Recombinant Populus trichocarpa CASP-like protein POPTRDRAFT_752786 (POPTRDRAFT_752786)

What is POPTRDRAFT_752786 and what is its role in Populus trichocarpa?

POPTRDRAFT_752786 is a CASP-like protein found in Populus trichocarpa (Western balsam poplar), also known as PtCASPL1F3. CASP-like proteins are structurally related to Casparian Strip membrane domain proteins, which are typically involved in forming diffusion barriers in plant tissues. In P. trichocarpa, this protein likely plays a role in cell wall organization and potentially in symbiotic relationships with mycorrhizal fungi. The protein consists of 193 amino acids and contains transmembrane domains characteristic of CASP family proteins .

How is recombinant POPTRDRAFT_752786 typically produced for research applications?

Recombinant POPTRDRAFT_752786 is typically produced in E. coli expression systems with an N-terminal His-tag for purification purposes. The full-length protein (amino acids 1-193) is expressed and then purified using affinity chromatography, taking advantage of the His-tag. The purified protein is commonly supplied as a lyophilized powder with greater than 90% purity as determined by SDS-PAGE. For research applications, it's recommended to reconstitute the protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL, adding 5-50% glycerol for long-term storage at -20°C/-80°C .

What are the optimal storage and handling conditions for recombinant POPTRDRAFT_752786?

To maintain the structural integrity and activity of recombinant POPTRDRAFT_752786, follow these research-validated protocols:

• Upon receipt, briefly centrifuge the vial to bring contents to the bottom

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

• Add glycerol to a final concentration of 5-50% (50% is standard) to prevent freeze-thaw damage

• Aliquot the protein solution to minimize freeze-thaw cycles

• Store working aliquots at 4°C for up to one week

• Store long-term aliquots at -20°C/-80°C

• Avoid repeated freeze-thaw cycles as they can lead to protein denaturation and loss of function

The protein is typically supplied in a Tris/PBS-based buffer containing 6% trehalose at pH 8.0, which helps maintain stability during lyophilization and reconstitution .

How can I verify the purity and integrity of recombinant POPTRDRAFT_752786 before using it in experiments?

To ensure experimental reproducibility, validate your recombinant POPTRDRAFT_752786 preparation through:

• SDS-PAGE analysis: Run the protein on a 10-15% gel to confirm the expected molecular weight (~21 kDa plus His-tag) and assess purity (should be >90%)

• Western blotting: Use anti-His antibodies to confirm the presence of the His-tagged protein

• Mass spectrometry: For precise molecular weight determination and to verify the complete amino acid sequence

• Circular dichroism (CD): To evaluate proper protein folding and secondary structure

• Size exclusion chromatography: To assess aggregation state and homogeneity

Commercial preparations typically undergo quality control with SDS-PAGE to ensure >90% purity, but additional validation is recommended for critical experiments to confirm structural integrity after reconstitution .

What methodological approaches can be used to study the interaction of POPTRDRAFT_752786 with other proteins?

To investigate protein-protein interactions involving POPTRDRAFT_752786, consider these methodological approaches:

• Co-immunoprecipitation (Co-IP): Using anti-His antibodies to pull down POPTRDRAFT_752786 and identify interacting partners by mass spectrometry

• Yeast two-hybrid (Y2H) screening: For identifying potential binding partners from a Populus trichocarpa cDNA library

• Bimolecular fluorescence complementation (BiFC): To visualize interactions in planta by fusing protein fragments to POPTRDRAFT_752786 and potential interactors

• Surface plasmon resonance (SPR): For quantitative measurement of binding kinetics and affinities

• Protein pull-down assays: Using the His-tagged POPTRDRAFT_752786 as bait with plant extracts

• Isothermal titration calorimetry (ITC): For thermodynamic characterization of binding interactions

When designing these experiments, it's important to consider the transmembrane nature of CASP-like proteins, which may require detergent-based buffers or membrane mimetics to maintain proper folding and function .

How is POPTRDRAFT_752786 expression regulated in Populus trichocarpa?

While specific expression data for POPTRDRAFT_752786 is limited in the provided search results, research on other Populus trichocarpa genes indicates complex regulation patterns, particularly during symbiotic interactions. Similar to other plant proteins involved in symbiosis, POPTRDRAFT_752786 expression is likely regulated by:

• Developmental cues in different root tissues

• Environmental factors, particularly nutrient availability

• Presence of symbiotic partners like ectomycorrhizal fungi

For example, other P. trichocarpa genes show dramatic expression changes during interaction with Laccaria bicolor, with some genes being upregulated more than 10,000-fold under specific conditions. Quantitative RT-PCR analysis would be an appropriate method to determine POPTRDRAFT_752786 expression patterns under different conditions, with RNA-seq providing a more comprehensive view of expression in the context of the whole transcriptome .

What techniques are most effective for studying POPTRDRAFT_752786 expression in different tissues?

To effectively study POPTRDRAFT_752786 expression across Populus tissues, researchers should consider:

• RNA sequencing (RNA-seq): For comprehensive transcriptome-wide analysis and quantification of expression levels across different tissues or conditions

• Quantitative RT-PCR: For targeted validation of expression patterns with high sensitivity (shown to correlate significantly with RNA-seq data in Populus studies)

• In situ hybridization: To localize mRNA expression to specific cell types within tissues

• Promoter-reporter fusion assays: Using the POPTRDRAFT_752786 promoter fused to reporters like GFP or GUS to visualize expression patterns in transgenic poplar

• Laser capture microdissection: Combined with qRT-PCR or RNA-seq for cell-type specific expression analysis

When analyzing expression data, it's important to normalize appropriately using stable reference genes validated for Populus tissues and to compare expression patterns with phylogenetically related CASP-like proteins to identify functional relationships .

How does symbiotic association with mycorrhizal fungi affect POPTRDRAFT_752786 expression?

Based on studies of P. trichocarpa's interaction with the ectomycorrhizal fungus Laccaria bicolor, many plant proteins show significant regulation during symbiosis. While specific data for POPTRDRAFT_752786 isn't provided, the pattern observed with other P. trichocarpa small secreted proteins (SSPs) suggests that:

• SSPs can be significantly upregulated during mycorrhizal symbiosis

• Some P. trichocarpa SSPs can enter fungal hyphae and affect hyphal growth and morphology

• Expression patterns may differ between strong ECM host plants (like P. trichocarpa) and poor ECM host plants (like P. deltoides)

To study POPTRDRAFT_752786 regulation during symbiosis, researchers should establish controlled mycorrhizal colonization experiments and analyze gene expression at different stages of the interaction using RNA-seq or qRT-PCR. Comparison between different Populus species with varying mycorrhizal compatibility would provide insights into the protein's role in symbiotic establishment .

What structural features of POPTRDRAFT_752786 are important for its function?

POPTRDRAFT_752786, as a CASP-like protein, likely contains several key structural features important for its function:

• Transmembrane domains: The amino acid sequence indicates multiple transmembrane regions, characteristic of CASP family proteins

• Signal peptide: The N-terminal portion likely contains a signal peptide directing the protein to the cell membrane

• Conserved domains: Specific protein domains may be involved in protein-protein interactions or membrane localization

Computational analysis of the amino acid sequence using tools like TMHMM (transmembrane prediction), SignalP (signal peptide prediction), and comparison with other characterized CASP proteins can help identify these features. Experimental approaches like site-directed mutagenesis of specific residues followed by functional assays would help validate the importance of these structural elements .

How can I determine if POPTRDRAFT_752786 interacts with fungal proteins during mycorrhizal symbiosis?

To investigate potential interactions between POPTRDRAFT_752786 and fungal proteins during mycorrhizal symbiosis, consider this methodological workflow:

• Fluorescent labeling experiments: Tag POPTRDRAFT_752786 with FITC or HA and test its ability to enter fungal hyphae (similar to experiments conducted with other P. trichocarpa SSPs)

• Localization studies: If the protein enters fungal cells, determine its subcellular localization (e.g., nucleus, cytoplasm)

• Protein scrambling experiments: Create versions with scrambled amino acid sequences to test if specific sequence motifs are required for fungal entry

• Co-immunoprecipitation with crosslinking: To capture transient interactions between the plant protein and fungal targets

• Yeast two-hybrid screening: Using POPTRDRAFT_752786 as bait against a cDNA library from Laccaria bicolor

• Functional assays: Measure the effect of purified recombinant POPTRDRAFT_752786 on hyphal growth and morphology

Research with other P. trichocarpa SSPs has shown that some can enter L. bicolor hyphae, localize to the nucleus, and affect hyphal growth, suggesting a potential effector-like function. Similar approaches could reveal whether POPTRDRAFT_752786 has comparable capabilities .

What pathways and biological processes is POPTRDRAFT_752786 potentially involved in?

Based on its classification as a CASP-like protein and evidence from related proteins, POPTRDRAFT_752786 is potentially involved in:

• Cell wall organization: CASP proteins typically function in forming diffusion barriers in plant tissues

• Nutrient transport regulation: Possibly controlling movement of minerals and water across cell barriers

• Symbiotic interfaces: Potentially functioning at the interface between plant and fungal cells during mycorrhizal symbiosis

• Root development: CASP proteins often play roles in specialized root structures

While specific pathway information for POPTRDRAFT_752786 is not directly mentioned in the search results, studies of P. trichocarpa's interaction with ectomycorrhizal fungi suggest potential roles in symbiotic processes. Transcriptomic studies combined with GO (Gene Ontology) enrichment analysis would help identify the biological processes associated with POPTRDRAFT_752786 expression .

How does POPTRDRAFT_752786 compare to similar proteins in other plant species?

A comparative analysis of POPTRDRAFT_752786 with related proteins should consider:

• Phylogenetic relationships: Construct phylogenetic trees with CASP-like proteins from diverse plant species to determine evolutionary relationships

• Sequence conservation: Identify highly conserved motifs across species that may indicate functional importance

• Species-specific adaptations: Determine if POPTRDRAFT_752786 contains unique features specific to Populus or woody perennials

The search results indicate that some P. trichocarpa SSPs appear to be specific to Populus (without homologs in other examined species), while others have homologs only in closely related plant genera. A comparison between P. trichocarpa (strong ECM host) and P. deltoides (poor ECM host) showed that some SSPs present in P. trichocarpa were missing or truncated in P. deltoides, suggesting potential importance in mycorrhizal compatibility. Similar comparative analysis for POPTRDRAFT_752786 would provide insights into its evolutionary and functional significance .

Are there significant differences in POPTRDRAFT_752786 between Populus trichocarpa and other Populus species?

Research comparing different Populus species has revealed important genetic differences that may affect protein function and symbiotic capabilities:

• Some P. trichocarpa small secreted proteins are missing or truncated in P. deltoides accessions

• These differences correlate with the observation that P. trichocarpa is a strong ectomycorrhizal (ECM) host while P. deltoides is a poor ECM host

To determine if similar differences exist for POPTRDRAFT_752786:

• Compare the sequence between P. trichocarpa accessions (Nisqually-1 and 93-960) and P. deltoides accessions (ILL-101 and D124)

• Analyze the promoter regions for differences that might affect expression patterns

• Conduct functional complementation studies to determine if differences affect protein function

Such comparative analysis could provide insights into whether POPTRDRAFT_752786 contributes to the differential mycorrhizal hosting capabilities observed between Populus species .

How do expression patterns of POPTRDRAFT_752786 compare across different Populus genotypes under varying environmental conditions?

While specific POPTRDRAFT_752786 expression data across genotypes isn't provided, research on other P. trichocarpa genes reveals significant variation in expression patterns between species and under different conditions:

To study POPTRDRAFT_752786 expression patterns:

• Design qRT-PCR primers specific to POPTRDRAFT_752786

• Compare expression across different Populus genotypes (P. trichocarpa, P. deltoides, hybrids)

• Test under various conditions (nutrient availability, mycorrhizal colonization, drought stress)

• Validate findings with RNA-seq for genome-wide context

Understanding these expression patterns would provide insights into the protein's potential roles and regulation mechanisms across Populus species .

How can CRISPR-Cas9 gene editing be used to study POPTRDRAFT_752786 function in Populus trichocarpa?

A comprehensive CRISPR-Cas9 based strategy to study POPTRDRAFT_752786 function would include:

• Gene knockout: Design sgRNAs targeting unique regions of POPTRDRAFT_752786 to create null mutants

• Domain-specific mutations: Create targeted modifications to specific functional domains rather than complete knockouts

• Promoter editing: Modify the native promoter to alter expression patterns

• Tagging: Insert reporter genes (GFP, mCherry) in-frame to study subcellular localization

• Multiplex editing: Target multiple CASP-like family members simultaneously to address functional redundancy

The transformation protocol should be optimized for Populus, typically using Agrobacterium-mediated transformation of stem segments or leaf discs, followed by callus induction and plant regeneration. Phenotypic analysis should focus on:

• Root development and architecture

• Casparian strip formation

• Nutrient uptake efficiency

• Mycorrhizal colonization rates

• Transcriptomic changes in response to symbiotic fungi

This approach would provide definitive evidence of POPTRDRAFT_752786's functional role in Populus development and symbiotic interactions .

What approaches can resolve contradictory data about POPTRDRAFT_752786 localization and function?

When faced with contradictory data about POPTRDRAFT_752786 localization or function, implement this systematic troubleshooting framework:

• Methodological validation:

  • Compare protein localization using multiple tagging approaches (N-terminal vs. C-terminal tags)

  • Verify tag position doesn't interfere with trafficking signals

  • Use both transient and stable transformation systems

• Context-dependent analysis:

  • Test localization under varying developmental stages

  • Examine effects of environmental conditions (nutrient availability, stress)

  • Compare results in different genetic backgrounds

• Resolution strategies:

  • Super-resolution microscopy for precise subcellular localization

  • Subcellular fractionation combined with immunoblotting

  • Time-course studies to capture dynamic relocalization

  • Simultaneous visualization of multiple cellular compartments

• Functional validation:

  • Complement knockout lines with wild-type and mutated versions

  • Perform domain swapping with related proteins

  • Use inducible expression systems to control timing of expression

This systematic approach would help resolve contradictory findings and provide a more complete understanding of POPTRDRAFT_752786's dynamic functions in different contexts .

How can high-throughput sequencing approaches be used to identify genome-wide interactions of POPTRDRAFT_752786?

To identify genome-wide interactions and regulatory networks involving POPTRDRAFT_752786, implement these advanced sequencing approaches:

• ChIP-seq (if DNA-binding activity is suspected):

  • Create transgenic Populus expressing tagged POPTRDRAFT_752786

  • Perform chromatin immunoprecipitation followed by sequencing

  • Identify potential DNA binding sites and regulated genes

• RNA-seq comparative analysis:

  • Compare transcriptomes of wild-type and POPTRDRAFT_752786 knockout/overexpression lines

  • Identify differentially expressed genes in various tissues and conditions

  • Construct co-expression networks to identify functionally related genes

• Ribosome profiling:

  • Assess translational impacts of POPTRDRAFT_752786 manipulation

  • Identify changes in ribosome occupancy on mRNAs

• Proximity-dependent biotin labeling (BioID or TurboID):

  • Fuse POPTRDRAFT_752786 with a biotin ligase

  • Identify proximal proteins in living cells

  • Map the protein interaction network

• ATAC-seq:

  • Assess chromatin accessibility changes in response to POPTRDRAFT_752786 manipulation

  • Identify potential regulatory regions affected

These approaches would provide a comprehensive understanding of POPTRDRAFT_752786's role in cellular processes and regulatory networks, moving beyond single-gene studies to system-level insights .