Recombinant Schizosaccharomyces pombe GDT1-like protein C186.05c (SPAC186.05c)

What is SPAC186.05c and what are its known characteristics?

SPAC186.05c is a GDT1-like protein found in Schizosaccharomyces pombe (fission yeast), with UniProt accession number Q9P7Q0 . While the specific cellular function of this protein has not been fully characterized in the available literature, its classification as a GDT1-like protein suggests potential roles in ion homeostasis or membrane transport based on homologous proteins in other organisms.

The protein is commercially available as both full-length and partial recombinant versions with greater than 85% purity as determined by SDS-PAGE . When studying this protein, researchers should note that recombinant versions can be expressed in various expression systems including cell-free expression systems, E. coli, yeast, baculovirus, and mammalian cell systems, which may influence protein folding and post-translational modifications .

What storage conditions are optimal for maintaining SPAC186.05c stability?

The shelf life of recombinant SPAC186.05c is dependent on multiple factors including storage state, buffer composition, temperature, and the intrinsic stability of the protein itself. For optimal preservation, the following guidelines are recommended:

• Short-term storage: Working aliquots can be stored at 4°C for up to one week .

• Long-term storage:

  • Liquid form: 6 months at -20°C or -80°C .

  • Lyophilized form: 12 months at -20°C or -80°C .

For reconstitution, it is recommended to centrifuge the vial briefly before opening to bring contents to the bottom. The protein should be reconstituted in deionized sterile water to a concentration of 0.1-1.0 mg/mL. Addition of glycerol to a final concentration of 5-50% (with 50% being the standard) is recommended before aliquoting for long-term storage . Repeated freeze-thaw cycles should be avoided to maintain protein integrity and activity .

How should researchers design experiments to study SPAC186.05c function?

When designing experiments to study SPAC186.05c function, researchers should follow systematic experimental design principles. Begin by clearly defining your variables:

• Independent variables: These might include genetic manipulations of SPAC186.05c (knockout, overexpression, point mutations), environmental conditions, or chemical treatments .

• Dependent variables: Consider what outcomes you will measure, such as cell growth rate, protein localization, interaction with other proteins, or specific cellular processes .

• Control for extraneous variables: Factors such as temperature, media composition, cell density, and growth phase should be carefully controlled to ensure reproducible results .

A well-constructed experimental design would include appropriate controls:

• Negative controls: Wild-type strains or vehicle-only treatments

• Positive controls: Strains with known phenotypes related to your hypothesis

• Technical replicates: Multiple measurements of the same sample

• Biological replicates: Independent biological samples for each experimental condition

The specific methodological approach will depend on your research question, but could involve techniques such as gene deletion/complementation, fluorescent tagging for localization studies, co-immunoprecipitation for protein interaction studies, or phenotypic assays to assess function .

What are the recommended purification methods for recombinant SPAC186.05c?

Based on established purification protocols for recombinant proteins from S. pombe, the following methodology is recommended:

• Expression system selection: While multiple expression systems are available, mammalian cell expression systems may be particularly suitable for ensuring proper folding and post-translational modifications of SPAC186.05c .

• Cell lysis protocol:

  • Resuspend cell pellet in appropriate buffer (e.g., PBS pH 7.4, 137 mM NaCl, 2.7 mM KCl, 1 mM DTT)

  • Add 200 μg/ml lysozyme, protease inhibitor cocktail (e.g., cOmplete EDTA-free), and 0.1% NP-40

  • Agitate continuously on ice for 20 minutes

  • Sonicate three times for 30 seconds each, with 30-second pauses between sonications

  • Clear lysates by centrifugation at 10,000-13,000 rpm for 15-30 minutes

• Affinity purification: Depending on the tag used, employ appropriate affinity resin:

  • For GST-tagged proteins: Use GST-bind resin with batch purification for 2 hours at 4°C

  • For MBP-tagged proteins: Use amylose resin with batch purification for 2 hours at 4°C

  • Wash resin three times (5 minutes each at 4°C)

  • Elute with appropriate buffer (GST elution buffer: 50 mM Tris-HCl pH 8, 10 mM glutathione; MBP elution buffer: buffer supplemented with 10 mM maltose)

• Quality control: Verify protein purity using SDS-PAGE (should be ≥85%) .

• Storage: Aliquot purified protein, snap freeze, and store at -80°C for maximum stability .

What techniques are most effective for studying SPAC186.05c localization and dynamics?

To effectively study the localization and dynamics of SPAC186.05c in S. pombe, the following techniques are recommended:

• Fluorescent protein tagging:

  • C-terminal or N-terminal tagging with GFP, mCherry, or other fluorescent proteins

  • Ensure tag position does not interfere with protein function by performing complementation assays

  • Use time-lapse microscopy to monitor protein dynamics in living cells

• Immunofluorescence microscopy:

  • Use anti-SPAC186.05c antibodies like the rabbit polyclonal antibody against S. pombe SPAC186.05c

  • For co-localization studies, use antibodies against known organelle markers

  • Fix cells with appropriate methods for S. pombe (typically formaldehyde or methanol)

• Subcellular fractionation:

  • Separate cell components through differential centrifugation

  • Analyze protein distribution across fractions using western blotting

  • Compare distribution with known organelle markers

• Photobleaching techniques:

  • FRAP (Fluorescence Recovery After Photobleaching) to measure protein mobility

  • FLIP (Fluorescence Loss In Photobleaching) to assess continuity of protein pools

• Split-fluorescent protein assays:

  • To detect protein-protein interactions in specific subcellular locations

  • Can provide spatial information about interaction partners

How can researchers detect protein-protein interactions involving SPAC186.05c?

Multiple complementary approaches can be employed to detect and characterize protein-protein interactions involving SPAC186.05c:

• Co-immunoprecipitation (Co-IP):

  • Use anti-SPAC186.05c antibodies or antibodies against epitope tags

  • Include appropriate controls (IgG control, lysate from cells not expressing the target)

  • Analyze co-precipitated proteins by mass spectrometry or western blotting

  • For reversible or weak interactions, consider crosslinking before lysis

• Pull-down assays with recombinant proteins:

  • Use purified recombinant SPAC186.05c as bait

  • Incubate with cell lysates or purified candidate interacting proteins

  • Analyze bound proteins by SDS-PAGE followed by western blotting or mass spectrometry

• Yeast two-hybrid screening:

  • Use SPAC186.05c as bait to screen for interacting partners

  • Verify interactions with targeted yeast two-hybrid assays

  • Confirm interactions with orthogonal methods

• Proximity-based labeling:

  • BioID or TurboID fusion to SPAC186.05c for in vivo biotinylation of proximal proteins

  • APEX2 fusion for proximity-based labeling with biotin-phenol

  • Analyze biotinylated proteins by streptavidin pull-down and mass spectrometry

• Fluorescence-based methods:

  • FRET (Förster Resonance Energy Transfer) to detect direct interactions

  • BiFC (Bimolecular Fluorescence Complementation) to visualize interactions in cells

  • Split-luciferase assays for sensitive detection of protein-protein interactions

When reporting interaction data, include both positive and negative controls, quantify interaction strengths where possible, and validate key interactions through multiple independent methods.

How do post-translational modifications affect SPAC186.05c function?

While specific information about post-translational modifications (PTMs) of SPAC186.05c is limited in the provided search results, studying PTMs is critical for understanding protein regulation and function. A comprehensive approach to investigating PTMs would include:

• Identification of PTMs:

  • Mass spectrometry (MS) analysis of purified SPAC186.05c

  • Phosphoproteomics to identify phosphorylation sites

  • Enrichment strategies for specific modifications (e.g., TiO₂ for phosphopeptides)

• Functional analysis of PTMs:

  • Site-directed mutagenesis of modified residues (e.g., phospho-mimetic and phospho-null mutations)

  • Comparison of wildtype and mutant protein function in complementation assays

  • Temporal analysis of modifications during cell cycle or stress responses

• Regulation of PTMs:

  • Identification of enzymes responsible for adding/removing modifications

  • Kinase inhibitor studies for phosphorylation sites

  • Analysis of PTM changes in response to different conditions

Drawing parallels from research on other S. pombe proteins, such as the F-BAR protein Cdc15 which is regulated by phosphorylation by multiple kinases , researchers should consider how SPAC186.05c might be similarly regulated. For example, the study of Cdc15 revealed that mutating phosphorylation sites (as in the GST-Cdc15C-19A construct where 20 phosphorylation sites were mutated to alanine) can be a powerful approach to understanding the functional consequences of phosphorylation .

What approaches can be used to study SPAC186.05c in relation to cell physiology?

To understand the role of SPAC186.05c in cellular physiology, researchers should consider:

• Gene manipulation strategies:

  • If SPAC186.05c is an essential gene (by analogy to other essential S. pombe genes like hal3 ), use conditional expression systems

  • Temperature-sensitive mutants or auxin-inducible degron systems for controlled protein depletion

  • CRISPR/Cas9-based approaches for precise genome editing

• Physiological assays:

  • Growth assays under various stress conditions

  • Cell cycle analysis using flow cytometry

  • Metabolic profiling to identify altered metabolic pathways

• Comparative studies:

  • Analyze the role of SPAC186.05c homologs in other organisms

  • Consider the moonlighting functions observed in other S. pombe proteins

  • For instance, S. pombe hal3 encodes a fusion protein with three distinct activities

• Systems biology approaches:

  • Transcriptomics to identify genes affected by SPAC186.05c manipulation

  • Proteomics to characterize changes in protein abundance and modifications

  • Network analysis to place SPAC186.05c in biological pathways

• Structure-function studies:

  • Domain deletion/mutation analysis

  • Chimeric proteins to assess domain function

  • Structural modeling based on homologous proteins

These approaches should be integrated to develop a comprehensive understanding of SPAC186.05c's role in S. pombe physiology, considering potential moonlighting functions as observed with other proteins like Hal3 in both S. cerevisiae and S. pombe .

What are common issues when working with recombinant SPAC186.05c and how can they be addressed?

Researchers commonly encounter several challenges when working with recombinant proteins like SPAC186.05c. Here are solutions to frequently encountered problems:

How can researchers validate that recombinant SPAC186.05c retains its native function?

Validating that recombinant SPAC186.05c maintains its native function is crucial for ensuring experimental results are physiologically relevant. A comprehensive validation strategy includes:

• Functional complementation:

  • Express recombinant SPAC186.05c in a SPAC186.05c knockout or conditional mutant

  • Assess rescue of mutant phenotypes

  • Compare activity of different recombinant forms (full-length vs. partial)

• Biochemical activity assays:

  • Develop in vitro assays based on predicted function

  • Compare activity of recombinant protein to native protein extracted from S. pombe

  • Assess effects of different tags on protein activity

• Structural validation:

  • Circular dichroism to assess secondary structure

  • Limited proteolysis to evaluate folding

  • Thermal shift assays to measure protein stability

• Interaction verification:

  • Confirm that recombinant protein maintains known protein-protein interactions

  • Use pull-down assays with established binding partners

  • Compare binding affinities of recombinant vs. native protein

• Localization studies:

  • Express tagged recombinant protein in S. pombe

  • Verify correct subcellular localization

  • Assess dynamics using live-cell imaging

By drawing parallels from studies of other S. pombe proteins such as Hal3, which was shown to retain multiple distinct functions when expressed recombinantly , researchers can design appropriate validation strategies for SPAC186.05c.