Recombinant Azotobacter vinelandii UPF0761 membrane protein Avin_36810 (Avin_36810)

What is Avin_36810 and what organism does it come from?

Avin_36810 is classified as a UPF0761 membrane protein that originates from the soil bacterium Azotobacter vinelandii . The UPF0761 designation indicates it belongs to a family of uncharacterized protein function, meaning its precise biological role remains to be fully elucidated through ongoing research. Azotobacter vinelandii is a gram-negative, aerobic soil bacterium known for its nitrogen-fixing capabilities and ability to synthesize polymers such as poly-β-hydroxybutyrate (PHB), which has applications in biodegradable plastic production . The protein is identified in protein databases with the UniProt ID C1DRV2, providing researchers with a standardized reference point for comparative analyses across protein databases . Understanding this protein's basic characteristics forms the foundation for more complex investigations into its structure and function.

What is the complete amino acid sequence and structural properties of Avin_36810?

The complete amino acid sequence of Avin_36810 consists of 408 amino acids with the following sequence: MRQRFVDSLDFWRYLFERFLADQGPKSAAALTYTALFAVVPIMTLIFVVLSVVPDFQGIGEQIQGFIFRNFVPSSGAVLQDYLRTFIEQARHLTWLGVGVLMVTALLMLMTVEHTFNTIWRVRRPRRGLSSFLLHWAILSLGPLLLGTGFALSTYITSLSLVSDPYALAGARMLLKVMPLLFSTAAFTLLYVAVPNTAVPLRHALLGGLFAAVLFEAAKGLFGLYVALFPTYQLIYGAFAAVPLFLLWMYLSWMIVLLGAELVCNLSASRRWRRNPLPRLLVLLGVLRVFHQSQQSGQAVRQPDLQRAGWALPDSVWDEMLDFLEREQLICRVSDGGWVLCRDLNRYSLESLLSRSPWPLPHLDQLPESLDEPWFPALRSALERLQRERAALFGDSLANWLQPPLSEP . Analysis of this sequence reveals hydrophobic regions characteristic of membrane proteins, suggesting multiple transmembrane domains. The protein's membrane localization is indicated by both its classification and sequence properties, with hydrophobic stretches forming transmembrane helices that anchor it within the cell membrane. Though detailed three-dimensional structural information remains limited, computational predictions based on the amino acid sequence suggest multiple transmembrane domains with intracellular and extracellular regions that may participate in signaling or transport functions. This structural information provides essential context for designing experiments to investigate protein function and interactions.

What expression systems are available for producing recombinant Avin_36810?

Recombinant Avin_36810 has been successfully expressed in Escherichia coli expression systems, as evidenced by commercially available products . The available recombinant protein preparation utilizes a His-tag fusion at the N-terminal, facilitating purification through affinity chromatography methods . While E. coli remains the most documented expression system for this protein, researchers should consider that membrane proteins often present expression challenges in bacterial systems due to toxicity, insolubility, or improper folding. Alternative expression systems that might be explored include yeast (Pichia pastoris or Saccharomyces cerevisiae), insect cells (using baculovirus expression vectors), or mammalian cell cultures for instances where mammalian-specific post-translational modifications might be required. Each system offers distinct advantages in terms of protein yield, folding correctness, and post-translational modifications. The choice of expression system should be guided by the specific experimental requirements, including the need for functional activity versus structural studies.

What purification strategies are most effective for recombinant Avin_36810?

Purification of recombinant Avin_36810 typically employs affinity chromatography utilizing the N-terminal His-tag that is incorporated into recombinant versions of the protein . The purification process likely involves cell lysis, membrane fraction isolation, detergent solubilization of membrane proteins, and affinity chromatography using nickel or cobalt resins that selectively bind the His-tagged protein. Based on standard protocols for membrane proteins, a multi-step purification strategy would be recommended, beginning with crude fractionation through differential centrifugation to isolate membrane fractions, followed by solubilization using detergents such as n-dodecyl-β-D-maltoside (DDM) or n-octyl-β-D-glucopyranoside (OG) that maintain protein structure while extracting it from the lipid bilayer. Following affinity chromatography, size exclusion chromatography can be employed as a polishing step to achieve higher purity, with commercial preparations reporting purity levels greater than 90% as determined by SDS-PAGE analysis . For functional studies, researchers should carefully select detergents that preserve native protein conformation and consider reconstituting the purified protein into liposomes or nanodiscs to maintain a membrane-like environment.

What are the optimal storage conditions for maintaining Avin_36810 stability and activity?

According to product documentation, purified recombinant Avin_36810 is typically provided as a lyophilized powder, requiring careful handling and storage to maintain stability and activity . The recommended storage conditions include keeping the lyophilized protein at -20°C to -80°C, with aliquoting necessary for multiple use scenarios to avoid repeated freeze-thaw cycles that can damage protein structure . When reconstituted, working aliquots can be stored at 4°C for up to one week, but longer-term storage requires re-freezing with cryoprotectants . The reconstitution process should involve using deionized sterile water to achieve a concentration of 0.1-1.0 mg/mL, with the addition of 5-50% glycerol (final concentration) recommended for long-term storage stability, with 50% being the default recommendation . These precautions are particularly important for membrane proteins, which are often less stable than soluble proteins due to their hydrophobic surfaces that can promote aggregation. Researchers should verify protein integrity after storage through activity assays or structural analyses appropriate to their experimental goals before proceeding with critical experiments.

What analytical techniques are most suitable for characterizing Avin_36810 structure and function?

Characterization of Avin_36810 structure and function requires a multi-technique approach due to the challenges associated with membrane protein analysis. For structural characterization, techniques such as circular dichroism (CD) spectroscopy can provide information about secondary structure composition, while more detailed structural information might require X-ray crystallography or cryo-electron microscopy, though these typically require significant quantities of highly purified, stable protein. Functional characterization might employ techniques specific to membrane proteins, including liposome reconstitution assays to study transport or signaling functions, fluorescence-based binding assays to identify interaction partners, or electrophysiological methods if ion channel activity is suspected. Proteoliposome-based assays can be particularly valuable for functional studies, as they provide a membrane environment similar to the protein's native context. Mass spectrometry approaches, including hydrogen-deuterium exchange mass spectrometry (HDX-MS), can provide insights into protein dynamics and conformational changes upon ligand binding. For interaction studies, techniques such as surface plasmon resonance (SPR) or isothermal titration calorimetry (ITC) can quantify binding affinities with potential interaction partners identified through methods like co-immunoprecipitation or yeast two-hybrid screening.

How does Avin_36810 compare to other membrane proteins in Azotobacter vinelandii?

While specific comparative analyses of Avin_36810 with other membrane proteins in Azotobacter vinelandii are not directly addressed in the provided search results, we can draw some contextual insights from research on other membrane proteins in this organism. For instance, outer membrane protein I (OprI) in A. vinelandii has been found to play an unexpected role in poly-β-hydroxybutyrate (PHB) granule formation and accumulation . This finding challenges previous assumptions that membrane proteins detected on PHB granules were merely contaminants from extraction procedures, suggesting instead that some membrane proteins may have dual roles in both membrane structure and intracellular polymer metabolism . By analogy, Avin_36810 may similarly have functions beyond typical membrane protein roles. Sequence analysis tools could be employed to identify conserved domains shared with other membrane proteins of known function in A. vinelandii or related bacteria. Comparative expression studies examining how Avin_36810 expression correlates with other membrane proteins under various growth conditions might reveal functional relationships or co-regulated pathways. Structural predictions based on sequence analysis could also highlight similarities to other membrane proteins with established functions, providing hypotheses for further functional testing.

What potential biotechnological applications might Avin_36810 have?

Though specific biotechnological applications for Avin_36810 are not directly addressed in the search results, its nature as a membrane protein from Azotobacter vinelandii suggests several potential research avenues. Azotobacter vinelandii is already recognized for its biotechnological importance in producing biodegradable plastics through poly-β-hydroxybutyrate (PHB) synthesis , and membrane proteins often play crucial roles in cellular processes that can be harnessed for biotechnology. Potential applications could include using Avin_36810 as a model for studying membrane protein expression and purification methodologies, which remain challenging in protein production pipelines. If future research establishes transport functions for this protein, it might be engineered for enhanced nutrient uptake in bioremediation applications or optimized substrate transport in biocatalysis. Alternatively, if structural studies reveal unique properties, Avin_36810 might serve as a scaffold for designing novel membrane-associated enzymes or sensors. In vaccine development, bacterial membrane proteins can sometimes serve as antigens, though this would require extensive immunogenicity and safety testing. The development of antibodies against Avin_36810 could provide research tools for studying Azotobacter vinelandii physiology or detecting these bacteria in environmental samples.

What approaches can be used to study membrane localization and topology of Avin_36810?

Investigating the membrane localization and topology of Avin_36810 requires specialized approaches designed for membrane proteins. Fluorescence microscopy using protein fusions with fluorescent reporters (such as GFP) can visualize cellular localization, though care must be taken to ensure that tags do not disrupt membrane insertion or protein function. For determining membrane topology (the orientation of the protein within the membrane), protease protection assays can be employed, where intact cells, spheroplasts, or membrane vesicles are treated with proteases that can only access exposed protein regions. Subsequent mass spectrometry analysis of protected fragments can reveal which domains are exposed on each side of the membrane. Cysteine scanning mutagenesis, where individual cysteine residues are introduced throughout the protein and then labeled with membrane-impermeable sulfhydryl reagents, provides another approach to mapping topology. Computational prediction tools like TMHMM, Phobius, or TOPCONS can provide initial models of transmembrane regions and orientation based on the amino acid sequence, guiding experimental design. Cryo-electron microscopy of membrane preparations or reconstituted proteoliposomes represents a more advanced approach that could potentially provide structural information while preserving the membrane context, though this requires specialized equipment and expertise.

How can researchers effectively study protein-protein interactions involving Avin_36810?

Studying protein-protein interactions involving membrane proteins like Avin_36810 presents unique challenges due to their hydrophobic nature and requirements for membrane environments. Proximity-based labeling approaches such as BioID or APEX provide powerful tools for identifying interaction partners in their native cellular context, where a promiscuous biotin ligase or peroxidase fused to Avin_36810 biotinylates nearby proteins that can then be purified and identified by mass spectrometry. Co-immunoprecipitation studies using antibodies against Avin_36810 or its tagged versions require careful optimization of detergent conditions to maintain interactions while solubilizing the membrane protein complex. For targeted interaction studies, techniques such as surface plasmon resonance (SPR), microscale thermophoresis (MST), or biolayer interferometry can quantify binding parameters between Avin_36810 and candidate interaction partners. Bacterial two-hybrid systems adapted for membrane proteins offer genetic approaches to screening interaction partners, while split-fluorescent protein complementation assays can visualize interactions in living cells. Crosslinking mass spectrometry represents an advanced approach where chemical crosslinkers stabilize transient interactions before mass spectrometry analysis identifies the interaction sites at amino acid resolution. Each of these methods has specific strengths and limitations, and combining multiple approaches provides the most robust evidence for genuine interactions.

What strategies can resolve contradictory findings about Avin_36810 in the literature?

Resolving contradictions in scientific literature about proteins like Avin_36810 requires systematic approaches to identify sources of variability and determine the most reliable findings. As suggested by research on contradiction analysis in biomedical literature, automated text analysis techniques can help extract claims from the literature, flag potentially contradictory statements, and identify study characteristics that might explain discrepancies . For experimental resolution of contradictions, researchers should carefully examine methodological differences between studies, including expression systems, purification methods, buffer conditions, and analytical techniques, as these can significantly affect membrane protein behavior. Replication studies should be conducted using standardized protocols with clearly defined positive and negative controls to establish reproducibility. Meta-analysis approaches combining data from multiple studies can identify patterns and sources of variability across research groups. For contradictions related to protein function, researchers should consider whether differences reflect distinct activities under different conditions rather than true contradictions, as membrane proteins often have condition-dependent functions. Collaboration between groups reporting contradictory results can be particularly valuable, allowing direct comparison of materials and methods to pinpoint sources of variation. Publication of null or negative results should be encouraged to avoid literature bias toward positive findings.

What are common challenges in expressing and purifying Avin_36810, and how can they be addressed?

Membrane proteins like Avin_36810 present several challenges during expression and purification that require specialized approaches. Common issues include toxicity to expression hosts, formation of inclusion bodies, low expression levels, and difficulties in extraction and purification while maintaining native structure and function. To address these challenges, expression optimization strategies include using weaker inducible promoters to reduce toxicity, exploring different host strains optimized for membrane protein expression, or employing specialized expression vectors containing fusion partners that enhance membrane targeting and folding. The choice of detergent for extraction is critical, with mild detergents like DDM, LMNG, or digitonin often preferred for maintaining protein stability. A detergent screening approach is recommended to identify optimal conditions for Avin_36810 specifically. For purification, multi-step approaches combining affinity chromatography (utilizing the His-tag) with additional steps like ion exchange or size exclusion chromatography can improve purity without sacrificing yield . When membrane proteins form inclusion bodies, refolding protocols using controlled dilution into detergent micelles or artificial membranes can sometimes recover functional protein. For structural studies requiring larger quantities, scale-up strategies might include bioreactor cultivation with controlled dissolved oxygen levels and nutrient feeding strategies optimized for membrane protein production.

What controls and standards should be included in experiments involving Avin_36810?

Rigorous experimental design for Avin_36810 research requires appropriate controls and standards at each stage. For expression studies, controls should include non-induced cultures and expression of a well-characterized control membrane protein using the same system to benchmark expression efficiency. During purification, analysis of different cellular fractions (cytoplasmic, membrane, and insoluble) helps track protein localization, while purification of the tag alone (without Avin_36810) can help distinguish tag-specific from protein-specific behaviors during chromatography. For functional assays, negative controls should include denatured Avin_36810 preparations and buffers containing equivalent detergent concentrations but no protein. Positive controls pose a challenge without established functional assays, but might include related membrane proteins with known activities if available. For interaction studies, non-specific binding should be assessed using irrelevant proteins of similar size and charge properties. When using antibodies against Avin_36810, validation controls should include pre-immune serum samples and competition assays with purified protein to demonstrate specificity. Quantitative experiments should include standard curves with known concentrations of purified Avin_36810 when possible. For complex experiments, pilot studies with technical replicates help establish reproducibility and appropriate sample sizes for adequate statistical power, while biological replicates using independent protein preparations address preparation-to-preparation variability.

How can CRISPR-Cas9 and other gene editing techniques advance understanding of Avin_36810 function?

CRISPR-Cas9 and other gene editing technologies offer powerful approaches to investigate the function of Avin_36810 within its native cellular context. Knockout studies, where the Avin_36810 gene is deleted or disrupted, can reveal phenotypic consequences suggesting functional roles, though adaptation of CRISPR systems for Azotobacter vinelandii may require optimization of delivery methods and guide RNA design specific to this organism. Tagged endogenous expression, where CRISPR is used to introduce epitope or fluorescent tags at the genomic locus, allows visualization and purification of the protein at physiological expression levels without overexpression artifacts. Domain mapping through the introduction of precise mutations or truncations can identify functional regions within the protein, while conditional knockdown systems using CRISPRi (CRISPR interference) allow temporal control of expression to study acute versus chronic loss of function. Multiplexed CRISPR screens targeting potential interaction partners or functionally related genes can reveal genetic interactions suggesting pathway connections. High-throughput approaches combining CRISPR editing with phenotypic screening might identify conditions where Avin_36810 becomes essential or contributes to specific adaptive responses. Complementation studies, where wild-type or mutant versions are reintroduced into knockout strains, can confirm phenotype specificity and test structure-function hypotheses. These approaches collectively provide a comprehensive toolkit for functional genomics analysis of Avin_36810, offering insights that biochemical approaches alone might miss.

What computational approaches can predict functional properties of Avin_36810?

Computational approaches offer valuable tools for generating testable hypotheses about Avin_36810 function in the absence of comprehensive experimental data. Homology modeling, using related proteins with known structures as templates, can predict three-dimensional structure and identify potential functional sites, though template selection may be challenging for uncharacterized membrane proteins. Deep learning approaches like AlphaFold2 have revolutionized protein structure prediction and could provide structural models even without close homologs with known structures. Molecular dynamics simulations can investigate protein behavior within membrane environments, examining conformational flexibility and potential binding sites. Docking simulations with compound libraries might identify potential ligands or substrates for further experimental testing. Genomic context analysis, examining the conservation of genetic neighborhoods across bacterial species, can reveal functionally related genes often involved in the same biological processes. Co-expression network analysis using transcriptomic data can identify genes with similar expression patterns, suggesting functional relationships. Protein-protein interaction prediction tools can generate hypotheses about potential binding partners based on sequence features, while text mining approaches can extract information about related proteins from the scientific literature to guide experimental design. Integrative approaches combining multiple computational methods typically provide the most robust predictions, establishing priorities for experimental validation.

How might synthetic biology approaches utilize or modify Avin_36810 for novel applications?

Synthetic biology approaches offer exciting possibilities for utilizing or modifying Avin_36810 in biotechnological applications, though these would build upon further characterization of its native function. Protein engineering through directed evolution or rational design could enhance stability in heterologous expression systems or optimize activity for specific applications if functional properties are identified. Domain swapping with better-characterized membrane proteins could create chimeric proteins with novel functions while retaining membrane integration properties. As a potential scaffold, Avin_36810 might be modified to display functional peptides or binding domains on cellular surfaces, creating whole-cell biosensors or biocatalysts with membrane-anchored activities. For drug delivery applications, if structural studies reveal suitable properties, modified versions could potentially be incorporated into liposomes or nanoparticles to enhance targeting or controlled release. Metabolic engineering approaches might utilize Avin_36810 or derivatives to enhance membrane transport capabilities in production strains if transport functions are established. Synthetic minimal cell projects could incorporate Avin_36810 as a model membrane protein for studying fundamental aspects of membrane biology in simplified systems. Circuit design incorporating Avin_36810 as a sensor component might enable bacterial cells to detect and respond to specific environmental signals. While these applications require further fundamental characterization of the protein, they represent the translational potential that could emerge from basic research on this uncharacterized membrane protein.