Recombinant Photobacterium profundum Probable intracellular septation protein A (PBPRA2506)

What is Photobacterium profundum PBPRA2506 and what is its basic function?

PBPRA2506 is a probable intracellular septation protein A found in Photobacterium profundum, specifically strain SS9, a deep-sea piezophilic bacterium originally isolated from the Sulu Sea. The protein is annotated with UniProt ID Q6LP88 . As an intracellular septation protein, PBPRA2506 is believed to be involved in cell division processes, particularly in the formation of the septum during bacterial cell division. The full amino acid sequence of PBPRA2506 consists of 179 amino acids, with the expression region spanning positions 1-179 . This membrane-associated protein likely plays a crucial role in the adaptation of P. profundum to high-pressure environments.

What are the optimal storage conditions for recombinant PBPRA2506?

For optimal stability and activity preservation of recombinant PBPRA2506, the protein should be stored in Tris-based buffer with 50% glycerol at -20°C for routine storage . For extended preservation, storage at -80°C is recommended. To minimize protein degradation, repeated freeze-thaw cycles should be avoided. Working aliquots can be maintained at 4°C for up to one week . These storage recommendations are based on standard protein preservation protocols and the specific characteristics of this recombinant protein preparation.

What is the significance of studying Photobacterium profundum proteins in pressure adaptation research?

Photobacterium profundum SS9 serves as an excellent model organism for studying piezophily (adaptation to high pressure) because it can grow under a wide range of pressures while exhibiting optimal growth at 28 MPa and 15-16°C . Unlike many deep-sea bacteria, P. profundum can be cultured at atmospheric pressure, allowing for easier genetic manipulation and laboratory study . This makes it invaluable for investigating pressure-responsive cellular processes and the molecular mechanisms of deep-sea adaptation. Proteomics studies have revealed distinct protein expression patterns under different pressure conditions, indicating complex adaptive responses to hydrostatic pressure . By studying specific proteins like PBPRA2506, researchers can gain insights into how cellular processes such as cell division are modified to function optimally under high pressure conditions.

What are the recommended protocols for expressing and purifying recombinant PBPRA2506?

Based on established protocols for similar P. profundum proteins, recombinant PBPRA2506 expression should be approached using the following methodology:

• Expression System Selection: Use an E. coli expression system with a pET vector containing an appropriate tag (6xHis is commonly used) for purification purposes.

• Culture Conditions: Transform the expression vector into E. coli BL21(DE3) or similar strain. Culture at 37°C in LB medium supplemented with appropriate antibiotics until OD600 reaches 0.6-0.8.

• Induction: Induce protein expression with 0.5-1.0 mM IPTG, then lower the temperature to 16-18°C for overnight expression to enhance proper folding.

• Cell Harvesting and Lysis: Harvest cells by centrifugation (4,000×g, 15 min, 4°C) and lyse using sonication in a buffer containing 50 mM Tris-HCl pH 7.5, 300 mM NaCl, 10% glycerol, and protease inhibitors.

• Purification: Purify using affinity chromatography (Ni-NTA for His-tagged protein), followed by size exclusion chromatography for highest purity.

• Quality Control: Verify purity by SDS-PAGE and confirm identity using Western blot or mass spectrometry.

• Storage: Store in Tris-based buffer with 50% glycerol at -20°C or -80°C for extended storage .

This methodology is adapted from protocols used for other membrane-associated bacterial proteins and tailored to the specific characteristics of PBPRA2506.

How can researchers effectively study the membrane localization and topology of PBPRA2506?

To investigate the membrane localization and topology of PBPRA2506, researchers should implement a multi-method approach:

• Computational Prediction: Begin with bioinformatic analysis using tools like TMHMM, CELLO, and pSORT to predict transmembrane domains and cellular localization . These predictions suggest PBPRA2506 is likely membrane-associated.

• Fractionation Studies: Perform cellular fractionation to separate cytoplasmic, periplasmic, and membrane fractions, followed by Western blot analysis to determine which fraction contains PBPRA2506.

• Fluorescent Protein Fusions: Create GFP-PBPRA2506 fusion constructs to visualize localization in living cells using fluorescence microscopy. The NanoOrange protein staining method used for P. profundum in other studies can be adapted for this purpose .

• Protease Accessibility Assays: Use limited proteolysis on intact cells, spheroplasts, and membrane vesicles to determine which portions of the protein are accessible from different cellular compartments.

• Cysteine Scanning Mutagenesis: Introduce cysteine residues at various positions and use membrane-impermeable thiol-reactive reagents to map exposed regions.

• Electron Microscopy: Employ immunogold labeling with anti-PBPRA2506 antibodies for high-resolution localization using electron microscopy.

When implementing these approaches, researchers should consider performing experiments at both atmospheric pressure (0.1 MPa) and high pressure (28 MPa) to determine if pressure affects the protein's localization or topology.

What techniques are available for studying the effect of hydrostatic pressure on PBPRA2506 function?

Several specialized techniques can be employed to study PBPRA2506 function under various pressure conditions:

• High-Pressure Growth Systems: Culture P. profundum in pressure vessels at different pressures (0.1-30 MPa) using sealed polyethylene transfer pipettes filled with appropriate media . Compare growth rates and protein expression levels across pressure conditions.

• High-Pressure Spectroscopy: Employ high-pressure chambers compatible with spectroscopic techniques (CD, fluorescence) to study pressure-induced conformational changes in purified PBPRA2506.

• Pressure-Regulated Expression Systems: Develop systems where PBPRA2506 expression can be controlled while cells are maintained under pressure to study immediate effects of the protein on cellular physiology.

• Genetic Complementation Studies: Create PBPRA2506 deletion mutants and test growth/phenotype at various pressures. Complement with wild-type or mutated variants to identify critical functional domains and residues.

• Comparative Proteomics: Apply label-free quantitative proteomics to compare protein interaction networks at different pressures, as described in previous studies with P. profundum :

• High-Pressure Microscopy: Utilize high-pressure microscopy systems like the HPDS high-pressure cell described in the literature to visualize cells expressing fluorescently tagged PBPRA2506 under pressure.

How does PBPRA2506 expression change in response to varying pressure conditions?

While specific expression data for PBPRA2506 is not directly provided in the search results, we can infer likely expression patterns based on proteomic studies of P. profundum under different pressure conditions . These studies reveal that pressure acts as a significant regulatory factor for protein expression in this organism.

Based on related findings, we can propose that:

• Pressure-Dependent Regulation: PBPRA2506 expression is likely regulated in response to hydrostatic pressure, similar to other proteins involved in cellular processes affected by pressure.

• Expression Pattern Hypothesis: Given its predicted role in cell division, PBPRA2506 may show increased expression at the organism's optimal growth pressure (28 MPa) to facilitate proper cell division under those conditions.

• Integration with Cellular Processes: The regulation of PBPRA2506 would be integrated with other pressure-responsive cellular systems. Proteomic analyses have shown that P. profundum upregulates different metabolic pathways at different pressures - glycolysis/gluconeogenesis at high pressure (28 MPa) and oxidative phosphorylation at atmospheric pressure (0.1 MPa) .

• Regulatory Mechanisms: Expression changes could occur through direct physical effects of pressure on gene expression machinery or through dedicated pressure-sensing regulatory systems, as suggested by studies on other pressure-responsive genes in P. profundum .

Experimental validation through targeted proteomics or Western blot analysis would be needed to confirm the specific expression pattern of PBPRA2506 across pressure gradients.

What protein-protein interactions are predicted or known for PBPRA2506?

As a probable intracellular septation protein, PBPRA2506 likely participates in a network of interactions with other cell division proteins. While specific interaction data for PBPRA2506 is not provided in the search results, we can make informed predictions based on knowledge of bacterial cell division processes:

• Divisome Components: PBPRA2506 likely interacts with core components of the bacterial divisome, including FtsZ (the bacterial tubulin homolog that forms the contractile ring), FtsA, and ZipA.

• Peptidoglycan Synthesis Machinery: As septation involves new cell wall formation, PBPRA2506 may interact with proteins involved in peptidoglycan synthesis, such as penicillin-binding proteins (PBPs).

• Regulatory Proteins: Interactions with regulatory proteins that coordinate cell division with cell growth and environmental conditions (including pressure changes) are probable.

• Pressure-Related Adaptation: The interaction network may be dynamically adjusted under different pressure conditions, potentially involving chaperones like DnaK (PBPRA0697) and GroEL (PBPRA3387), which have been shown to be pressure-regulated in P. profundum .

To experimentally validate these predicted interactions, researchers should consider:

• Bacterial two-hybrid or split-GFP complementation assays

• Co-immunoprecipitation followed by mass spectrometry

• Crosslinking studies coupled with proteomics

• Fluorescence resonance energy transfer (FRET) between tagged proteins

These experiments should ideally be conducted under both atmospheric and high-pressure conditions to identify pressure-dependent changes in the interaction network.

How can PBPRA2506 be utilized in synthetic biology applications for deep-sea biotechnology?

PBPRA2506 and other pressure-adapted proteins from P. profundum represent valuable components for developing synthetic biology systems functioning in high-pressure environments:

• Pressure-Tolerant Cell Division Module: Incorporating PBPRA2506 into non-piezophilic organisms could potentially enhance their ability to divide correctly under high pressure, which would be valuable for engineered organisms designed for deep-sea applications.

• Pressure-Sensing Biosystems: By coupling PBPRA2506 or its regulatory elements to reporter systems, researchers could develop biological pressure sensors for deep-sea monitoring applications.

• Bioremediation at Depth: Engineered organisms containing pressure-adapted cell division machinery could be developed for bioremediation of deep-sea oil spills or other contaminants.

• Pressure-Regulated Gene Expression Systems: The regulatory elements controlling PBPRA2506 expression could be repurposed to create synthetic gene circuits that respond to pressure changes, allowing for controlled protein expression at specific ocean depths.

• Biomaterial Production: Understanding how PBPRA2506 contributes to cell wall formation under pressure could inform the development of novel biomaterials with enhanced pressure resistance properties.

Implementation would require detailed characterization of PBPRA2506's function, regulation, and interactions, followed by modular engineering approaches to integrate these components into synthetic systems with predictable behaviors under various pressure conditions.

What approaches can be used to investigate the evolutionary adaptation of PBPRA2506 in pressure-adapted organisms?

Investigating the evolutionary adaptation of PBPRA2506 requires a multi-faceted approach combining comparative genomics, molecular evolution analyses, and functional studies:

• Phylogenetic Analysis: Construct phylogenetic trees using PBPRA2506 homologs from bacteria inhabiting different depth zones to trace its evolutionary history and identify convergent adaptations to high pressure.

• Selective Pressure Analysis: Calculate dN/dS ratios (non-synonymous to synonymous substitution rates) to identify positions under positive selection, which may indicate adaptive sites crucial for pressure adaptation.

• Ancestral Sequence Reconstruction: Computationally reconstruct ancestral sequences of PBPRA2506 to understand the evolutionary trajectory of pressure adaptation.

• Domain Architecture Comparison: Compare the domain organization of PBPRA2506 homologs from shallow-water and deep-sea bacteria to identify structural features associated with pressure adaptation.

• Horizontal Gene Transfer Analysis: Investigate whether pressure-adaptive features of PBPRA2506 may have been acquired through horizontal gene transfer events.

• Functional Validation: Express reconstructed ancestral sequences or homologs from different depth zones in P. profundum deletion mutants to test functionality under various pressure conditions.

• Structural Comparison: Use comparative modeling to identify structural differences between PBPRA2506 homologs that may contribute to pressure adaptation.

This evolutionary framework would provide insights into how nature has engineered proteins to function under extreme pressure conditions, potentially revealing design principles for pressure-resistant proteins.

How does PBPRA2506 function compare between mesophilic, psychrophilic, and piezophilic bacterial species?

A comparative analysis of PBPRA2506 homologs across bacteria adapted to different environmental conditions would reveal important insights into functional adaptation:

Key differences likely include:

• Amino Acid Composition: Piezophilic variants typically contain fewer large, bulky hydrophobic residues and more small residues that reduce protein volume under pressure.

• Structural Flexibility: Different flexibility patterns optimized for their respective environments - increased flexibility in cold-adapted variants and specific pressure-sensitive flexible regions in piezophilic variants.

• Electrostatic Interactions: Potentially more salt bridges and electrostatic interactions in piezophilic variants to stabilize the protein under pressure.

• Hydration Properties: Differences in surface hydrophobicity and charge distribution affecting water interactions under pressure.

• Functional Adaptation: Potentially different kinetic parameters (Km, kcat) optimized for efficiency under respective environmental conditions.

Experimental approaches to investigate these differences would include heterologous expression of PBPRA2506 homologs followed by functional assays under varying temperature and pressure conditions, structural studies using techniques like hydrogen-deuterium exchange mass spectrometry, and in silico molecular dynamics simulations under different pressure conditions.

What are the main challenges in expressing and purifying functional PBPRA2506 for in vitro studies?

Researchers working with PBPRA2506 face several technical challenges that require specialized approaches:

• Membrane Protein Solubility: As a probable membrane-associated protein, PBPRA2506 may have hydrophobic domains that complicate expression and purification in soluble form. Strategies to address this include:

  • Using specialized detergents or amphipols for extraction and stabilization

  • Fusion with solubility-enhancing tags (MBP, SUMO)

  • Expression as truncated constructs of soluble domains

  • Employing membrane-mimetic systems like nanodiscs or liposomes for functional studies

• Pressure-Adaptive Features: The protein's adaptation to high pressure may result in instability at atmospheric pressure, requiring:

  • Expression at lower temperatures (16°C)

  • Inclusion of stabilizing agents in buffers

  • Rapid purification protocols to minimize time at atmospheric pressure

  • Consideration of high-pressure purification methods

• Functional Validation: Confirming that purified PBPRA2506 retains its native function is challenging and may require:

  • Development of specific activity assays

  • Reconstitution in membrane systems

  • Co-purification with interaction partners

  • High-pressure functional assays

• Structural Studies: Obtaining structural information presents additional challenges:

  • Crystallization of membrane proteins is notoriously difficult

  • Cryo-EM may require specialized detergent screening

  • NMR studies may require extensive optimization for membrane proteins

Each of these challenges requires methodological adaptations, and researchers should be prepared to test multiple conditions and approaches to achieve successful expression and purification of functional PBPRA2506.

How can researchers overcome the challenges of studying PBPRA2506 function under high-pressure conditions?

Studying protein function under high pressure requires specialized equipment and methodologies:

• High-Pressure Equipment Adaptation: Standard laboratory equipment must be modified for high-pressure studies:

  • Pressure-resistant vessels for cell culture (as described in references )

  • Specialized high-pressure chambers for biochemical assays

  • Pressure-compatible spectroscopy cells

  • High-pressure microscopy systems

• Experimental Design Considerations:

  • Include proper controls at atmospheric pressure

  • Implement step-wise pressure increases to identify threshold effects

  • Consider time as a variable (acute vs. chronic pressure exposure)

  • Account for pressure effects on other components in the system (buffers, substrates)

• In vitro Functional Assays:

  • Develop assays compatible with high-pressure equipment

  • Consider fluorescence-based assays that can be monitored through pressure chamber windows

  • Establish baseline pressure effects on assay components

• Genetic Approaches:

  • Use pressure-resistant reporter systems for in vivo studies

  • Develop pressure-cycling protocols that allow genetic manipulation at atmospheric pressure followed by phenotypic analysis under pressure

  • Consider comparative studies with homologs from non-piezophilic organisms

• Data Collection and Analysis:

  • Implement remote or automated data collection systems for extended high-pressure experiments

  • Develop analytical methods that account for pressure effects on measurement parameters

  • Use computational models to bridge gaps in experimental capabilities

By addressing these challenges methodically, researchers can develop robust approaches for studying PBPRA2506 function across pressure gradients relevant to its native deep-sea environment.

What controls and validation steps should be implemented when studying pressure effects on PBPRA2506?

Rigorous experimental design for pressure studies on PBPRA2506 should include:

• Experimental Controls:

  • Positive controls: Include well-characterized pressure-responsive proteins (e.g., DnaK and GroEL ) in parallel experiments

  • Negative controls: Include proteins known to be pressure-insensitive

  • Wild-type vs. mutant comparisons: Test PBPRA2506 variants with specific mutations

  • Pressure gradients: Test multiple pressure points (not just atmospheric vs. high pressure)

• Validation Approaches:

  • Orthogonal methods: Confirm findings using multiple independent techniques

  • Reversibility testing: Verify whether pressure effects are reversible upon decompression

  • Time-course studies: Distinguish between immediate physical effects and adaptive responses

  • In vitro - in vivo correlation: Relate biochemical findings to cellular phenotypes

• Statistical Considerations:

  • Biological replicates: Minimum of three independent experiments

  • Technical replicates: Multiple measurements within each experiment

  • Appropriate statistical tests: Consider non-linear responses to pressure

  • Power analysis: Ensure sufficient sample size for detecting pressure effects

• Pressure Application Protocols:

  • Rate of pressurization: Control and report the rate of pressure increase/decrease

  • Pressure stability: Monitor pressure throughout experiments

  • Temperature control: Maintain constant temperature during pressure experiments

  • Medium composition: Account for pressure effects on pH and gas solubility

• Data Reporting Standards:

  • Detailed methods reporting: Include all pressure parameters and equipment specifications

  • Raw data accessibility: Make primary data available for reanalysis

  • Comprehensive controls reporting: Include all control data in publications

  • Limitations acknowledgment: Discuss technical constraints and their potential impact

Following these guidelines will enhance the reliability and reproducibility of pressure studies on PBPRA2506, facilitating comparison across different research groups and experimental systems.

What emerging technologies could advance our understanding of PBPRA2506 function and regulation?

Several cutting-edge technologies hold promise for deepening our understanding of PBPRA2506:

• Cryo-Electron Tomography under Pressure: Emerging capabilities to perform cryo-ET under variable pressure conditions could allow visualization of PBPRA2506 in its native cellular context at relevant pressures.

• Single-Molecule Studies under Pressure: Adapting single-molecule techniques (FRET, force spectroscopy) to high-pressure conditions could reveal dynamic aspects of PBPRA2506 function and interactions.

• Microfluidic Pressure Systems: Developing microfluidic platforms capable of rapid pressure cycling would enable high-throughput studies of pressure effects on PBPRA2506 and its interaction partners.

• In-Cell NMR under Pressure: Adapting in-cell NMR techniques for pressure studies could provide atomic-level information about PBPRA2506 structure and dynamics in living cells.

• CRISPR-Based Approaches: Applying CRISPR technologies for precise genome editing in P. profundum would facilitate more sophisticated genetic studies of PBPRA2506 function.

• Computational Approaches:

  • Advanced molecular dynamics simulations under pressure

  • Machine learning approaches to predict pressure effects on protein function

  • Systems biology modeling of PBPRA2506 within pressure-responsive networks

• Synthetic Biology Tools: Development of pressure-responsive genetic circuits and biosensors would enable more sophisticated studies of PBPRA2506 regulation.

• Multi-Omics Integration: Combining proteomics, transcriptomics, and metabolomics data across pressure gradients could position PBPRA2506 within global cellular response networks.

These emerging technologies would complement existing approaches and potentially reveal new aspects of PBPRA2506 biology that are inaccessible with current methods.

How might research on PBPRA2506 contribute to our understanding of bacterial adaptation to extreme environments?

Research on PBPRA2506 has broader implications for understanding bacterial adaptation to extreme environments:

• Mechanistic Insights into Pressure Adaptation: Detailed characterization of PBPRA2506 would reveal specific molecular mechanisms that enable cellular processes to function under high pressure, potentially identifying common principles applicable to other pressure-adapted proteins.

• Evolutionary Perspectives: Comparative studies of PBPRA2506 across bacterial species from different depth zones could illuminate evolutionary pathways to pressure adaptation, revealing whether convergent or divergent evolution predominates in piezophilic adaptation.

• Cellular Process Integration: Understanding how PBPRA2506 functions within the cell division machinery would demonstrate how essential cellular processes are modified for extreme environments while maintaining core functionality.

• Multi-Stressor Adaptation: P. profundum inhabits environments with both high pressure and low temperature, making PBPRA2506 valuable for studying how proteins adapt to multiple simultaneous stressors.

• Biotechnological Applications: Insights from PBPRA2506 could inform the development of pressure-resistant enzymes and organisms for biotechnological applications in high-pressure environments.

• Astrobiology Relevance: Understanding pressure adaptation mechanisms has implications for the search for life in high-pressure extraterrestrial environments, such as subsurface oceans on icy moons.

• Fundamental Biophysics: Studies of pressure effects on PBPRA2506 structure and function would contribute to our fundamental understanding of protein-solvent interactions under extreme conditions.

By positioning PBPRA2506 research within these broader contexts, researchers can maximize its impact on our understanding of life's adaptation to extreme environments.

What are the potential applications of understanding PBPRA2506 function for biotechnology and astrobiology?

Research on PBPRA2506 opens several applied research avenues:

• Deep-Sea Biotechnology Applications:

  • Development of pressure-resistant production strains for deep-sea bioremediation

  • Engineering of microorganisms for resource recovery from deep-sea environments

  • Creation of pressure-stable enzymes for industrial bioprocessing under pressure

• Biomedical Applications:

  • Insights into bacterial cell division under pressure could inform antimicrobial strategies

  • Understanding of pressure-resistant proteins could benefit high-pressure processing in the food and pharmaceutical industries

  • Potential applications in protein stabilization for therapeutics

• Astrobiology Implications:

  • Models for potential adaptation mechanisms in high-pressure extraterrestrial environments

  • Biosignature identification strategies for high-pressure environments

  • Design parameters for instruments to detect life in high-pressure extraterrestrial settings

• Synthetic Biology Tools:

  • Pressure-responsive genetic switches derived from PBPRA2506 regulatory elements

  • Cellular pressure sensors based on PBPRA2506 conformational changes

  • Pressure-stable cellular chassis for synthetic biology applications

• Materials Science Applications:

  • Biomimetic pressure-resistant materials inspired by structural features of PBPRA2506

  • Pressure-responsive biomaterials utilizing principles derived from PBPRA2506 function

• Environmental Monitoring:

  • Biosensors for deep-sea environmental monitoring based on PBPRA2506 or its regulatory elements

  • Indicator organisms for pressure disturbances in deep-sea environments

These applications represent the translational potential of fundamental research on PBPRA2506, highlighting the value of studying adaptations to extreme environments for addressing practical challenges in biotechnology and astrobiology.