Recombinant Vitis vinifera CASP-like protein VIT_07s0104g01350 (VIT_07s0104g01350)

What is the structure and function of CASP-like proteins in Vitis vinifera?

CASP-like proteins in Vitis vinifera, including VIT_07s0104g01350, are predicted to be four-membrane-span proteins that share structural similarities with the broader CASPL family. These proteins contain two extracellular loops (EL1 and EL2) with varying degrees of conservation . The function of CASPL proteins appears to be related to the formation of specialized membrane domains and potentially localized cell wall modifications.

Methodology for structural analysis:

• Generate recombinant constructs with varying truncations or domain swaps

• Perform protein modeling based on conserved domains identified in characterized CASP proteins

• Use site-directed mutagenesis targeting conserved residues, particularly the critical Asp residue in the third transmembrane domain (TM3) which has been shown to be essential for correct protein folding in related CASPs

• Employ circular dichroism spectroscopy to analyze secondary structure elements

How does VIT_07s0104g01350 relate to other characterized plant membrane domain proteins?

VIT_07s0104g01350 belongs to the CASPL protein family found across land plants and green algae. Homologs outside the plant kingdom have been identified as members of the MARVEL protein family . The relationship between VIT_07s0104g01350 and other membrane domain proteins can be established through:

• Phylogenetic analysis using multiple sequence alignment of transmembrane domains

• Comparative expression profiling across different plant tissues

• Functional complementation assays in Arabidopsis casp mutants

• Investigation of conserved motifs, particularly in the transmembrane regions

Research has shown that when ectopically expressed in the endodermis, most CASPLs demonstrated the ability to integrate into the CASP membrane domain, suggesting they share with CASPs the propensity to form transmembrane scaffolds . This property might be conserved in VIT_07s0104g01350, indicating a fundamental role in membrane organization.

What expression patterns would be expected for VIT_07s0104g01350 in different Vitis species?

Expression patterns of CASP-like proteins vary across tissues and developmental stages. For VIT_07s0104g01350, researchers should consider:

• Comparative transcriptome analysis across different Vitis species (V. vinifera, V. riparia, V. californica, V. amurensis)

• Tissue-specific expression profiling using quantitative RT-PCR

• Promoter analysis to identify regulatory elements controlling expression

• Generation of promoter-reporter constructs to visualize spatial expression patterns

Based on studies of other CASP family members, expression may be tissue-specific, with some CASPs predominantly expressed in the endodermis . The conservation of regulatory elements across Vitis species may indicate functional importance, as demonstrated by the ability of a 2-kb genomic fragment upstream of a Lotus japonicus CASP gene to drive expression in Arabidopsis endodermis .

How do environmental stresses affect VIT_07s0104g01350 expression?

Environmental stresses may modulate the expression of CASP-like proteins as part of plant adaptation responses. Methodological approaches to investigate this include:

• Exposure of Vitis tissue to various stresses (drought, salinity, temperature extremes)

• Treatment with defense elicitors such as benzothiadiazole (a salicylic acid analog)

• Time-course expression analysis during pathogen infection

• Comparison of expression responses between resistant and susceptible Vitis varieties

What techniques are most effective for recombinant expression and purification of VIT_07s0104g01350?

Membrane proteins like VIT_07s0104g01350 present unique challenges for recombinant expression and purification. Researchers should consider:

• Expression systems:

  • Prokaryotic systems (E. coli BL21(DE3), C41(DE3), C43(DE3))

  • Eukaryotic systems (Pichia pastoris, insect cells)

  • Plant-based expression (Nicotiana benthamiana agroinfiltration)

• Fusion strategies:

  • N-terminal vs. C-terminal tags based on predicted topology

  • Solubility-enhancing tags (MBP, SUMO, TrxA)

  • Fluorescent protein fusions for localization and folding assessment

• Purification optimization:

  • Detergent screening (DDM, LMNG, LDAO)

  • Lipid nanodisc reconstitution

  • On-column refolding protocols

Transient expression in Nicotiana benthamiana has proven successful for studying other Vitis proteins, such as VvNPR1.1-GFP and VvNPR1.2-GFP fusion proteins, which localized predominantly to the nucleus when expressed in this system .

How can protein-protein interactions of VIT_07s0104g01350 be effectively studied?

Understanding the interactome of VIT_07s0104g01350 is crucial for elucidating its function. Methodological approaches include:

• Membrane-based yeast two-hybrid (MYTH) system

• Split-ubiquitin assays optimized for membrane proteins

• Co-immunoprecipitation followed by mass spectrometry

• Bimolecular fluorescence complementation (BiFC) in planta

• Proximity-dependent biotin identification (BioID) or APEX2 proximity labeling

These techniques should be optimized for membrane proteins, with careful consideration of detergent conditions and membrane environment preservation during isolation procedures.

What role might VIT_07s0104g01350 play in grapevine defense against pathogens?

Investigating the potential role of VIT_07s0104g01350 in pathogen defense requires multiple approaches:

• Expression analysis during infection with common grapevine pathogens:

  • Plasmopara viticola (downy mildew)

  • Erysiphe necator (powdery mildew)

  • Botrytis cinerea (gray mold)

• Functional studies:

  • Generation of transgenic grapevines overexpressing VIT_07s0104g01350

  • RNA interference or CRISPR-Cas9 knockout/knockdown studies

  • Heterologous expression in model plants followed by pathogen challenge

• Biochemical analyses:

  • Investigation of potential roles in lignification or suberin deposition

  • Analysis of interaction with known defense signaling components

Research on VvNPR1.1 and VvNPR1.2 has shown that overexpression of these proteins enhances grapevine defensive capabilities upon fungal infection . If VIT_07s0104g01350 plays a role in forming specialized membrane domains that facilitate defense responses, similar approaches could reveal its contribution to pathogen resistance.

How does the membrane localization of VIT_07s0104g01350 compare across different Vitis species?

Comparative analysis of VIT_07s0104g01350 localization across Vitis species could provide insights into functional conservation and specialization:

• Generation of fluorescent protein fusions for various Vitis orthologs

• Transient expression in heterologous systems for standardized comparison

• Super-resolution microscopy to resolve fine membrane domain structures

• Fluorescence recovery after photobleaching (FRAP) to assess protein dynamics

Studies with CASP proteins have demonstrated that they can form stable membrane domains with low turnover . CASPs initially target the whole plasma membrane but are quickly removed from lateral plasma membranes and remain localized exclusively at the Casparian strip membrane domain . Similar dynamic studies with VIT_07s0104g01350 from different Vitis species would reveal conservation or divergence in membrane domain formation capabilities.

How can CRISPR-Cas9 genome editing be optimized for studying VIT_07s0104g01350 function in grapevine?

CRISPR-Cas9 technology offers powerful approaches for functional analysis, though application in woody perennials like grapevine presents specific challenges:

• Design considerations:

  • Target-specific sgRNAs with minimal off-target effects

  • Base editors for precise modification of conserved residues

  • Prime editing for introducing specific mutations or tags

• Delivery methods:

  • Agrobacterium-mediated transformation of embryogenic callus

  • Protoplast transformation followed by regeneration

  • Ribonucleoprotein (RNP) delivery to avoid transgene integration

• Screening strategies:

  • High-throughput amplicon sequencing for mutation detection

  • Protein-based screens using antibodies or fluorescent tags

  • Phenotypic screens based on predicted functions

• Validation approaches:

  • Complementation with wild-type or mutated versions

  • RNA-seq to identify downstream effects

  • Metabolomic analysis to detect changes in cell wall components

Researchers should adapt protocols that have been successful in other crop species, while accounting for the unique challenges of grapevine transformation efficiency and regeneration.

What approaches can resolve contradictory data regarding membrane domain formation by VIT_07s0104g01350?

When faced with contradictory experimental results regarding membrane domain formation, researchers should implement a multi-faceted approach:

• Methodological validation:

  • Compare protein expression levels across experiments

  • Standardize imaging parameters and quantification methods

  • Assess the impact of different tags on protein behavior

• Complementary techniques:

  • Combine fluorescence microscopy with electron microscopy

  • Use biochemical fractionation alongside imaging approaches

  • Implement orthogonal assays for membrane domain integrity

• Physiological relevance assessment:

  • Compare results from heterologous systems with native expression

  • Evaluate function under different environmental conditions

  • Assess age-dependent or developmental variations

• Systematic mutation analysis:

  • Create a panel of point mutations in conserved residues

  • Perform domain swaps between VIT_07s0104g01350 and known domain-forming proteins

  • Analyze the effects of post-translational modifications

How does sequence conservation of VIT_07s0104g01350 correlate with phenotypic differences among Vitis species?

Understanding the relationship between sequence variation and phenotypic differences requires:

• Comprehensive sequence analysis across Vitis species with diverse traits

• Correlation of sequence polymorphisms with disease resistance phenotypes

• Association studies linking specific amino acid variations to functional differences

• Evolutionary analysis to identify sites under positive selection

Studies comparing different Vitis species have revealed significant variation in traits such as antioxidant activity and disease resistance . For example, extracts from seeds of V. riparia showed higher antioxidant activity than those from V. amurensis, correlating with differences in phenolic composition . Similar comparative approaches could reveal whether sequence variations in VIT_07s0104g01350 contribute to such phenotypic differences.

What analytical techniques are most appropriate for characterizing post-translational modifications of VIT_07s0104g01350?

Post-translational modifications may significantly impact VIT_07s0104g01350 function. Researchers should consider:

• Mass spectrometry approaches:

  • Liquid chromatography-tandem mass spectrometry (LC-MS/MS)

  • Electron transfer dissociation (ETD) for preserving labile modifications

  • Targeted multiple reaction monitoring (MRM) for specific modifications

• Modification-specific techniques:

  • Phospho-specific antibodies

  • Glycoprotein staining methods

  • Ubiquitination detection systems

• Functional correlation methods:

  • Site-directed mutagenesis of modified residues

  • Inhibitors of specific modification enzymes

  • Temporal analysis during development or stress responses

The table below summarizes potential post-translational modifications and appropriate detection methods:

How might high-throughput phenotyping accelerate functional characterization of VIT_07s0104g01350?

Advanced phenotyping approaches can expedite functional characterization through:

• Automated imaging platforms for monitoring:

  • Growth and development parameters

  • Pathogen response phenotypes

  • Subcellular protein localization

• Multi-omics integration:

  • Correlation of transcriptome, proteome, and metabolome data

  • Network analysis to position VIT_07s0104g01350 in biological pathways

  • Identification of epistatic interactions through combinatorial genetics

• Field-based phenotyping:

  • Drone-based monitoring of agricultural traits

  • Wireless sensor networks for continuous physiological data

  • Machine learning for pattern recognition in complex datasets

These approaches would be particularly valuable for comparing transgenic lines with altered VIT_07s0104g01350 expression to wild-type plants under various environmental conditions.

What experimental design would best elucidate the evolutionary trajectory of VIT_07s0104g01350 function?

Understanding how VIT_07s0104g01350 function evolved requires a carefully designed evolutionary approach:

• Taxon sampling strategy:

  • Include representatives from major Vitaceae clades

  • Add outgroup species from related plant families

  • Sample species with varying environmental adaptations

• Functional conservation testing:

  • Complementation assays in model systems

  • Domain swapping between orthologs from diverse species

  • Ancestral sequence reconstruction and functional testing

• Correlation with evolutionary innovations:

  • Analysis of emergence of specialized cell types and tissues

  • Examination of adaptive traits across environmental gradients

  • Investigation of co-evolution with pathogens

Research has shown that a CASP-specific signature in the first extracellular loop (a nine-amino acid motif: ESLPFFTQF) is present in spermatophytes but absent in more ancient plant lineages like Physcomitrella patens and Selaginella moellendorffii . This suggests evolutionary specialization of certain CASP functions, and similar analyses could reveal the evolutionary trajectory of VIT_07s0104g01350.