Recombinant Vitis vinifera CASP-like protein VIT_10s0092g00220 (VIT_10s0092g00220)

What is VIT_10s0092g00220 and where is it expressed in Vitis vinifera?

VIT_10s0092g00220 is a CASP-like protein from Vitis vinifera (grape), also known as VvCASPL1B2 or CASP-like protein 1B2. It belongs to the family of Casparian Strip Membrane Domain Proteins (CASPs) that are primarily characterized by their four-transmembrane structure . While specific expression data for VIT_10s0092g00220 in Vitis vinifera is limited in the provided context, studies on related CASPL proteins suggest potential expression in vascular tissues. The protein contains 204 amino acids and has been successfully expressed as a recombinant protein with an N-terminal His tag in E. coli for research purposes .

What are the key structural determinants for CASP-like protein localization and function?

Structural analyses of CASP and CASP-like proteins have revealed several key determinants critical for their proper localization and function. The transmembrane domains appear particularly important for scaffold formation and membrane localization. Notably, mutagenesis experiments with AtCASP1 showed that a conserved Asp residue in TM3 (equivalent to D134H in AtCASP1) is essential for correct protein folding, as mutations at this position prevented detectable protein expression .

Interestingly, while the extracellular loops contain conserved regions, deletion experiments demonstrated that these loops are not absolutely required for localization to the Casparian strip membrane domain (CSD). When either the first extracellular loop (EL1) or the second extracellular loop (EL2) was deleted from AtCASP1, the protein was still able to localize to the CSD, although with altered dynamics. Deletions of EL1 resulted in longer persistence at lateral membranes and delayed enrichment at the CSD, while deletion of EL2 led to faster signal fading at the CSD .

How might the evolutionarily conserved residues in VIT_10s0092g00220 contribute to its functional specialization?

Evolutionary analysis of CASP and CASP-like proteins has identified several conserved motifs that likely contribute to functional specialization. Of particular interest is a nine-amino acid signature (ESLPFFTQF) found in the first extracellular loop (EL1) of CASP proteins in spermatophytes, which is absent in bryophytes and lycophytes that lack Casparian strips . Although the exact function of this signature remains to be fully elucidated, its conservation suggests a role in endodermis-specific functions.

For VIT_10s0092g00220, comparative sequence analysis with other CASPLs would reveal whether it contains similarly conserved residues that might determine its subcellular localization and functional properties. Understanding these conservation patterns could provide insights into how CASP-like proteins have evolved specialized functions across different plant species and tissues .

How does VIT_10s0092g00220 compare to other characterized CASP-like proteins in terms of cold stress response?

While specific data on VIT_10s0092g00220's response to cold stress is not directly provided in the search results, insights can be gained from studies on other CASP-like proteins. Research on a cold-induced CASP-like protein from watermelon (ClCASPL) and its Arabidopsis ortholog (AtCASPL4C1) revealed significant roles in cold stress tolerance .

Expression analysis showed that AtCASPL4C1 is cold-inducible, and knockout plants exhibited elevated tolerance to cold stress. Conversely, overexpression of ClCASPL in Arabidopsis resulted in increased sensitivity to cold stress. These findings suggest that some CASP-like proteins function as negative regulators of cold tolerance .

To determine whether VIT_10s0092g00220 plays a similar role in grapevine, researchers would need to investigate its expression patterns under cold stress conditions and perform functional studies through overexpression or silencing approaches.

What are the optimal conditions for expression and purification of recombinant VIT_10s0092g00220?

For optimal expression and purification of recombinant VIT_10s0092g00220, researchers should consider the following protocol based on existing practices for this protein:

Expression System:

• E. coli is the preferred expression system for VIT_10s0092g00220

• Expression construct should include the full-length protein (residues 1-204) with an N-terminal His tag for purification

Purification Protocol:

• Express the protein in E. coli using standard induction protocols

• Lyse cells under appropriate buffer conditions

• Purify using affinity chromatography (Ni-NTA or similar resin for His-tagged proteins)

• Elute in Tris/PBS-based buffer, pH 8.0

• Add 6% Trehalose to stabilize the protein

• Lyophilize for long-term storage

Reconstitution Guidelines:

• Centrifuge the vial briefly before opening

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

• Add glycerol to 5-50% final concentration (50% recommended)

• Aliquot and store at -20°C/-80°C

• Avoid repeated freeze-thaw cycles

What approaches can be used to investigate membrane localization and domain formation of VIT_10s0092g00220?

To investigate membrane localization and domain formation of VIT_10s0092g00220, researchers can employ several complementary approaches:

Fluorescent Protein Fusion and Microscopy:

• Generate C- or N-terminal GFP/mCherry fusions of VIT_10s0092g00220

• Express in heterologous systems (e.g., Arabidopsis, tobacco) or homologous Vitis systems

• Perform confocal microscopy to track subcellular localization

• Use time-lapse imaging to monitor protein dynamics and membrane domain formation

Co-localization Studies:

• Co-express VIT_10s0092g00220-GFP with established membrane domain markers

• Perform immunolocalization with domain-specific antibodies

• Use FRET/FLIM to investigate protein-protein interactions in membrane domains

Deletion and Mutagenesis Analysis:

• Create deletion variants lacking specific domains (e.g., extracellular loops)

• Mutate conserved residues in transmembrane domains

• Assess effects on localization and domain formation through microscopy

Biochemical Fractionation:

• Isolate membrane fractions through differential centrifugation

• Perform detergent resistance assays to identify membrane microdomain association

• Use immunoblotting to detect protein in different subcellular fractions

How can functional complementation assays be designed to assess VIT_10s0092g00220 activity?

Functional complementation assays provide valuable insights into protein function by determining if a protein can rescue mutant phenotypes. For VIT_10s0092g00220, the following complementation strategies could be employed:

Heterologous Complementation in Arabidopsis:

• Identify Arabidopsis CASPL mutants with clear phenotypes (e.g., AtCASPL4C1 knockout)

• Generate expression constructs with VIT_10s0092g00220 under native or constitutive promoters

• Transform these constructs into the mutant background

• Assess rescue of phenotypes such as:

  • Growth parameters (biomass, flowering time)

  • Cold stress tolerance

  • Casparian strip formation (if applicable)

Promoter Analysis and Expression Studies:

• Clone the native promoter of VIT_10s0092g00220

• Fuse to reporter genes (GUS or fluorescent proteins)

• Generate transgenic plants and analyze expression patterns

• Compare with expression patterns of known CASPL genes to infer function

Domain Swap Experiments:

• Create chimeric proteins by swapping domains between VIT_10s0092g00220 and well-characterized CASP/CASPL proteins

• Express in appropriate mutant backgrounds

• Assess which domains are sufficient for functional complementation

How can researchers distinguish between Casparian strip-related and alternative functions of VIT_10s0092g00220?

Distinguishing between Casparian strip-related and alternative functions requires multiple experimental approaches:

Tissue-Specific Expression Analysis:

• Perform detailed expression profiling across tissues and developmental stages using:

  • RT-qPCR

  • Promoter-reporter constructs (e.g., pVIT_10s0092g00220:GUS)

  • In situ hybridization

• Compare expression patterns with known Casparian strip-specific genes

• Identify tissues expressing VIT_10s0092g00220 that lack Casparian strips

Phenotypic Analysis Beyond Casparian Strips:

• Generate knockout/knockdown lines in appropriate model systems

• Assess diverse phenotypes beyond root endodermis:

  • Vascular development

  • Abiotic stress responses (particularly cold stress)

  • Growth parameters and developmental timing

  • Cell wall properties in multiple tissues

Subcellular Localization Studies:

• Compare localization patterns with canonical CASP proteins

• Identify unique localization patterns in non-endodermal cells

• Analyze co-localization with other membrane domain markers

Interaction Partner Identification:

• Perform co-immunoprecipitation followed by mass spectrometry

• Use yeast two-hybrid or split-ubiquitin assays for membrane proteins

• Compare interactome with known CASP protein interactors

What potential roles might VIT_10s0092g00220 play in abiotic stress responses in Vitis vinifera?

Based on studies of related CASP-like proteins, VIT_10s0092g00220 may have significant roles in abiotic stress responses in Vitis vinifera:

Cold Stress Response:
Studies on ClCASPL (from watermelon) and AtCASPL4C1 (from Arabidopsis) revealed important functions in cold stress response. AtCASPL4C1 knockout plants showed enhanced cold tolerance, while ClCASPL overexpression increased cold sensitivity, suggesting these proteins function as negative regulators of cold tolerance mechanisms .

Potential Mechanisms:

• Plasma membrane remodeling during temperature fluctuations

• Regulation of ion/water transport under stress conditions

• Modulation of cell wall properties affecting stress resilience

• Signaling pathway involvement through protein-protein interactions

Experimental Approaches to Investigate:

• Expression analysis under various abiotic stresses (cold, drought, salt)

• Generation of transgenic grapevines with altered VIT_10s0092g00220 expression

• Phenotypic evaluation under controlled stress conditions

• Comparative transcriptomics and metabolomics to identify affected pathways

What techniques can be used to investigate protein-protein interactions involving VIT_10s0092g00220?

Investigating protein-protein interactions for membrane-localized proteins like VIT_10s0092g00220 requires specialized techniques:

Membrane-Based Yeast Two-Hybrid:

• Split-ubiquitin yeast two-hybrid system specifically designed for membrane proteins

• MYTH (Membrane Yeast Two-Hybrid) screening against cDNA libraries

• Directed testing against predicted interaction partners

Co-Immunoprecipitation:

• Generate transgenic plants expressing tagged VIT_10s0092g00220

• Perform membrane protein extraction with appropriate detergents

• Immunoprecipitate using tag-specific antibodies

• Identify co-precipitating proteins by mass spectrometry

Fluorescence-Based Interaction Assays:

• Bimolecular Fluorescence Complementation (BiFC)

• Förster Resonance Energy Transfer (FRET)

• Fluorescence Lifetime Imaging Microscopy (FLIM)

• Proximity Ligation Assay (PLA) for in situ detection of interactions

Cross-Linking Mass Spectrometry:

• Use membrane-permeable crosslinkers to stabilize transient interactions

• Perform affinity purification of cross-linked complexes

• Analyze by mass spectrometry to identify interaction partners and interfaces

• Validate key interactions through directed assays

How does the structure and function of VIT_10s0092g00220 compare across different plant species?

Comparative analysis of VIT_10s0092g00220 homologs across plant species provides insights into structural and functional conservation:

Phylogenetic Distribution:
CASP-like proteins are found throughout land plants and green algae, with homologs outside plants belonging to the MARVEL protein family. This broad distribution suggests ancient origins and potentially conserved core functions .

Structural Conservation:
The four-transmembrane structure is highly conserved among CASP-like proteins. Specific conserved residues, particularly in transmembrane domains, likely contribute to membrane scaffold formation. The second extracellular loop (EL2) shows conservation among CASPLs, while the first extracellular loop (EL1) is more variable .

Functional Diversification:
While the membrane scaffold function appears conserved, CASP-like proteins show functional diversification:

• Some are involved in Casparian strip formation (e.g., CASP1-5)

• Others play roles in abiotic stress responses (e.g., AtCASPL4C1)

• Some may function in vascular tissue development

• Certain members may regulate growth and developmental timing

Comparative Approaches:

• Sequence alignment and phylogenetic analysis

• Heterologous expression studies

• Complementation assays across species

• Domain swapping between homologs to identify functionally important regions

What evolutionary patterns can be observed in the CASP-like protein family that might inform functional studies?

Evolutionary analysis of CASP-like proteins reveals several patterns with functional implications:

Emergence of Specialized Signatures:
A notable evolutionary pattern is the emergence of a nine-amino acid signature (ESLPFFTQF) in the first extracellular loop of CASP proteins in spermatophytes, which coincides with the appearance of Casparian strips. This signature is absent in bryophytes and lycophytes that lack Casparian strips, suggesting a role in specialized endodermal function .

Expansion Patterns:
The CASP-like family has undergone differential expansion across plant lineages, with varying numbers of members in different subgroups. This pattern suggests subfunctionalization and neofunctionalization events during plant evolution .

Conservation of Regulatory Elements:
Studies have shown conservation of regulatory elements across species. For example, a 2-kb genomic fragment upstream of a Lotus japonicus CASP gene was sufficient to drive endodermis-specific expression in Arabidopsis, indicating conservation of regulatory mechanisms across distantly related species .

Experimental Applications:

• Identify conserved motifs specific to functional subgroups

• Use evolutionary conservation patterns to predict functional domains

• Target highly conserved residues for mutagenesis

• Infer potential functions based on evolutionary relationships

What methodological approaches can be used to study the role of VIT_10s0092g00220 in vascular tissue development?

Since CASP-like proteins may have roles beyond Casparian strip formation, potentially in vascular tissue, the following approaches can be used to investigate VIT_10s0092g00220's role in vascular development:

Expression Analysis in Vascular Tissues:

• Generate transgenic plants with promoter-reporter constructs (e.g., pVIT_10s0092g00220:GUS)

• Perform high-resolution expression analysis in developing vascular tissues

• Use laser capture microdissection coupled with RT-qPCR for tissue-specific expression analysis

• Employ single-cell RNA-seq to identify cell types expressing VIT_10s0092g00220

Genetic Manipulation Approaches:

• Generate knockout/knockdown lines using CRISPR/Cas9 or RNAi

• Create tissue-specific expression lines using vascular-specific promoters

• Develop inducible expression systems to study temporal requirements

• Analyze effects on vascular development using histological and microscopy techniques

Physiological and Functional Assays:

• Assess vascular transport efficiency (e.g., dye transport assays)

• Analyze xylem and phloem development and differentiation

• Measure hydraulic conductivity and flow rates

• Examine responses to vascular stress conditions (e.g., embolism, wounding)

Comparative Developmental Studies:

• Compare vascular development in wild-type and modified lines

• Analyze expression during key developmental transitions

• Perform time-course studies during vascular differentiation

• Use reporter constructs to track dynamic changes in vascular tissues