

  • Mapping of subunit interaction surfaces and proximities

The experimental protocol typically involves:

• PCR-based site-directed mutagenesis of the recombinant atpF gene

• Verification of mutations by DNA sequencing

• Expression and purification of mutant proteins using the same protocols as for wild-type

• Comparative analysis of stability, binding properties, and functional contribution to ATP synthesis

These mutagenesis approaches can be particularly informative when combined with structural data or models, allowing for targeted investigation of hypothesized functional sites and interaction interfaces within the ATP synthase complex.

How can cryo-electron microscopy be optimized for studying Chloroherpeton thalassium ATP synthase complexes containing subunit b?

Cryo-electron microscopy (cryo-EM) has revolutionized the structural analysis of ATP synthase complexes, but requires optimization for specific complexes like those containing Chloroherpeton thalassium ATP synthase subunit b. A methodological approach includes:

• Sample Preparation Optimization:

  • Purification of intact ATP synthase complexes containing recombinant Chloroherpeton thalassium subunit b

  • Testing various detergents (DDM, LMNG, GDN) for solubilization while maintaining native structure

  • Screening buffer conditions for complex stability

  • Optimizing protein concentration (typically 2-5 mg/mL) for grid preparation

• Grid Preparation:

  • Systematic testing of grid types (Quantifoil, C-flat, UltrAuFoil)

  • Optimization of blotting parameters (time, force, humidity)

  • Application of thin carbon support films if necessary for preferred orientation issues

  • Use of Graphene oxide or other support films to improve particle distribution

• Data Collection Strategy:

  • Collection of tilt series to address preferred orientation problems

  • Implementation of energy filters to improve contrast

  • Optimization of electron dose to balance resolution and radiation damage

  • Use of movie mode acquisition with frame alignment to correct for beam-induced motion

• Image Processing Approaches:

  • Application of 3D classification to separate different conformational states

  • Focused refinement on the stator region containing subunit b

  • Multibody refinement to account for flexibility between domains

  • Local resolution estimation to identify regions requiring additional data

These approaches have proven successful for related ATP synthase complexes and can be adapted for the specific challenges presented by Chloroherpeton thalassium ATP synthase. The resulting structural information can provide insights into how this ancient version of ATP synthase achieves the remarkable efficiency documented in recent studies, where molecular electrostatic potential calculations have revealed approximately 90% efficiency in ATP synthesis .

How can hydrogen-deuterium exchange mass spectrometry (HDX-MS) be applied to study dynamics of Chloroherpeton thalassium ATP synthase subunit b?

Hydrogen-deuterium exchange mass spectrometry (HDX-MS) offers powerful insights into protein dynamics and conformational changes relevant to Chloroherpeton thalassium ATP synthase subunit b function. A methodological approach includes:

• Experimental Design:

  • Comparison of isolated subunit b versus complexed with partner subunits

  • Analysis under different conditions (pH, ionic strength) to mimic physiological changes

  • Time-course experiments (typically 10 seconds to 24 hours) to capture dynamics at different timescales

  • Differential analysis upon binding of interacting partners

• Sample Preparation Protocol:

  • Purification of recombinant Chloroherpeton thalassium ATP synthase subunit b with high purity

  • Initiation of exchange by dilution into D₂O buffer

  • Quenching at defined timepoints with cold acidic buffer (pH 2.5) to minimize back-exchange

  • Rapid proteolytic digestion using immobilized pepsin columns at 0°C

  • Immediate LC-MS analysis with temperature-controlled systems

• Data Analysis Strategy:

  • Peptide identification through non-deuterated control samples

  • Calculation of deuterium uptake for each peptide over time

  • Generation of uptake plots and heat maps to visualize dynamics

  • Statistical analysis to identify significant differences between conditions

  • Correlation of dynamic regions with functional domains and interaction sites

• Integration with Structural Data:

  • Mapping deuterium uptake onto available structural models

  • Identification of regions with differential solvent accessibility

  • Correlation with conformational changes associated with ATP synthase function

  • Validation through comparison with complementary techniques like molecular dynamics simulation

This technique is particularly valuable for studying ATP synthase components as it can capture the dynamic conformational changes associated with their function. Recent research has demonstrated the importance of understanding not just static structures but also the dynamic behavior of ATP synthase components in their physiological context .

How can comparative genomics inform our understanding of Chloroherpeton thalassium ATP synthase subunit b evolution?

Comparative genomics provides powerful tools for understanding the evolution of Chloroherpeton thalassium ATP synthase subunit b within the broader context of ATP synthase evolution. A methodological approach includes:

• Phylogenetic Analysis:

  • Collection of atpF sequences from diverse organisms spanning archaea, bacteria, and eukaryotes

  • Multiple sequence alignment using algorithms optimized for membrane proteins (e.g., MAFFT with L-INS-i strategy)

  • Construction of phylogenetic trees using maximum likelihood or Bayesian methods

  • Mapping of key evolutionary events and ancestral sequence reconstruction

• Synteny Analysis:

  • Examination of gene order and organization of ATP synthase operons across species

  • Identification of gene rearrangements, insertions, or deletions

  • Analysis of co-evolution patterns with other ATP synthase components

  • Correlation of genomic context with ecological niches

• Selection Pressure Analysis:

  • Calculation of dN/dS ratios to identify sites under positive or purifying selection

  • Identification of conserved domains versus variable regions

  • Correlation of selection patterns with structural features and functional requirements

  • Analysis of codon usage bias and its implications for expression efficiency

• Structural Prediction and Comparison:

  • Generation of structural models using homology modeling or AI-based prediction tools

  • Comparative analysis of predicted structural features across evolutionary diverse species

  • Identification of structural adaptations in Chloroherpeton thalassium

  • Correlation of structural conservation with functional constraints

This approach has revealed interesting evolutionary patterns in ATP synthases. For instance, research on ATP synthases from anaerobic archaea has identified unusual motor subunits that are otherwise only found in eukaryotic V₁V₀ ATPases, suggesting complex evolutionary relationships between these related enzyme families . For Chloroherpeton thalassium, which represents an ancient bacterial lineage, comparative genomics can provide insights into the early evolution of bacterial ATP synthases and their adaptation to specific ecological niches.

What computational approaches can predict interaction interfaces between Chloroherpeton thalassium ATP synthase subunit b and other components?

Predicting interaction interfaces between ATP synthase subunit b and other components of the complex can be achieved through various computational approaches:

• Homology-Based Interface Prediction:

  • Construction of structural models based on homologous ATP synthase structures

  • Mapping of known interaction sites from related structures

  • Analysis of conservation patterns at predicted interfaces

  • Validation through experimental approaches like cross-linking

• Protein-Protein Docking:

  • Generation of docking models between subunit b and partner subunits

  • Scoring and ranking of potential interaction modes

  • Refinement of top-scoring models through energy minimization

  • Clustering analysis to identify consensus binding modes

• Coevolution Analysis:

  • Identification of coevolving residue pairs using methods like Direct Coupling Analysis

  • Statistical validation of predicted contacts

  • Construction of contact maps to guide structural modeling

  • Integration with sparse experimental constraints

• Molecular Dynamics Simulations:

  • Simulation of subunit b in complex with partner proteins

  • Analysis of stable contacts during simulation trajectories

  • Calculation of binding energies and identification of key interacting residues

  • Investigation of conformational dynamics at interfaces

These computational approaches are particularly valuable for understanding how ATP synthase achieves its remarkable efficiency. Recent studies have shown that the enzyme operates with approximately 90% efficiency, with specific electric field properties that support proton movement and ATP formation . Computational modeling of interaction interfaces can provide insights into how this efficiency is achieved through precise molecular interactions.

The predicted interfaces can be validated and refined through targeted experimental approaches such as site-directed mutagenesis of interface residues, cross-linking studies, or hydrogen-deuterium exchange mass spectrometry.

How can recombinant Chloroherpeton thalassium ATP synthase components contribute to bioenergetic studies?

Recombinant Chloroherpeton thalassium ATP synthase components, including subunit b (atpF), offer unique opportunities for bioenergetic studies due to the ancient evolutionary position of this organism. A methodological approach includes:

• Comparative Bioenergetics:

  • Reconstitution of ATP synthase complexes with components from different species including Chloroherpeton thalassium

  • Measurement of ATP synthesis rates under varying proton motive force conditions

  • Analysis of efficiency and kinetic parameters across evolutionary diverse ATP synthases

  • Investigation of adaptations to different environmental conditions

• Structure-Based Bioenergetic Analysis:

  • Correlation of structural features with energy conversion efficiency

  • Investigation of the electric field properties within the ATP synthase complex

  • Analysis of how structural differences influence proton translocation pathways

  • Experimental validation through site-directed mutagenesis of key residues

• Single-Molecule Biophysics:

  • Attachment of fluorescent or gold nanoparticle probes to specific subunits

  • Real-time observation of rotational dynamics using total internal reflection microscopy

  • Measurement of torque generation and mechanical work

  • Correlation of structural features with mechanical properties

• Synthetic Biology Applications:

  • Engineering of hybrid ATP synthases with components from different species

  • Design of ATP synthases with altered ion specificity or improved efficiency

  • Development of minimal ATP synthase systems for biotechnological applications

  • Creation of ATP synthase-based nanomotors or energy conversion devices

These approaches can provide insights into the fundamental principles of biological energy conversion. Recent research has revealed that ATP synthase has exceptional enzymatic efficiency, with molecular electrostatic potential calculations demonstrating approximately 90% efficiency in energy conversion . Studying ancient versions of this enzyme, such as that from Chloroherpeton thalassium, can reveal how this remarkable efficiency evolved and potentially inspire bio-inspired energy technologies.

What are the implications of ATP synthase assembly mechanisms for understanding mitochondrial diseases?

Though Chloroherpeton thalassium is a bacterial species, studies of its ATP synthase assembly can provide valuable insights relevant to mitochondrial diseases in humans. A methodological approach includes:

• Comparative Analysis of Assembly Mechanisms:

  • Investigation of conserved assembly factors between bacteria and mitochondria

  • Identification of species-specific assembly pathways versus universal mechanisms

  • Analysis of how subunit b contributes to complex stability across species

  • Translation of findings from bacterial systems to mitochondrial disease contexts

• Molecular Chaperone Functions:

  • Study of how molecular chaperones like Hsp70 assist in ATP synthase assembly

  • Investigation of the dual role of Hsp70 in protein folding and complex assembly

  • Analysis of how defects in chaperone function affect ATP synthase biogenesis

  • Correlation with known mitochondrial disease mechanisms

Recent research has revealed that Hsp70 not only acts as a "folding helper" of proteins in mitochondria but also specifically promotes the assembly of ATP synthase . This dual function involves monitoring the assembly of the catalytic head and controlling the linkage of the head to the stator, where subunit b is located . Defects in these processes can lead to impaired ATP synthase assembly and function, which has been linked to various human diseases.

The implications for human health are significant, as defects in ATP synthase have been associated with numerous pathological conditions, including cardiovascular diseases, obesity, type II diabetes, neurodegenerative disorders, and cancer . Understanding the fundamental assembly mechanisms through studies of diverse ATP synthases, including ancient versions like that from Chloroherpeton thalassium, can provide insights into potential therapeutic approaches for mitochondrial diseases.

What are the best protocols for gene synthesis and cloning of Chloroherpeton thalassium atpF?

The optimal protocol for gene synthesis and cloning of Chloroherpeton thalassium atpF involves a stepwise approach that balances efficiency, accuracy, and cost-effectiveness:

• Gene Design Strategy:

  • Retrieval of the atpF sequence from genome databases

  • Codon optimization for the expression host (typically E. coli)

  • Addition of appropriate restriction sites for subsequent cloning

  • Removal of internal restriction sites while maintaining the amino acid sequence

  • Design of overlapping oligonucleotides spanning the entire gene

• Gene Synthesis Protocol:

  • Synthesis of overlapping oligonucleotides (typically 24-46 bp in length)

  • Phosphorylation of individual oligonucleotides using T4 Polynucleotide Kinase with 1 mM ATP

  • Annealing of complementary oligonucleotides by heating to 80°C and cooling to 20°C over 60 minutes

  • Ligation of adjacent fragments using T4 DNA Ligase

  • PCR amplification of the full-length gene

  • Gel purification of the correct-sized product

• Cloning Strategy:

  • Digestion of the synthetic gene and destination vector with appropriate restriction enzymes

  • Ligation into expression vector (e.g., pMAL-c2x for MBP fusion)

  • Transformation into cloning strain (e.g., DH5α)

  • Colony PCR and restriction analysis to identify positive clones

  • Verification by DNA sequencing

  • Transformation into expression strain (e.g., T7 Express lysY/Iq)

This stepwise approach has been successfully applied to ATP synthase subunits, as demonstrated in the research on recombinant production of ATP synthase subunit c . The methodology can be readily adapted for Chloroherpeton thalassium atpF, with appropriate modifications based on the specific sequence characteristics of this gene.

What are the critical quality control measures for evaluating recombinant Chloroherpeton thalassium ATP synthase subunit b?

Comprehensive quality control of recombinant Chloroherpeton thalassium ATP synthase subunit b requires multiple analytical approaches targeting different aspects of protein quality:

• Purity Assessment:

  • SDS-PAGE analysis with Coomassie and silver staining

  • Size exclusion chromatography to detect aggregates or degradation products

  • Mass spectrometry for accurate mass determination and contaminant identification

  • Analytical ultracentrifugation for homogeneity analysis

• Structural Integrity Verification:

  • Circular dichroism (CD) spectroscopy to confirm secondary structure content

  • Fluorescence spectroscopy to assess tertiary structure

  • Dynamic light scattering to evaluate size distribution and aggregation state

  • Limited proteolysis to verify proper folding through digestion pattern analysis

• Functional Validation:

  • Binding assays with partner subunits using SPR or ITC

  • Assembly into larger complexes verified by native PAGE or blue native PAGE

  • Contribution to ATP synthesis activity in reconstituted systems

  • Stability studies under various conditions to assess robustness

• Identity Confirmation:

  • Western blotting with specific antibodies

  • Peptide mass fingerprinting using tryptic digestion and mass spectrometry

  • N-terminal sequencing to confirm the correct start of the protein

  • If applicable, activity of fusion tags (e.g., MBP binding to amylose)