Recombinant Arabidopsis thaliana Uncharacterized membrane protein At4g09580 (At4g09580)

How can I obtain recombinant At4g09580 protein for my research?

There are two primary approaches to obtaining the protein:

• Purchase commercially available recombinant protein: Full-length recombinant At4g09580 protein with an N-terminal His-tag is commercially available (e.g., catalog number RFL32711AF). This protein is expressed in E. coli and supplied as a lyophilized powder with >90% purity as determined by SDS-PAGE .

• Express it yourself using available plasmids: The Arabidopsis Biological Resource Center (ABRC) offers plasmid stock DKLAT4G09580, which is an ORF expression clone in LIC6 vector. This resource is available for $15 (base price) or $120 (commercial price) and is shipped as a bacterial stab of E. coli DH10B containing the plasmid. The plasmid carries a spectinomycin resistance marker for selection .

For self-expression, follow standard protocols for bacterial transformation, culture, and protein purification using affinity chromatography based on the His-tag.

What are the optimal storage conditions for recombinant At4g09580 protein?

For long-term storage of recombinant At4g09580 protein, follow these evidence-based recommendations:

• Initial storage: Store the lyophilized powder at -20°C to -80°C upon receipt.

• Reconstitution: Before opening, briefly centrifuge the vial to bring contents to the bottom. Reconstitute the protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL.

• Working aliquots: For storage of working aliquots, keep at 4°C for up to one week.

• Long-term storage: Add glycerol to a final concentration of 5-50% (50% is recommended) and store in aliquots at -20°C to -80°C.

• Avoid degradation: Repeated freeze-thaw cycles are not recommended as they may lead to protein degradation .

The standard storage buffer is Tris/PBS-based with 6% trehalose at pH 8.0, which helps maintain protein stability during storage and reconstitution.

How do I design an experiment to study At4g09580 in Arabidopsis thaliana?

When designing experiments to study At4g09580 in Arabidopsis thaliana, consider this methodological framework:

• Experimental planning:

  • Define clear objectives (phenotypic characterization, protein localization, expression analysis, etc.)

  • Determine experimental conditions (growth conditions, treatments)

  • Choose appropriate controls (wild-type plants, known mutants)

  • Decide on duration and sampling timepoints

  • Calculate required sample sizes and biological replicates (8 replicates per condition is common)

• Growth chamber setup:

  • Use randomized block designs to minimize position effects in growth chambers

  • Document environmental conditions precisely (temperature: typically 20.5°C, humidity: ~70%, photoperiod, PAR [typically max: 200 μmol])

  • Consider using automated systems like PHENOPSIS for highly controlled conditions

• Data collection planning:

  • Create a joint display table that integrates quantitative and qualitative data collection

  • Align related quantitative and qualitative variables by constructing a data sources table with side-by-side columns

  • Link constructs to variables across different data sources

What expression systems are suitable for producing recombinant At4g09580?

Based on the available research data, several expression systems have been successfully used for At4g09580 production:

For E. coli expression:

• The protein has been successfully expressed in E. coli using His-tag fusion

• Growth in LB media at 37°C overnight is recommended

• Spectinomycin is used as a selection marker

For protein purification following expression:

• Harvest cells and lyse using appropriate buffer systems

• Perform affinity chromatography using the His-tag

• Verify purity using SDS-PAGE (aim for >90% purity)

• Consider buffer exchange to remove imidazole after purification

How can I assess the subcellular localization of At4g09580?

To determine the subcellular localization of At4g09580, consider these methodological approaches:

• Fluorescent protein fusion:

  • Clone At4g09580 into vectors containing fluorescent protein tags (GFP, YFP, etc.)

  • Use Gateway cloning for efficient construct generation

  • Transform Arabidopsis using the floral dip method or use transient expression in Nicotiana benthamiana

  • Visualize using confocal microscopy

• Immunolocalization:

  • Generate specific antibodies against At4g09580 or use antibodies against the His-tag in recombinant versions

  • Fix and permeabilize plant tissues

  • Perform immunostaining and analyze using confocal microscopy

• Subcellular fractionation:

  • Separate cellular components through differential centrifugation

  • Analyze protein content of different fractions using Western blotting

  • Use known markers for different cellular compartments as controls

• Co-localization studies:

  • Express At4g09580 fusions alongside known membrane compartment markers

  • Calculate co-localization coefficients using imaging software

  • Consider using FRET or BiFC to study protein-protein interactions at specific membranes

When interpreting results, remember that membrane proteins can be challenging to localize precisely due to trafficking between compartments during synthesis and degradation.

What are the best methods for analyzing At4g09580 expression patterns?

To accurately analyze At4g09580 expression patterns, employ these complementary approaches:

• Transcriptomic analysis:

  • Use RNA-Seq to quantify At4g09580 mRNA levels across different tissues, developmental stages, or treatments

  • Follow established protocols for RNA extraction, library preparation, and sequencing

  • Employ appropriate statistical analysis for differential expression

  • Consider working with specialized facilities (e.g., QBiC, Tübingen) for high-quality data generation

• RT-PCR and qRT-PCR:

  • Design specific primers for At4g09580

  • Extract total RNA from tissues of interest

  • Perform reverse transcription using standard protocols

  • For qRT-PCR, use reference genes appropriate for the experimental conditions

  • Calculate relative expression using the 2^-ΔΔCt method

• Promoter-reporter fusions:

  • Clone the At4g09580 promoter region (typically 1-2kb upstream of the start codon)

  • Fuse to reporter genes (GUS, LUC, fluorescent proteins)

  • Generate stable transgenic lines using floral dip transformation

  • Analyze reporter expression in different tissues and conditions

• Western blotting:

  • Extract proteins from tissues of interest

  • Separate proteins using SDS-PAGE

  • Transfer to membrane using wet transfer methods

  • Probe with antibodies specific to At4g09580 or its tags

  • Visualize using appropriate detection systems

How do I interpret phosphoproteomic data related to At4g09580?

Interpreting phosphoproteomic data for At4g09580 requires systematic analysis:

• Sample preparation considerations:

  • Ensure proper extraction of membrane proteins (often challenging)

  • Use appropriate phosphopeptide enrichment techniques (TiO2, IMAC, etc.)

  • Consider sample multiplexing using isotopic labeling (e.g., TMT, iTRAQ)

• Data analysis workflow:

  • Identify phosphorylation sites using mass spectrometry

  • Determine site localization probability scores

  • Quantify changes in phosphorylation levels

  • Perform statistical analysis to identify significant changes

• Functional interpretation:

  • Map phosphorylation sites to protein domains

  • Assess conservation of phosphorylation sites across species

  • Predict kinases responsible using tools like NetPhos, GPS, or PHOSIDA

  • Integrate with protein-protein interaction data and signaling pathways

• Validation strategies:

  • Generate phospho-specific antibodies

  • Create phosphomimetic (S/T to D/E) and phospho-null (S/T to A) mutants

  • Perform functional assays to determine the impact of phosphorylation

  • Consider in vitro kinase assays to confirm direct phosphorylation

How can I determine the redox sensitivity of At4g09580?

Although specific redox studies of At4g09580 are not documented in the provided search results, we can adapt methodologies from related proteins like AHK5:

• In vitro redox midpoint potential determination:

  • Express and purify recombinant At4g09580

  • Prepare glutathione buffers with varying GSH/GSSG ratios to establish a range of defined redox potentials

  • Incubate protein with these buffers

  • Analyze redox state using techniques like AMS labeling or redox proteomics

  • Calculate the redox midpoint potential using the Nernst equation

  • For comparison, the in vitro GSH/GSSG Redox Midpoint Potential of recombinant AHK5_ID is approximately -154 mV

• Identification of redox-sensitive residues:

  • Perform site-directed mutagenesis of cysteine residues

  • Assess the impact on redox sensitivity

  • Use mass spectrometry to identify specific modifications (disulfide bridges, glutathionylation, etc.)

  • Consider structural modeling to identify potentially exposed cysteines

• In vivo redox studies:

  • Generate transgenic plants expressing At4g09580 with redox-sensitive tags

  • Apply oxidative stress treatments (H2O2, paraquat, etc.)

  • Monitor protein modifications and functional changes

  • Consider roGFP fusion constructs for real-time redox monitoring

What approaches can I use to identify potential interaction partners of At4g09580?

To identify protein-protein interactions for At4g09580, consider these complementary approaches:

• Co-immunoprecipitation (Co-IP):

  • Express tagged versions of At4g09580 in plants

  • Prepare protein extracts under non-denaturing conditions

  • Perform immunoprecipitation using tag-specific antibodies

  • Identify co-precipitated proteins using mass spectrometry

  • Standard protocol:
    a) Harvest and grind plant tissue in liquid nitrogen
    b) Extract proteins in appropriate buffer
    c) Pre-clear lysate with protein A/G beads
    d) Incubate with antibody-conjugated beads
    e) Wash thoroughly to remove non-specific binding
    f) Elute and analyze by mass spectrometry

• Yeast two-hybrid screening:

  • Clone At4g09580 domains (avoiding transmembrane regions) as bait

  • Screen against Arabidopsis cDNA libraries

  • Validate positive interactions with directed Y2H and other methods

  • Consider membrane-based Y2H systems for full-length protein

• Split-ubiquitin membrane yeast two-hybrid:

  • Particularly useful for membrane proteins like At4g09580

  • Clone full-length At4g09580 as bait

  • Screen against membrane protein libraries

  • Validate potential interactions using other methods

• Proximity labeling approaches:

  • Fuse At4g09580 with BioID or TurboID

  • Express in Arabidopsis

  • Provide biotin for proximity-dependent labeling

  • Purify biotinylated proteins and identify by mass spectrometry

How can I integrate transcriptomic and phosphoproteomic data to understand At4g09580 function?

Integrating multi-omics data requires sophisticated analytical approaches:

• Data collection and preprocessing:

  • Ensure comparable experimental conditions for both datasets

  • Apply appropriate normalization methods

  • Filter data for quality and significance

  • Consider using joint display methodology to align related data points

• Correlation analysis:

  • Identify correlations between transcript levels and phosphorylation events

  • Determine whether phosphorylation changes precede or follow transcriptional changes

  • Create correlation networks to visualize relationships

• Pathway enrichment analysis:

  • Perform Gene Ontology (GO) and KEGG pathway enrichment for both datasets

  • Identify commonly enriched pathways

  • Look for complementary pathways that might be differentially regulated

• Network analysis:

  • Construct protein-protein interaction networks

  • Overlay transcriptomic and phosphoproteomic data

  • Identify network modules showing coordinated regulation

  • Use tools like Cytoscape for visualization and analysis

• Integration framework:

  • Consider constructing a joint display table with 6 columns that delineates:
    a) Separate data sources
    b) Links between constructs and quantitative variables
    c) Links between constructs and qualitative variables
    d) Integration across data sources

What are the best approaches for functional characterization of At4g09580 using CRISPR-Cas9 gene editing?

For comprehensive functional characterization using CRISPR-Cas9:

• Design strategy:

  • Design multiple guide RNAs targeting different regions of At4g09580

  • Consider guides targeting 5' regions for complete knockouts

  • Design guides for specific domains for partial functionality studies

  • Use tools like CRISPR-P or CRISPOR for guide RNA design and off-target prediction

• Vector construction and plant transformation:

  • Clone guide RNAs into appropriate CRISPR-Cas9 vectors

  • Consider using egg cell-specific promoters for increased efficiency

  • Transform Arabidopsis using floral dip method

  • Select transformants using appropriate markers

• Mutant screening and validation:

  • Screen T1 plants using PCR and sequencing

  • Identify homozygous mutations in T2 generation

  • Confirm protein absence using Western blotting

  • Verify lack of off-target mutations through whole-genome sequencing

• Phenotypic analysis:

  • Characterize growth and development under standard conditions

  • Test multiple environmental conditions and stresses

  • Consider using automated phenotyping platforms like PHENOPSIS

  • Protocol example from PHENOPSIS:
    a) Prepare substrate with measured initial water content
    b) Sow seeds and germinate under controlled conditions
    c) Program automated watering and image acquisition
    d) Collect data on growth-related traits using semi-automated procedures

• Complementation studies:

  • Reintroduce wild-type or modified At4g09580 into knockout lines

  • Assess restoration of phenotypes

  • Use domain swaps or point mutations to investigate specific protein functions

How can I optimize protein extraction and purification for membrane proteins like At4g09580?

Membrane proteins present unique challenges for extraction and purification. Here's a detailed protocol:

• Tissue preparation and cell lysis:

  • Harvest tissues and flash-freeze in liquid nitrogen

  • Grind thoroughly to fine powder

  • Use detergent-containing buffers (e.g., 1% Triton X-100, 0.5% CHAPS, or 1% DDM)

  • Include protease inhibitors and phosphatase inhibitors if studying phosphorylation

  • Consider using French press or sonication for bacterial cells

• Membrane fraction isolation:

  • Perform differential centrifugation:
    a) Low-speed centrifugation (1,000-5,000 × g) to remove unbroken cells and debris
    b) High-speed centrifugation (100,000 × g) to collect membrane fractions

  • Wash membrane pellet with carbonate buffer (pH 11) to remove peripheral proteins

• Solubilization optimization:

  • Test multiple detergents (DDM, CHAPS, OG, digitonin)

  • Optimize detergent concentration, temperature, and incubation time

  • Use gentle agitation to avoid protein denaturation

• Affinity purification:

  • For His-tagged At4g09580:
    a) Use Ni-NTA or TALON resin
    b) Include low concentrations of detergent in all buffers
    c) Use imidazole gradient for elution
    d) Consider on-column detergent exchange if needed

• Quality assessment:

  • Verify purity by SDS-PAGE (aim for >90% purity)

  • Confirm identity by Western blotting

  • Assess protein activity/folding using appropriate functional assays

What experimental approaches can I use to study the membrane topology of At4g09580?

Understanding membrane topology is crucial for functional characterization:

• In silico prediction:

  • Use multiple topology prediction tools (TMHMM, Phobius, TOPCONS)

  • Create consensus predictions

  • Identify potential transmembrane segments, cytoplasmic, and extracellular domains

• Protease protection assays:

  • Isolate membrane fractions containing At4g09580

  • Treat with proteases (e.g., trypsin, proteinase K) with or without membrane permeabilization

  • Analyze protected fragments by immunoblotting

  • Protected regions are likely inside vesicles (corresponding to cytoplasmic domains in cells)

• Reporter fusion approach:

  • Create fusions with reporters at different positions

  • For N- and C-termini, use fluorescent proteins or epitope tags

  • For internal sites, use enzyme reporters like alkaline phosphatase (active in periplasm) or beta-galactosidase (active in cytoplasm)

  • Express in appropriate systems and determine reporter activity/localization

• Cysteine scanning mutagenesis:

  • Replace residues one by one with cysteine

  • Treat with membrane-permeable and impermeable sulfhydryl reagents

  • Analyze accessibility patterns to determine topology

  • Can be combined with mass spectrometry for high-throughput analysis

How can I develop a high-throughput phenotypic screen to identify the function of At4g09580?

Developing a comprehensive phenotypic screen requires careful planning and execution:

• Screen design considerations:

  • Use knockout/knockdown lines of At4g09580

  • Consider overexpression lines for gain-of-function analysis

  • Include appropriate wild-type controls

  • Design completely randomized block experiments to minimize position effects

• Automated phenotyping approach:

  • Utilize systems like PHENOPSIS for controlled environment and automated data collection

  • Program environmental conditions (temperature, humidity, photoperiod)

  • Set up automated watering and image acquisition

  • Collect multiple data types (visible, infrared, fluorescence images)

• Growth and developmental parameters:

  • Measure germination rates and timing

  • Track rosette development and leaf emergence

  • Quantify growth rates using image analysis

  • Measure flowering time and reproductive development

• Stress response assays:

  • Test responses to abiotic stresses:
    a) Water deficit (controlled by soil water content)
    b) Temperature extremes
    c) Salt stress
    d) Oxidative stress (H2O2, paraquat)

  • Monitor physiological parameters:
    a) Chlorophyll fluorescence
    b) Stomatal conductance
    c) Water use efficiency
    d) Biomass accumulation

• Data analysis pipeline:

  • Develop semi-automated image analysis workflows

  • Apply statistical methods for growth curve analysis

  • Use principal component analysis to identify key phenotypic variables

  • Consider machine learning approaches for pattern recognition

How do I reconcile contradictory data about At4g09580 function from different experimental approaches?

When faced with contradictory results, follow this systematic approach:

• Critical evaluation of methodologies:

  • Compare experimental conditions and protocols in detail

  • Assess the sensitivity and specificity of each method

  • Consider technical limitations and potential artifacts

  • Evaluate statistical approaches and significance thresholds

• Integration of multiple data types:

  • Create joint display tables to align related data points

  • Identify where results converge and diverge

  • Look for conditional effects (tissue-specific, developmental stage-dependent, etc.)

  • Consider constructing a methodological process with multiple iterations to develop refined joint displays

• Validation experiments:

  • Design experiments specifically targeting contradictory findings

  • Use orthogonal methods to address the same question

  • Increase biological and technical replicates

  • Consider blinded experimental design to reduce bias

• Collaborative approach:

  • Engage with experts in different methodologies

  • Consider multi-lab validation studies

  • Share raw data and analysis pipelines for independent verification

  • Develop consensus protocols for studying At4g09580

• Contextual interpretation:

  • Consider that seemingly contradictory results may reflect biological complexity

  • Explore whether results differ due to:
    a) Tissue-specific effects
    b) Developmental timing
    c) Environmental conditions
    d) Genetic background differences

  • Develop integrated models that accommodate conditional functionality

What emerging technologies could advance our understanding of At4g09580 function?

Several cutting-edge approaches could provide new insights:

• Cryo-EM structural analysis:

  • Express and purify sufficient quantities of At4g09580

  • Optimize detergent/nanodisc/amphipol conditions

  • Perform single-particle cryo-EM

  • Resolve 3D structure to understand functional domains and potential interaction sites

• AlphaFold2/RoseTTAFold predictions:

  • Generate AI-based structural predictions

  • Validate key structural features experimentally

  • Use predicted structures to guide functional studies and mutation design

• Single-cell transcriptomics:

  • Apply to Arabidopsis tissues to identify cell-specific expression patterns

  • Correlate At4g09580 expression with cell types and developmental stages

  • Identify co-expressed genes for functional hypothesis generation

• Spatial transcriptomics/proteomics:

  • Map At4g09580 expression with spatial resolution

  • Correlate with tissue structures and developmental gradients

  • Identify localized functional contexts

• Optogenetic control:

  • Engineer light-responsive domains into At4g09580

  • Enable temporal and spatial control of protein function

  • Study acute effects of protein activation/inactivation

How can I develop an integrative research program to fully characterize At4g09580?

A comprehensive research program should integrate multiple approaches:

• Sequential research phases:

  Phase	Focus	Key Methods	Expected Outcomes
  1	Basic characterization	Subcellular localization, Expression analysis, Knockout phenotyping	Fundamental understanding of protein context
  2	Molecular function	Protein-protein interactions, Structure-function analysis, Domain mapping	Mechanistic insights into protein activity
  3	Physiological role	Stress responses, Developmental analysis, Metabolic profiling	Understanding of biological significance
  4	Systems integration	Multi-omics integration, Network analysis, Mathematical modeling	Contextual understanding within cellular systems

• Iterative experimental design:

  • Use findings from each phase to inform subsequent experiments

  • Develop joint display tables to integrate data across methods

  • Regularly reassess research priorities based on emerging findings

• Collaborative framework:

  • Engage specialists in different methodologies

  • Establish consistent protocols across research groups

  • Implement data sharing and integration strategies

  • Consider developing a research consortium for comprehensive characterization

• Technology development:

  • Invest in method optimization for membrane protein analysis

  • Develop new tools for functional analysis in planta

  • Create computational pipelines for integrated data analysis

  • Consider developing At4g09580-specific resources (antibodies, reporter lines, etc.)