Recombinant Schizosaccharomyces pombe Uncharacterized membrane protein C6F6.13c (SPAC607.08c)

What is the basic structural information of S. pombe Uncharacterized membrane protein C6F6.13c?

The uncharacterized membrane protein C6F6.13c (SPAC607.08c) is encoded by the gene SPAC607.08c in Schizosaccharomyces pombe (fission yeast). It is identified in the UniProt database with accession number Q9US10. The protein contains multiple transmembrane domains characteristic of membrane proteins. Its full amino acid sequence includes regions with high hydrophobicity consistent with membrane insertion, and portions that likely form extracellular or cytoplasmic domains .

The protein's amino acid sequence contains motifs suggesting potential involvement in transport or signaling functions, though its precise function remains uncharacterized. Structural analysis indicates the presence of:

• Multiple transmembrane helices

• Potential glycosylation sites

• Conserved domains that may be involved in protein-protein interactions

Unlike many characterized membrane proteins, C6F6.13c lacks clear functional domain annotations, making it an interesting subject for fundamental research into protein function discovery.

How does S. pombe Uncharacterized membrane protein C6F6.13c compare to similar proteins in other species?

Comparative analysis of C6F6.13c with other uncharacterized membrane proteins, such as C622.02 (SPCC622.02), reveals both similarities and differences in their structural organization. While both are membrane proteins with multiple predicted transmembrane domains, they differ in their amino acid sequences and potential functional motifs .

Homology searches against protein databases indicate that C6F6.13c shares limited sequence similarity with membrane proteins in other yeast species and more distantly related eukaryotes. The conservation pattern suggests:

• The core transmembrane regions show higher conservation than loop regions

• Potential functional motifs are partially conserved across related species

• The protein may belong to a family of membrane proteins with divergent functions

Understanding these evolutionary relationships can provide insights into the potential functions of C6F6.13c that could guide targeted experimental approaches.

What expression systems are most effective for producing Recombinant S. pombe Uncharacterized membrane protein C6F6.13c?

Recombinant production of membrane proteins presents significant challenges due to their hydrophobic nature and requirements for proper membrane insertion. For S. pombe Uncharacterized membrane protein C6F6.13c, several expression systems have been employed with varying levels of success.

The baculovirus expression system has shown efficacy for producing related S. pombe membrane proteins with retention of structural integrity. This system provides the eukaryotic processing machinery necessary for proper protein folding and post-translational modifications . Alternative expression systems include E. coli, yeast, and mammalian cell systems, each with specific advantages and limitations .

For optimal expression, consider the following methodological approaches:

• Baculovirus system: Offers proper protein folding and post-translational modifications

  • Optimal MOI (multiplicity of infection): 2-5

  • Expression time: 48-72 hours

  • Temperature: 27°C

• Yeast expression systems: Homologous environment may improve folding

  • Preferable vectors: pREP series with thiamine-repressible promoters

  • Induction conditions: Thiamine depletion for 16-24 hours

• E. coli systems: Higher yield but challenges with membrane insertion

  • Recommended strains: C41(DE3) or C43(DE3) designed for membrane proteins

  • Induction: 0.1-0.5 mM IPTG at lower temperatures (16-20°C)

Selection of the appropriate expression system should be guided by the specific experimental requirements and downstream applications.

What are the most critical factors for successful purification of the recombinant protein?

Purification of recombinant uncharacterized membrane protein C6F6.13c requires careful optimization to maintain protein stability and functionality. Based on purification protocols for similar membrane proteins, the following factors are critical:

Detergent selection: The choice of detergent is crucial for solubilizing the membrane protein while maintaining its native conformation. A systematic evaluation of different detergents is recommended, starting with milder options such as n-dodecyl β-D-maltoside (DDM) or n-octyl-β-D-glucopyranoside (OG) .

Buffer optimization: The stability of C6F6.13c is influenced by buffer composition:

• Tris-based buffers (pH 7.5-8.0) have proven effective

• Addition of glycerol (30-50%) enhances stability

• Inclusion of specific lipids may help maintain native conformation

Purification strategy: A multi-step approach typically yields the best results:

• Initial affinity chromatography using an appropriate tag (His, FLAG, etc.)

• Size exclusion chromatography to remove aggregates

• Optional ion exchange chromatography for higher purity

For long-term storage, the protein should be maintained in a stabilizing buffer containing 50% glycerol at -20°C/-80°C to prevent degradation .

How can fluorescent tagging be used to study localization and dynamics of C6F6.13c in S. pombe cells?

Fluorescent tagging is a powerful approach for investigating the subcellular localization and dynamics of uncharacterized membrane proteins like C6F6.13c. Endogenous tagging methods in S. pombe provide advantages over overexpression systems by maintaining native expression levels and regulation .

Methodology for endogenous tagging:

• Selection of fluorescent tag:

  • mNeonGreen (mNG) offers superior brightness and photostability

  • mCherry provides good spectral separation for co-localization studies

  • Tag position (N- or C-terminal) should be evaluated for functional interference

• Integration strategy:

  • PCR-based gene targeting with long homology regions (80-100 bp)

  • Targeting cassette containing the fluorescent tag and a selection marker

  • Verification of correct integration by PCR and sequencing

• Imaging and analysis:

  • Confocal microscopy for high-resolution localization

  • Time-lapse imaging to track protein dynamics

  • Quantitative analysis using neural network segmentation tools like YeaZ for whole-cell analysis

The choice of imaging methodology should be guided by the specific research question, with consideration for the protein's expected dynamics and the cellular context.

What approaches can be used to investigate the function of this uncharacterized membrane protein?

Investigating the function of uncharacterized membrane proteins like C6F6.13c requires a multi-faceted approach combining genetic, biochemical, and cell biological techniques. The following methodological framework can guide functional characterization:

Genetic approaches:

• Gene deletion/disruption to assess phenotypic consequences

• Creation of conditional mutants (temperature-sensitive or auxin-inducible degrons)

• Genetic interaction screens to identify functional relationships

Biochemical approaches:

• Identification of interaction partners through co-immunoprecipitation coupled with mass spectrometry

• Assessment of post-translational modifications that might regulate function

• In vitro assays for specific activities (e.g., ATPase, transporter, or signaling functions)

Cell biological approaches:

• Localization studies in response to various stimuli or cell cycle stages

• Correlation of protein levels/localization with cell cycle progression using fission yeast's length as a proxy for cell cycle position

• Perturbation experiments to assess response to stress conditions

By integrating data from these complementary approaches, researchers can develop and test hypotheses about the protein's function in cellular processes.

How can quantitative analysis of C6F6.13c concentration changes be correlated with cell cycle progression?

Fission yeast presents unique advantages for studying protein dynamics during the cell cycle due to its simple rod-shaped geometry and growth pattern. Cell length can serve as a reliable indicator of cell cycle position, allowing precise correlation between protein levels and cell cycle stage in asynchronous populations .

Methodological approach for quantitative analysis:

• Sample preparation and imaging:

  • Endogenously tag C6F6.13c with a fluorescent protein

  • Image asynchronous populations to capture cells at various cell cycle stages

  • Include nuclear markers (e.g., Cut11-mCherry) for accurate nuclear segmentation

• Image analysis and quantification:

  • Implement neural network-based cell segmentation (e.g., YeaZ)

  • Measure cell length as a proxy for cell cycle position

  • Quantify whole-cell protein concentration by calculating total fluorescence intensity normalized to cell volume

  • For nuclear concentration, segment nuclei using markers and measure nuclear fluorescence intensity

• Data analysis and interpretation:

  • Plot protein concentration against cell length/cell cycle position

  • Apply statistical methods to identify significant concentration changes

  • Compare nuclear vs. cytoplasmic concentration dynamics

This approach can reveal whether C6F6.13c exhibits cell cycle-dependent concentration changes similar to known cell cycle regulators, which typically show peaks at specific cell cycle transitions .

What considerations are important when designing experiments to investigate potential roles of C6F6.13c in cell size control or ploidy sensing?

Investigating the potential involvement of C6F6.13c in cell size control or ploidy sensing requires careful experimental design that accounts for the complex regulatory networks governing these processes in fission yeast.

Key experimental design considerations:

• Genetic background selection:

  • Use well-characterized strains with defined cell cycle properties

  • Consider genetic interactions with known cell size regulators (cdc2, cdc13, cdc25, wee1)

  • Create double mutants to test for synthetic interactions

• Measurement parameters and controls:

  • Precisely measure cell size at division using standardized imaging protocols

  • Assess nuclear concentration dynamics, as proteins involved in ploidy sensing often exhibit nuclear localization patterns

  • Include appropriate controls (known cell size regulators) for comparative analysis

• Experimental perturbations:

  • Manipulate C6F6.13c levels through controlled expression systems

  • Assess effects on cell cycle timing and size homeostasis

  • Test response to ploidy changes using haploid/diploid comparisons

• Data collection and analysis:

  • Collect single-cell measurements from large populations (>1000 cells)

  • Apply statistical methods to detect subtle phenotypic changes

  • Develop mathematical models to interpret results in the context of known regulatory networks

By systematically addressing these considerations, researchers can generate robust data on the potential involvement of C6F6.13c in fundamental processes of cell growth and division control.

What are the primary challenges in maintaining stability of purified recombinant C6F6.13c, and how can they be addressed?

Membrane proteins present unique challenges for maintaining stability after purification. For C6F6.13c, several specific issues and solutions have been identified:

Challenge 1: Protein aggregation

• Solution: Optimize detergent concentration and type during purification

• Method: Screen detergent series (DDM, LMNG, OG) at various concentrations

• Assessment: Monitor aggregation using dynamic light scattering or size exclusion chromatography

Challenge 2: Functional denaturation

• Solution: Include specific lipids that might be required for structural integrity

• Method: Supplement purification buffers with lipid mixtures (POPC, POPE, cholesterol)

• Assessment: Compare activity/stability with and without lipid supplementation

Challenge 3: Storage stability

• Solution: Optimize storage conditions to prevent degradation

• Method: Test various buffers with glycerol concentrations ranging from 5-50%

• Recommendation: Store at -20°C/-80°C with 50% glycerol for optimal long-term stability

Challenge 4: Freeze-thaw degradation

• Solution: Minimize freeze-thaw cycles

• Method: Aliquot purified protein into single-use volumes

• Recommendation: Store working aliquots at 4°C for up to one week to avoid repeated freezing

How can researchers address the contradiction between maintaining native structure and achieving sufficient yield for functional studies?

The inherent tension between protein yield and native structure preservation represents a significant challenge in membrane protein research. For C6F6.13c, this contradiction can be addressed through methodological optimization:

Systematic expression optimization:

• Test multiple expression systems in parallel (baculovirus, yeast, E. coli)

• Optimize expression conditions for each system (temperature, induction time, media composition)

• Evaluate both yield and quality metrics for each condition

Purification strategy refinement:

• Implement mild solubilization conditions even at the cost of reduced yield

• Consider native purification approaches that preserve the lipid environment

• Develop a two-track purification protocol: one optimized for structural studies (emphasizing quality) and another for functional assays (prioritizing yield)

Reconstitution approaches:

• Explore nanodiscs or liposome reconstitution to restore native-like membrane environment

• Optimize lipid composition based on S. pombe membrane lipid analysis

• Validate structural integrity through biophysical techniques (circular dichroism, fluorescence spectroscopy)

Compromise strategies:

• Determine the minimal protein concentration required for each experimental application

• Scale up expression volumes rather than pushing expression levels to maintain quality

• Consider fragment-based approaches for structural studies if full-length protein proves challenging

By systematically addressing these considerations, researchers can develop protocols that achieve an optimal balance between yield and native structure preservation.

How might integrating multi-omics approaches advance our understanding of C6F6.13c function?

Understanding the function of uncharacterized membrane proteins like C6F6.13c can be significantly enhanced through the integration of multiple omics technologies. This approach provides complementary perspectives on protein function and cellular context:

Transcriptomics integration:

• RNA-seq analysis comparing wild-type and C6F6.13c deletion strains

• Identification of differentially expressed genes to infer functional pathways

• Investigation of expression correlation networks to identify potential functional relationships

Proteomics approaches:

• Quantitative proteomics to identify changes in protein abundance in response to C6F6.13c manipulation

• Interaction proteomics (BioID, APEX) to map the protein's interaction network

• Post-translational modification analysis to identify regulatory mechanisms

Metabolomics integration:

• Targeted and untargeted metabolite profiling to identify metabolic changes

• Stable isotope labeling to trace metabolic fluxes

• Correlation of metabolic changes with phenotypic observations

Data integration strategy:

• Generate multi-omics datasets under identical experimental conditions

• Apply computational integration methods to identify consistent patterns

• Develop testable hypotheses based on integrative analysis

• Validate predictions experimentally

This multi-omics approach can provide a systems-level understanding of C6F6.13c function and place it within the broader cellular context of fission yeast biology.

What emerging technologies might facilitate structural characterization of membrane proteins like C6F6.13c?

Structural characterization of membrane proteins has historically been challenging, but several emerging technologies are reshaping this landscape and may be applicable to C6F6.13c:

Cryo-electron microscopy advancements:

• Single-particle cryo-EM has revolutionized membrane protein structural biology

• Technological improvements in detectors and processing algorithms continue to improve resolution

• Sample preparation innovations specifically designed for membrane proteins enhance success rates

Integrative structural biology approaches:

• Combining multiple structural techniques (X-ray crystallography, NMR, SAXS, cryo-EM)

• Computational integration of partial structural data from complementary methods

• Structural proteomics approaches like cross-linking mass spectrometry to define domain interactions

Computational structure prediction:

• AlphaFold2 and RoseTTAFold have demonstrated remarkable accuracy for membrane protein prediction

• Specialized prediction algorithms that incorporate lipid environment considerations

• Molecular dynamics simulations to refine predicted structures in membrane contexts

Emerging biophysical techniques:

• Microcrystal electron diffraction (MicroED) for small crystals of membrane proteins

• Native mass spectrometry for intact membrane protein complexes

• Single-molecule FRET to probe conformational dynamics

These emerging approaches offer complementary strengths that, when combined, could overcome the traditional challenges of membrane protein structural biology and provide crucial insights into the structure-function relationship of C6F6.13c.