Recombinant Schizosaccharomyces pombe Meiotically up-regulated gene 155 protein (mug155)

What is the molecular identity of mug155 protein and what cellular functions has it been implicated in?

The meiotically up-regulated gene 155 protein (mug155) is a 187-amino acid protein encoded by the SPAC27E2.04c gene locus in Schizosaccharomyces pombe . To properly investigate its cellular functions, researchers should implement a systematic approach combining genetic knockout studies, fluorescent tagging for localization analysis, and transcriptomic profiling during meiotic progression.

While definitive functions remain under investigation, methodological approaches should include:

• Creation of mug155Δ strains to assess phenotypic consequences during meiosis

• Temporal expression analysis through synchronized meiotic cultures

• Subcellular fractionation coupled with western blotting

• Co-immunoprecipitation to identify physical interaction partners

Current research suggests involvement in meiotic processes based on its classification as a meiotically up-regulated gene, though specific molecular mechanisms require further characterization.

What experimental evidence supports the classification of mug155 as "meiotically up-regulated"?

To validate and extend our understanding of mug155's meiotic upregulation, researchers should implement the following methodological approaches:

• Quantitative RT-PCR across synchronized meiotic time points using the following experimental design:

  • Culture synchronization using nitrogen starvation protocols

  • Sample collection at 0, 1, 2, 4, 6, 8, and 10 hours after meiotic induction

  • RNA extraction with hot phenol method optimized for yeast

  • cDNA synthesis with oligo-dT and random hexamer primers

  • qPCR with mug155-specific primers normalized to constitutive genes (act1, cdc2)

• RNA-seq analysis comparing vegetative growth vs. meiotic timepoints

• Promoter analysis using:

  • In silico identification of meiosis-specific transcription factor binding sites

  • Reporter gene constructs with wild-type and mutated promoter variants

  • ChIP-seq for meiotic transcription factors at the mug155 locus

The experimental design should include appropriate controls and replication as specified in experimental design principles , with a minimum of three biological replicates and two technical replicates per condition.

Which protein domains and functional motifs characterize mug155, and how can researchers identify them?

For comprehensive identification of functional domains and motifs in mug155, researchers should employ a systematic analytical workflow:

• Primary Sequence Analysis:

  • PROSITE scanning for consensus motifs

  • PRINTS and BLOCKS searches for conserved sequence patterns

  • Signal peptide prediction using SignalP

  • Post-translational modification prediction (NetPhos, NetOGlyc, NetNGlyc)

• Structural Analysis:

  • Secondary structure prediction (JPred, PSIPRED)

  • Disorder prediction (DISOPRED, IUPred)

  • Coiled-coil prediction (COILS, Paircoil)

  • Transmembrane region analysis (TMHMM, Phobius)

• Functional Motif Identification:

  • Linear motif scanning (ELM database)

  • DNA/RNA binding prediction (BindN, RNABindR)

  • Nuclear localization/export signal identification (NLStradamus, NetNES)

The sequence "KIRCRLKKKFI" (positions 65-75) suggests a potential nuclear localization signal that warrants experimental validation through mutagenesis and localization studies.

How does mug155 expression vary temporally during different phases of meiosis in S. pombe?

To comprehensively profile mug155 expression throughout meiosis, researchers should implement a multi-faceted approach:

• High-resolution temporal expression analysis:

  • Synchronized cultures using temperature-sensitive pat1-114 mutant

  • Sample collection at 15-minute intervals for the first 4 hours, then 30-minute intervals

  • Parallel assessment of known meiotic phase markers (rec8, mei4, spo6)

• Protein-level quantification:

  • Western blotting with anti-mug155 antibodies or epitope-tagged mug155

  • Pulse-chase experiments to determine protein half-life

  • Fluorescent reporter fusions for live-cell imaging

• Single-cell analysis:

  • smFISH (single-molecule fluorescence in situ hybridization) for mRNA detection

  • Flow cytometry of GFP-tagged mug155 to assess population heterogeneity

The experimental design should incorporate randomized block design with appropriate controls as outlined in experimental design principles , ensuring statistical validity of temporal expression patterns.

What methodologies are most effective for identifying interaction partners of mug155?

For comprehensive characterization of mug155 protein-protein interactions, researchers should implement a multi-technique approach:

• Affinity Purification-Mass Spectrometry (AP-MS):

  • Tandem affinity purification with His-tagged recombinant mug155

  • On-bead digestion followed by LC-MS/MS

  • Quantitative comparison between meiotic and vegetative conditions

  • SAINT algorithm for filtering non-specific interactions

• Yeast Two-Hybrid Screening:

  • Construction of mug155 bait fused to DNA-binding domain

  • Screening against S. pombe meiotic cDNA library

  • Validation of interactions through reverse Y2H

  • Analysis of interaction domains through truncation constructs

• Proximity-Based Labeling:

  • BioID or TurboID fusion to mug155

  • In vivo biotin labeling during meiotic progression

  • Streptavidin pull-down and MS identification

  • Temporal mapping of interaction networks

• Co-immunoprecipitation Validation:

  • Endogenous tagging of candidate interactors

  • Reciprocal co-IP experiments

  • Sequential IP to identify complex composition

  • Crosslinking IP for transient interactions

The experimental design should follow a completely randomized design with multiple biological replicates. Statistical analysis should employ appropriate filtering criteria to distinguish true interactors from background contaminants, with significance thresholds adjusted for multiple comparisons.

How can the functional contribution of mug155 to meiotic processes be systematically characterized?

To elucidate mug155's functional contributions to meiosis, researchers should implement a comprehensive experimental strategy:

• Genetic Approaches:

  • Generation of mug155 null, conditional, and separation-of-function mutants

  • Complementation with wild-type and mutant alleles

  • Synthetic genetic interaction screening with known meiotic factors

  • Construction of analog-sensitive alleles for acute inhibition

• Cytological Analysis:

  • Immunofluorescence microscopy of meiotic chromosome structures

  • Live-cell imaging of fluorescently tagged mug155 with meiotic markers

  • Electron microscopy of synaptonemal complex formation

  • Super-resolution microscopy for precise localization

• Biochemical Characterization:

  • In vitro reconstitution of mug155-containing complexes

  • Activity assays based on predicted biochemical functions

  • Chromatin association analysis through ChIP-seq

  • Post-translational modification profiling during meiotic progression

• Phenotypic Assessment:

  • Quantification of meiotic progression timing

  • Measurement of recombination frequency and distribution

  • Analysis of chromosome segregation fidelity

  • Sporulation efficiency and spore viability determination

The experimental design should incorporate factorial approaches to test for potential genetic interactions, with replication and randomization principles applied as recommended in experimental design literature .

What bioinformatic strategies should be employed to identify and characterize mug155 homologs across species?

For comprehensive evolutionary analysis of mug155, researchers should implement a systematic bioinformatic pipeline:

• Sequence-Based Homology Detection:

  • Position-Specific Iterative BLAST (PSI-BLAST) with graduated E-value thresholds

  • Profile Hidden Markov Model searches using HMMER

  • Sensitive fold-recognition methods (HHpred, PHYRE2)

  • Domain architecture analysis to identify partial homologs

• Phylogenetic Analysis:

  • Multiple sequence alignment with MAFFT or T-Coffee

  • Alignment curation with Gblocks or TrimAl

  • Model selection using ProtTest

  • Maximum likelihood tree construction (RAxML, IQ-TREE)

  • Bayesian inference (MrBayes, PhyloBayes)

• Synteny and Genomic Context Analysis:

  • Microsynteny mapping across fungal genomes

  • Analysis of conserved gene neighborhoods

  • Identification of orthologous genomic regions

• Functional Divergence Assessment:

  • Site-specific evolutionary rate analysis

  • Prediction of functionally important residues

  • Molecular evolutionary analyses for positive selection

  • Ancestral sequence reconstruction

This methodological framework should be applied hierarchically, first within Schizosaccharomyces species, then expanding to other yeasts, fungi, and eventually eukaryotes, with appropriate statistical validation at each step.

What are the optimal conditions for expressing recombinant mug155 in E. coli?

For maximizing expression and solubility of recombinant mug155, researchers should systematically optimize the following parameters:

• Expression System Selection:

  • Recommended primary system: E. coli BL21(DE3) with pET-based vector and His-tag

  • Alternative systems for optimization: Rosetta(DE3) for rare codon usage, Origami for disulfide bond formation

• Induction Parameters Optimization:

  Parameter	Variables to Test	Initial Recommendation
  Temperature	16°C, 25°C, 30°C, 37°C	25°C
  IPTG concentration	0.1, 0.5, 1.0 mM	0.5 mM
  Induction duration	3h, 6h, overnight	6h
  Media composition	LB, TB, 2xYT, M9	TB
  OD600 at induction	0.4, 0.6, 0.8, 1.0	0.6

• Solubility Enhancement Strategies:

  • Co-expression with chaperones (GroEL/GroES, DnaK/DnaJ)

  • Addition of solubility tags (MBP, SUMO, Trx)

  • Culture additives (5-10% glycerol, 0.1-1% glucose)

  • Low-temperature autoinduction

• Harvest and Initial Processing:

  • Cell lysis optimization (sonication vs. French press vs. chemical lysis)

  • Solubility assessment in various buffers

  • Initial clarification through high-speed centrifugation (20,000 × g)

The experimental approach should follow a factorial design to identify interaction effects between variables , with a minimum of three biological replicates per condition. Expression levels should be quantified by SDS-PAGE densitometry and Western blotting, with protein solubility assessed by comparing supernatant vs. pellet fractions.

What purification strategy will yield the highest purity and biological activity for recombinant mug155?

For optimal purification of His-tagged recombinant mug155, researchers should implement a multi-step chromatography protocol:

• Primary Affinity Chromatography:

  • IMAC (Immobilized Metal Affinity Chromatography) using Ni-NTA resin

  • Buffer optimization: Tris/PBS-based buffer, pH 8.0 with 6% trehalose

  • Imidazole gradient elution (20-250 mM)

  • On-column refolding option for inclusion bodies

• Secondary Purification:

  • Size Exclusion Chromatography (Superdex 75/200)

  • Ion Exchange Chromatography (Resource Q/S)

  • Hydrophobic Interaction Chromatography as needed

• Quality Control Assessment:

  • SDS-PAGE with silver staining (target >90% purity)

  • Western blotting with anti-His antibodies

  • Mass spectrometry validation

  • Dynamic light scattering for aggregation analysis

  • Thermal shift assay for stability assessment

• Storage Optimization:

  • Final buffer: Tris/PBS with 6% trehalose, pH 8.0

  • Aliquoting to avoid freeze-thaw cycles

  • Flash freezing in liquid nitrogen

  • Storage at -80°C for long-term stability

  • Addition of 5-50% glycerol for cryoprotection

For reconstitution, researchers should dissolve lyophilized protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL , followed by addition of glycerol to 50% final concentration for storage stability.

The purification strategy should be validated through activity assays appropriate to the protein's function, with yields and purity documented at each chromatographic step.

What experimental design principles should guide in vivo studies of mug155 function?

For rigorous investigation of mug155 function in vivo, researchers should adhere to these experimental design principles:

• Genetic Manipulation Approaches:

  • Complete gene deletion (mug155Δ)

  • Conditional expression systems (nmt1 promoter series)

  • Auxin-inducible degron for rapid protein depletion

  • Site-directed mutagenesis of critical residues

  • Fluorescent protein tagging at N/C termini

• Experimental Design Structure:

  • Implement completely randomized design for single-factor experiments

  • Use randomized block design for multi-factor experiments to control for batch effects

  • Ensure adequate biological replicates (minimum n=3)

  • Include appropriate genetic controls (wild-type, unrelated deletion strains)

• Phenotypic Characterization Matrix:

  Aspect	Methodologies	Quantitative Metrics
  Meiotic progression	Time-lapse microscopy	Timing of phase transitions
  Chromosome dynamics	Live-cell imaging	Bouquet formation, oscillation amplitude
  Recombination	Genetic assays, Immunofluorescence	Crossover frequency, Rad51 foci count
  Spore formation	Tetrad dissection	Spore viability, segregation patterns

• Statistical Analysis Framework:

  • Power analysis to determine sample size requirements

  • ANOVA for multi-group comparisons

  • Post-hoc tests with appropriate multiple testing correction

  • Effect size calculation for biological significance assessment

Which biochemical assays are most appropriate for characterizing mug155 protein-protein and protein-nucleic acid interactions?

To comprehensively characterize the molecular interactions of mug155, researchers should employ a complementary suite of biochemical assays:

• Protein-Protein Interaction Assays:

  • Surface Plasmon Resonance (SPR):

    • Immobilize purified His-tagged mug155 on sensor chip

    • Flow candidate interactors at varying concentrations

    • Determine kon, koff, and KD values

    • Perform competition assays to identify binding sites

  • Microscale Thermophoresis (MST):

    • Label mug155 with fluorescent dye

    • Titrate unlabeled interaction partners

    • Analyze thermophoretic mobility shifts

    • Suitable for weak and transient interactions

  • Isothermal Titration Calorimetry (ITC):

    • Direct measurement of binding thermodynamics

    • Determination of stoichiometry, binding affinity, enthalpy

    • No labeling or immobilization required

• Protein-Nucleic Acid Interaction Assays:

  • Electrophoretic Mobility Shift Assay (EMSA):

    • Incubate recombinant mug155 with labeled DNA/RNA

    • Analyze mobility shifts on native PAGE

    • Perform competition assays with unlabeled nucleic acids

  • Fluorescence Anisotropy:

    • Use fluorescently labeled oligonucleotides

    • Titrate with increasing mug155 concentrations

    • Determine binding constants and specificity

  • Chromatin Immunoprecipitation (ChIP):

    • In vivo crosslinking of protein-DNA interactions

    • Immunoprecipitation with anti-mug155 antibodies

    • NGS or qPCR analysis of bound DNA sequences

• Structural Characterization:

  • Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS) to map interaction interfaces

  • Cross-linking Mass Spectrometry (XL-MS) to identify proximity relationships

  • Small-Angle X-ray Scattering (SAXS) for complex architecture

The experimental design should follow factorial approaches with appropriate randomization and replication , and include negative controls (BSA, unrelated proteins) and positive controls (known interaction partners if available).

What statistical framework should be applied when analyzing expression data for mug155?

For robust analysis of mug155 expression data, researchers should implement a comprehensive statistical framework:

• Preprocessing and Quality Control:

  • RNA-seq data: Quality filtering, adapter trimming, alignment to S. pombe genome

  • qRT-PCR data: Assessment of primer efficiency, melt curve analysis

  • Outlier detection through robust statistical methods (Grubb's test, Cook's distance)

• Normalization Strategies:

  • RNA-seq: RPKM/FPKM, TPM, or DESeq2 normalization

  • qRT-PCR: ΔΔCt method with validated reference genes (act1, cdc2)

  • Batch effect correction using ComBat or surrogate variable analysis

• Statistical Testing Framework:

  • Time-course analysis using maSigPro or ImpulseDE2

  • Differential expression analysis using DESeq2 or edgeR

  • ANOVA for multi-group comparisons with appropriate post-hoc tests

  • Non-parametric alternatives (Kruskal-Wallis) for non-normally distributed data

• Experimental Design Considerations:

  • Implement completely randomized design for simple comparisons

  • Use randomized block design to control for batch effects

  • Ensure minimum of three biological replicates per condition

  • Perform power analysis to determine sample size requirements

• Visualization Approaches:

  • MA plots for differential expression

  • Clustered heatmaps for expression patterns

  • Principal Component Analysis for global variation

  • Gene Set Enrichment Analysis for functional interpretation

Statistical significance should be assessed at α=0.05 with appropriate multiple testing correction (Benjamini-Hochberg procedure), and biological significance should be evaluated through effect size measurements (log2 fold change ≥1).

How should researchers design and analyze experiments to resolve contradictory findings about mug155 function?

When faced with contradictory findings about mug155 function, researchers should implement a systematic resolution strategy:

• Methodological Reconciliation Approach:

  • Critical Comparison of Experimental Conditions:

    • Strain background differences (h+, h-, h90)

    • Culture conditions (media composition, temperature)

    • Induction methods (nitrogen starvation vs. temperature shift)

    • Timing of observations (synchronization quality)

  • Technical Validation Across Platforms:

    • Validate expression changes with orthogonal methods (RNA-seq + qRT-PCR + Western blot)

    • Confirm phenotypes with multiple assays (microscopy + biochemical tests)

    • Cross-validate protein interactions with different techniques (Y2H, co-IP, BioID)

• Integrated Experimental Design:

  • Factorial design incorporating variables from contradictory studies

  • Split-plot design for complex multi-variable experiments

  • Inclusion of positive and negative controls from both contradictory studies

  • Blinded analysis to minimize confirmation bias

• Statistical Framework for Resolution:

  • Meta-analysis of multiple datasets

  • Bayesian analysis incorporating prior knowledge

  • Effect size calculation to assess biological significance

  • Equivalence testing to establish compatibility of findings

• Mechanistic Investigation of Contradictions:

  • Generate testable hypotheses to explain contradictions

  • Identify potential context-dependent functions

  • Design experiments specifically targeting variable conditions

  • Develop computational models to reconcile disparate observations

The resolution strategy should follow principles of replication, randomization, and local control to ensure statistical validity, with emphasis on identifying interaction effects between experimental variables that may explain contradictory findings.

What bioinformatic tools and pipelines are most effective for structural and functional prediction of mug155?

For comprehensive computational characterization of mug155, researchers should implement an integrated bioinformatic workflow:

This integrated pipeline leverages complementary approaches to enhance prediction accuracy. Results should be critically evaluated through confidence metrics and consensus approaches, with experimental validation of key predictions.

What guidelines should researchers follow when planning experiments with recombinant mug155 protein?

When designing experiments with recombinant mug155 protein, researchers should adhere to these comprehensive guidelines:

• Pre-Experimental Planning:

  • Protein Specification:

    • Use full-length (1-187 amino acids) His-tagged recombinant protein

    • Consider domain-specific constructs for targeted studies

    • Evaluate tag position (N vs C-terminal) effects on function

  • Experimental Design Structure:

    • Implement completely randomized design for single-factor experiments

    • Use randomized block design for multi-factor experiments

    • Ensure minimally three biological replicates per condition

    • Include appropriate positive and negative controls

• Handling and Storage Protocols:

  • Reconstitution Procedure:

    • Centrifuge vial briefly before opening

    • Reconstitute in deionized sterile water to 0.1-1.0 mg/mL

    • Add glycerol to 5-50% final concentration for stability

  • Storage Guidelines:

    • Store at -20°C/-80°C as aliquots to avoid freeze-thaw cycles

    • Working aliquots can be maintained at 4°C for up to one week

    • Use Tris/PBS-based buffer with 6% trehalose at pH 8.0

• Experimental Quality Control:

  • Protein Validation:

    • Verify >90% purity by SDS-PAGE

    • Confirm identity by mass spectrometry

    • Assess structural integrity by circular dichroism

  • Activity Benchmarking:

    • Develop functional assays relevant to mug155's predicted activity

    • Establish dose-response relationships

    • Determine stability under experimental conditions

• Data Collection and Analysis:

  • Pre-register experimental protocols and analysis plans

  • Implement appropriate statistical tests based on experimental design

  • Report effect sizes alongside p-values

  • Document all experimental conditions thoroughly