Recombinant Populus trichocarpa CASP-like protein POPTRDRAFT_820327 (POPTRDRAFT_820327)

What is the basic identification information for POPTRDRAFT_820327?

POPTRDRAFT_820327 is a CASP-like protein from Populus trichocarpa (Western balsam poplar), also known as Populus balsamifera subsp. trichocarpa. The protein has a UniProt accession number of B9HMF8 and is characterized as a full-length protein consisting of 186 amino acids . The recommended name in scientific literature is "CASP-like protein POPTRDRAFT_820327" with POPTRDRAFT_820327 being the designated ORF name for the gene that encodes this protein .

How should researchers properly designate this protein in scientific publications?

When referencing this protein in scientific literature, researchers should use the full nomenclature "CASP-like protein POPTRDRAFT_820327" on first mention, along with the organism name "Populus trichocarpa" and UniProt accession number (B9HMF8) . For subsequent mentions, "POPTRDRAFT_820327" is sufficient. Avoid creating nonstandard abbreviations. When describing recombinant versions, specify the expression system (e.g., "Recombinant Populus trichocarpa CASP-like protein POPTRDRAFT_820327 expressed in E. coli") and tag information if applicable .

What expression systems have been successfully used for POPTRDRAFT_820327?

POPTRDRAFT_820327 has been successfully expressed in both prokaryotic (E. coli) and eukaryotic (yeast) expression systems . The E. coli-expressed version is documented to include a His-tag, while the tag type for the yeast-expressed version is determined during the manufacturing process . Both systems appear to produce functional protein, though there may be differences in post-translational modifications between the two expression hosts. The choice between expression systems should be guided by the specific experimental requirements, with yeast potentially offering more plant-like post-translational modifications .

What purification methods are recommended for recombinant POPTRDRAFT_820327?

Based on the available commercial preparations, purification of POPTRDRAFT_820327 typically involves affinity chromatography utilizing the attached His-tag or other fusion tags . Researchers should implement a purification strategy that includes: (1) initial capture using affinity chromatography; (2) intermediate purification via ion exchange chromatography; and (3) polishing steps through size exclusion chromatography to achieve high purity. The commercial preparations report a purity level of >85% as determined by SDS-PAGE analysis . For laboratory-scale purification, consider including protease inhibitors during lysis to prevent degradation, and optimize buffer conditions to maintain protein stability throughout the purification process.

What are the optimal storage conditions for maintaining POPTRDRAFT_820327 stability?

The optimal storage conditions for POPTRDRAFT_820327 are at -20°C or -80°C, with the latter providing better long-term stability . The shelf life depends on formulation: liquid preparations typically remain stable for approximately 6 months, while lyophilized formulations maintain stability for up to 12 months . For working stocks, aliquots can be stored at 4°C for up to one week, but repeated freeze-thaw cycles should be strictly avoided as they significantly compromise protein integrity . The protein's stability is enhanced by the addition of glycerol (recommended at 5-50% final concentration) when stored in liquid form .

How should researchers reconstitute lyophilized POPTRDRAFT_820327 preparations?

To reconstitute lyophilized POPTRDRAFT_820327, first briefly centrifuge the vial to bring contents to the bottom . Reconstitute the protein in deionized sterile water to achieve a concentration of 0.1-1.0 mg/mL . For long-term storage, add glycerol to a final concentration of 5-50% (with 50% being commonly used as a default) . After reconstitution, divide the solution into small working aliquots to minimize freeze-thaw cycles. Document reconstitution date, concentration, and buffer composition on each aliquot. For critical experiments, verify protein activity after reconstitution to ensure functionality has been preserved.

What experimental approaches are recommended for determining the biological function of POPTRDRAFT_820327?

Given the limited published information on POPTRDRAFT_820327's specific function, researchers should employ multiple complementary approaches:

• Comparative genomic analysis: Align the sequence with characterized CASP-family proteins across species to identify conserved functional domains and predict potential roles .

• Subcellular localization studies: Express fluorescently-tagged POPTRDRAFT_820327 in plant cells to determine its localization pattern, which can provide insights into potential functions (e.g., cell membrane, endoplasmic reticulum, Golgi).

• Interaction studies: Perform yeast two-hybrid assays, co-immunoprecipitation, or pull-down assays to identify protein interaction partners, as these interactions may illuminate functional pathways .

• Loss-of-function and gain-of-function studies: Generate knockout or overexpression lines in model plant systems to observe resulting phenotypes.

• Gene expression analysis: Examine expression patterns under different environmental conditions, developmental stages, and in response to stressors.

These approaches should be conducted in parallel to build a comprehensive understanding of POPTRDRAFT_820327's biological role in Populus trichocarpa.

How can researchers investigate potential biological pathways involving POPTRDRAFT_820327?

To elucidate the biological pathways involving POPTRDRAFT_820327:

• Pathway reconstruction: Begin with bioinformatic prediction of pathways based on sequence homology with known CASP-family proteins, which are typically involved in cell wall formation and casparian strip development in plants .

• Transcriptomics approach: Perform RNA-Seq analysis comparing wild-type plants with those showing altered POPTRDRAFT_820327 expression to identify co-regulated genes.

• Metabolomics studies: Analyze metabolite profiles in plants with modified POPTRDRAFT_820327 expression to identify affected metabolic pathways.

• Proteomics analysis: Implement quantitative proteomics to identify proteins whose abundance changes in response to POPTRDRAFT_820327 manipulation.

• Functional complementation: Test whether POPTRDRAFT_820327 can functionally complement known CASP mutants in model plants like Arabidopsis to confirm hypothesized pathway involvement.

Document all experimental conditions meticulously, as slight variations may significantly impact pathway analysis results.

What methods are recommended for analyzing the structural properties of POPTRDRAFT_820327?

For comprehensive structural characterization of POPTRDRAFT_820327, consider the following methodological approaches:

• Secondary structure prediction: Utilize computational tools to predict alpha-helices, beta-sheets, and transmembrane domains based on the amino acid sequence.

• X-ray crystallography: Optimize crystallization conditions using purified protein to determine high-resolution three-dimensional structure. Initial screening should include varying protein concentrations (5-15 mg/mL), pH ranges (5.0-8.5), and different precipitants.

• Nuclear Magnetic Resonance (NMR) spectroscopy: For structural analysis in solution, especially useful for examining dynamic regions and protein-protein interactions.

• Circular Dichroism (CD) spectroscopy: To analyze secondary structure content and thermal stability under different buffer conditions.

• Cryo-electron microscopy: Particularly valuable if POPTRDRAFT_820327 forms larger complexes or if crystallization proves challenging.

• Limited proteolysis: To identify stable domains and flexible regions within the protein structure.

Combining these methods will provide a more complete structural understanding than any single approach alone.

What are the predicted structural features of POPTRDRAFT_820327 based on sequence analysis?

Based on sequence analysis of the 186 amino acid POPTRDRAFT_820327 protein, several structural features can be predicted:

• Transmembrane domains: The sequence contains hydrophobic regions consistent with transmembrane segments (residues approximately 19-39 and 120-140), suggesting a membrane-associated function .

• Signal peptide: The N-terminal region (approximately residues 1-18) displays characteristics of a signal peptide, indicating the protein likely enters the secretory pathway .

• Conserved motifs: The sequence contains regions consistent with the CASP (Casparian strip membrane domain protein) family, including the typical four transmembrane domain architecture .

• Post-translational modification sites: Potential glycosylation and phosphorylation sites can be predicted using computational tools, though experimental verification is necessary.

• Potential disulfide bonds: The presence of cysteine residues suggests possible disulfide bond formation that may stabilize the tertiary structure.

These predicted features align with the protein's classification as a CASP-like protein, which typically functions in the formation of diffusion barriers in plant cell walls.

What are effective protocols for studying POPTRDRAFT_820327 protein-protein interactions?

To investigate POPTRDRAFT_820327 protein-protein interactions:

• Yeast two-hybrid (Y2H): Clone the POPTRDRAFT_820327 coding sequence into both bait and prey vectors to identify potential interacting partners from a Populus trichocarpa cDNA library. Use both full-length protein and domain-specific constructs to pinpoint interaction regions .

• Pull-down assays: Express His-tagged POPTRDRAFT_820327 and use Ni-NTA resin to capture the protein along with its binding partners from plant cell lysates. Identify interacting proteins via mass spectrometry .

• Bimolecular Fluorescence Complementation (BiFC): Fuse POPTRDRAFT_820327 and candidate interaction partners to complementary fragments of fluorescent proteins to visualize interactions in living plant cells.

• Co-immunoprecipitation (Co-IP): Use antibodies specific to POPTRDRAFT_820327 or its epitope tag to precipitate protein complexes from plant extracts, followed by western blot or mass spectrometry analysis of co-precipitated proteins .

• Surface Plasmon Resonance (SPR) or Isothermal Titration Calorimetry (ITC): For quantitative analysis of binding affinities between purified POPTRDRAFT_820327 and candidate interacting proteins.

Document interaction strength, specificity, and the cellular context in which these interactions occur.

How can researchers effectively design experiments to study POPTRDRAFT_820327 expression patterns in plant tissues?

To comprehensively analyze POPTRDRAFT_820327 expression patterns:

• Quantitative RT-PCR: Design gene-specific primers spanning exon-exon junctions to quantify POPTRDRAFT_820327 transcript levels across different tissues, developmental stages, and environmental conditions.

• RNA in situ hybridization: Develop specific RNA probes to visualize spatial expression patterns within tissue sections, particularly useful for examining expression in specific cell types within complex tissues.

• Promoter-reporter fusion constructs: Clone the POPTRDRAFT_820327 promoter region (approximately 2kb upstream of the transcription start site) and fuse it to reporter genes such as GUS or GFP to track expression patterns in transgenic Populus lines.

• Immunohistochemistry: Generate specific antibodies against POPTRDRAFT_820327 or use epitope-tagged versions to detect protein localization in tissue sections.

• Single-cell RNA-Seq: For high-resolution analysis of expression patterns at the cellular level, particularly valuable for identifying cell type-specific expression.

Implement appropriate normalization methods and include sufficient biological replicates (minimum n=3) to account for natural variation in expression levels.

What is the recommended protocol for reconstitution and dilution of POPTRDRAFT_820327?

A standardized protocol for reconstitution and dilution of POPTRDRAFT_820327 includes:

• Preparation:

  • Centrifuge the vial briefly before opening to collect all material at the bottom

  • Allow lyophilized protein to reach room temperature before opening

• Reconstitution:

  • Reconstitute in deionized sterile water to achieve a concentration of 0.1-1.0 mg/mL

  • Gently rotate or invert the vial several times to ensure complete dissolution

  • Avoid vigorous vortexing which may cause protein denaturation

• Stabilization:

  • Add glycerol to a final concentration of 5-50% (with 50% being standard for long-term storage)

  • For experimental use, prepare working dilutions in appropriate buffers immediately before use

• Aliquoting:

  • Divide the reconstituted protein into single-use aliquots (typically 10-50 μL)

  • Use low-protein binding tubes to prevent loss through adsorption

  • Label each aliquot with concentration, date of reconstitution, and lot number

• Storage:

  • Store aliquots at -20°C for up to 6 months or -80°C for longer-term storage

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

This protocol maximizes protein stability and experimental reproducibility when working with POPTRDRAFT_820327.

What analytical methods are recommended for assessing the purity and integrity of POPTRDRAFT_820327 preparations?

To comprehensively evaluate POPTRDRAFT_820327 purity and integrity:

• SDS-PAGE analysis:

  • Run samples on 12-15% acrylamide gels due to the protein's size (186 amino acids)

  • Stain with Coomassie Blue for general protein detection or silver stain for higher sensitivity

  • Commercial preparations should show >85% purity by densitometry analysis

• Western blotting:

  • Use antibodies against the protein itself or its affinity tag (e.g., His-tag)

  • Assess both for the presence of the full-length protein and any degradation products

• Mass spectrometry:

  • MALDI-TOF or ESI-MS to confirm molecular weight

  • Peptide mass fingerprinting to verify sequence identity

  • Look for post-translational modifications that may affect functionality

• Size exclusion chromatography:

  • Analyze oligomeric state and detect potential aggregation

  • Use in combination with multi-angle light scattering (SEC-MALS) for precise molecular weight determination

• Dynamic light scattering (DLS):

  • Assess sample homogeneity and identify potential aggregation

  • Monitor protein stability over time and under different buffer conditions

These methods should be used in combination to ensure comprehensive quality assessment before proceeding with functional experiments.

How can researchers address poor expression or low solubility of recombinant POPTRDRAFT_820327?

When encountering poor expression or low solubility of POPTRDRAFT_820327:

• Optimization of expression conditions:

  • Test multiple expression temperatures (16°C, 25°C, 30°C, 37°C)

  • Vary induction timing and inducer concentration

  • Consider using specialized E. coli strains designed for membrane or difficult-to-express proteins

  • For yeast expression, test different growth media formulations and induction protocols

• Solubility enhancement strategies:

  • Test different fusion tags (MBP, GST, SUMO) which may enhance solubility compared to His-tag alone

  • Optimize lysis buffer composition by testing different detergents (DDM, CHAPS, Triton X-100) for this membrane-associated protein

  • Include stabilizing agents such as glycerol (5-10%) or low concentrations of reducing agents

• Refolding from inclusion bodies:

  • If the protein predominantly forms inclusion bodies, develop a refolding protocol

  • Solubilize inclusion bodies using 8M urea or 6M guanidine hydrochloride

  • Perform gradual dialysis to remove denaturant while adding stabilizing agents

• Co-expression with chaperones:

  • Co-express with molecular chaperones (GroEL/GroES, DnaK/DnaJ/GrpE) to aid proper folding

  • For eukaryotic expression systems, consider co-expression with plant-specific chaperones

• Alternative expression systems:

  • If E. coli and yeast systems yield poor results, consider plant-based expression systems which may provide the appropriate cellular environment for proper folding

Document all optimization attempts systematically to identify conditions that maximize protein yield and solubility.

What are the common pitfalls in experimental design when studying POPTRDRAFT_820327 and how can they be avoided?

Common experimental pitfalls when studying POPTRDRAFT_820327 and their solutions include:

• Protein degradation issues:

  • Pitfall: Rapid degradation during purification or storage

  • Solution: Add protease inhibitor cocktails during extraction, minimize handling time, and store with stabilizing agents such as glycerol

• Functionality assessment challenges:

  • Pitfall: Lack of established functional assays for CASP-like proteins

  • Solution: Develop multiple indirect assays based on predicted functions, including membrane integration assays, interaction studies with known cell wall components, and complementation of known CASP mutants

• Non-specific interactions:

  • Pitfall: False positive results in interaction studies

  • Solution: Include appropriate negative controls, validate interactions using multiple methodologies, and perform competition assays with unlabeled protein

• Expression system artifacts:

  • Pitfall: Post-translational modifications differ between expression systems and native context

  • Solution: Compare protein produced in different expression systems and validate findings using native protein extracted from Populus trichocarpa when possible

• Buffer compatibility issues:

  • Pitfall: Protein precipitation or inactivation in experimental buffers

  • Solution: Test protein stability in each experimental buffer before proceeding with functional assays; consider using native-like membrane environments for functional studies of this putative membrane protein

• Improper controls:

  • Pitfall: Inadequate control samples leading to misinterpretation

  • Solution: Include both positive controls (known CASP family proteins) and negative controls (unrelated proteins of similar size/properties) in all experiments

Systematic documentation of experimental conditions and regular quality control assessments will help identify and address these pitfalls early in the research process.

How should researchers approach comparative analysis between POPTRDRAFT_820327 and other CASP-like proteins?

To effectively compare POPTRDRAFT_820327 with other CASP-like proteins:

• Sequence alignment methodology:

  • Perform multiple sequence alignments using MUSCLE or CLUSTAL algorithms

  • Include well-characterized CASP proteins from model plants (Arabidopsis thaliana) and other woody species

  • Focus analysis on conserved domains and motifs characteristic of CASP family proteins

  • Generate phylogenetic trees using maximum likelihood or Bayesian methods to place POPTRDRAFT_820327 in evolutionary context

• Structural comparison approaches:

  • Use homology modeling based on available CASP protein structures

  • Compare predicted transmembrane topologies and domain organizations

  • Identify conserved residues that may be critical for function based on structural alignment

• Expression pattern comparison:

  • Compare tissue-specific and condition-responsive expression patterns between POPTRDRAFT_820327 and other CASP family members

  • Look for co-expression patterns that may indicate functional relationships

• Functional complementation experiments:

  • Test whether POPTRDRAFT_820327 can functionally replace other CASP proteins in heterologous systems

  • Document the degree of functional conservation or specialization within the family

This systematic comparative approach will help position POPTRDRAFT_820327 within the broader context of CASP protein biology and evolution.

What statistical methods are appropriate for analyzing experimental data related to POPTRDRAFT_820327?

When analyzing experimental data for POPTRDRAFT_820327:

• Expression data analysis:

  • Use ANOVA with post-hoc tests (Tukey's HSD, Bonferroni) for comparing expression levels across multiple conditions

  • Apply FDR correction for multiple testing when analyzing transcriptomic datasets

  • Implement principal component analysis (PCA) to identify patterns in multivariate expression data

• Protein-protein interaction analysis:

  • Calculate binding affinities (Kd values) from SPR or ITC data using appropriate binding models

  • Perform statistical comparison of interaction strengths using t-tests or non-parametric alternatives

  • For large-scale interaction studies, implement appropriate network analysis methods with significance testing

• Structural data analysis:

  • For CD spectroscopy data, use statistical deconvolution algorithms to estimate secondary structure content

  • Implement bootstrap methods to assess the reliability of structural predictions

  • For crystallography data, evaluate model quality using R-factors and geometric validation statistics

• Functional assay analysis:

  • Use dose-response curves and EC50/IC50 calculations where appropriate

  • Implement linear or non-linear regression models for analyzing kinetic data

  • For phenotypic studies, use appropriate categorical statistical methods and survival analysis where applicable

• Sample size and power considerations:

  • Conduct a priori power analysis to determine adequate sample sizes

  • Report effect sizes along with p-values

  • Consider using Bayesian statistical approaches for small sample sizes

Document all statistical methods, software packages, and parameters used to ensure reproducibility of analyses.