GH3.11 Antibody

What is GH3.11 and what is its role in plant hormone signaling?

GH3.11/JAR1 belongs to the GH3 family of acyl acid amido synthetases that conjugate amino acids to plant hormones. Specifically, GH3.11 activates the defense hormone jasmonic acid (JA) by catalyzing the conjugation of isoleucine to JA, forming bioactive JA-Ile . This conjugation is essential for jasmonate perception and signaling in plants.

The GH3 family employs a two-step reaction mechanism that provides a potential proofreading mechanism to ensure fidelity of hormone modification . In the first step, GH3.11 catalyzes the adenylation of jasmonic acid using ATP to form a JA-AMP intermediate with the release of pyrophosphate. In the second step, the activated JA is transferred to the amino group of isoleucine, forming JA-Ile .

How does GH3.11 differ from other GH3 family proteins?

GH3 proteins in plants are divided into several groups based on their substrate preferences and functions:

• The largest subgroup modifies the growth-promoting hormone auxin (indole-3-acetic acid; IAA)

• The second largest class, which includes GH3.11, activates the defense hormone jasmonic acid

• Other GH3 proteins modify different acyl acids

While most GH3 proteins are substrate-specific, some show broader substrate ranges. For instance:

• GH3.11/JAR1 is specific for jasmonic acid

• GH3.2/YDK2 and GH3.17/VAS2 are specific for IAA

• GH3.5/WES1 contributes to both IAA and salicylic acid (SA) responses

This substrate specificity is important when designing experiments to study GH3.11 function or when generating specific antibodies.

What are the standard applications of GH3.11 antibodies in plant research?

GH3.11 antibodies can be used in several standard research applications:

• Western blotting: To detect and quantify GH3.11 protein levels in plant tissues under different conditions

• Immunofluorescence (IF): To visualize the subcellular localization of GH3.11

• Immunoprecipitation (IP): To purify GH3.11 and its interacting partners

• Enzyme-linked immunosorbent assay (ELISA): For quantitative detection of GH3.11 protein

Similar to antibodies against other GH3 proteins, GH3.11 antibodies typically function in various applications including ELISA, Western blotting, and immunofluorescence microscopy .

How can I validate the specificity of a GH3.11 antibody?

Validation of GH3.11 antibody specificity is crucial due to the high similarity between GH3 family proteins. Here's a comprehensive approach to validation:

• Positive and negative controls:

  • Use recombinant GH3.11 protein as a positive control

  • Use tissues from jar1-1 (GH3.11 mutant) plants as a negative control

  • Compare signal between wild-type and mutant samples

• Cross-reactivity testing:

  • Test against recombinant proteins of other GH3 family members, particularly those in the same phylogenetic group

  • Include closely related GH3 proteins like GH3.12/PBS3

• Peptide competition assay:

  • Pre-incubate the antibody with the immunizing peptide before application

  • Specific binding should be blocked by the peptide

• Western blot validation:

  • Confirm single band at the expected molecular weight (approximately 57-70 kDa)

  • Compare observed molecular weight with calculated weight (similar to GHDC at 57523 Da)

• Immunoprecipitation followed by mass spectrometry:

  • Confirm the identity of the immunoprecipitated protein

What are the optimal sample preparation methods for detecting GH3.11 in plant tissues?

Optimal sample preparation depends on the application, but generally follows these principles:

• Tissue collection and storage:

  • Harvest tissues at appropriate developmental stages or after treatments that induce JA signaling

  • Flash-freeze tissues in liquid nitrogen and store at -80°C

  • Avoid repeated freeze-thaw cycles

• Protein extraction:

  • Use buffer containing:

    • 50 mM Tris-HCl (pH 7.5)

    • 150 mM NaCl

    • 1 mM EDTA

    • 1% Triton X-100 or NP-40

    • Protease inhibitor cocktail

    • 1 mM DTT

  • Include phosphatase inhibitors if phosphorylation status is important

  • Keep samples cold during extraction

• Subcellular fractionation (if required):

  • Consider specific localization methods as GH3 domain-containing proteins can be primarily located in specific compartments (e.g., nuclear envelope)

• Fixation for immunofluorescence:

  • 4% paraformaldehyde in PBS for 20-30 minutes

  • Permeabilize with 0.1-0.5% Triton X-100

What controls should be included in experiments using GH3.11 antibodies?

For robust experimental design, include these controls:

• Positive controls:

  • Plants with induced JA signaling (e.g., wounded tissues, MeJA-treated)

  • Recombinant GH3.11 protein

• Negative controls:

  • jar1-1 mutant plants

  • Pre-immune serum or isotype control antibody

  • Secondary antibody only control

• Specificity controls:

  • Peptide competition assay

  • siRNA/CRISPR knockdown of GH3.11

• Loading/normalization controls:

  • Housekeeping proteins (e.g., actin, tubulin, GAPDH)

  • Total protein stain (e.g., Ponceau S)

How can GH3.11 antibodies be used to study enzyme-substrate interactions?

GH3.11 antibodies can be valuable tools for investigating enzyme-substrate interactions:

• Co-immunoprecipitation experiments:

  • Purify GH3.11 complexes using the antibody

  • Identify interacting partners by mass spectrometry

  • Follow protocols similar to those used for GST-AtWRI1 and His-TCP20 pull-down assays

• In vitro enzyme assays with immunopurified GH3.11:

  • Immunoprecipitate GH3.11 from plant extracts

  • Test activity with JA and isoleucine substrates

  • Analyze JA-Ile formation by LC-MS/MS

  • Compare with recombinant GH3.11 protein as reference

• Substrate competition assays:

  • Similar to assays performed with nalacin inhibitor

  • Determine Km values for different substrates

  • Test for mixed-type inhibition patterns

• Examining the two-step reaction mechanism:

  • Monitor pyrophosphate release in the first-half reaction

  • Study hydrolysis of acyl acid-AMP intermediates into acyl acid and AMP in the absence of amino acid substrates

  • Compare with other GH3 enzymes like AtGH3.2/YDK2, AtGH3.5/WES1, and AtGH3.17/VAS2

How can I use GH3.11 antibodies to investigate cross-talk between hormone signaling pathways?

Hormone cross-talk is a complex area where GH3.11 antibodies can provide valuable insights:

• Dual hormone treatments:

  • Treat plants with JA and other hormones (auxin, SA, ABA)

  • Monitor GH3.11 protein levels via immunoblotting

  • Compare with transcript analysis (qRT-PCR)

• Protein complex analysis:

  • Immunoprecipitate GH3.11 from plants treated with different hormones

  • Identify differential protein interactors through mass spectrometry

  • Look for components of other hormone signaling pathways

• Chromatin immunoprecipitation (ChIP) analysis:

  • If GH3.11 has nuclear functions, examine its association with chromatin

  • Target promoters of genes involved in multiple hormone pathways

  • Use protocols similar to those for transcription factors like TCP20 or WRI1

• Comparison with other GH3 proteins:

  • Compare GH3.11 with dual-function GH3s like GH3.5/WES1 that affect both auxin and SA responses

  • Investigate protein levels of multiple GH3 family members simultaneously

What techniques can be used to study post-translational modifications of GH3.11?

Post-translational modifications (PTMs) can regulate GH3.11 activity. Here are techniques to study them:

• Phosphorylation analysis:

  • Immunoprecipitate GH3.11 and analyze by:

    • Phospho-specific antibodies (if available)

    • Phos-tag SDS-PAGE to separate phosphorylated forms

    • Mass spectrometry to identify phosphorylation sites

• Protein stability and turnover:

  • Cycloheximide chase assays with immunoblotting

  • Study proteasome-dependent degradation using MG132

• Protein-protein interactions affecting activity:

  • Co-immunoprecipitation under different conditions

  • Yeast two-hybrid or split-luciferase assays to confirm interactions

  • In vitro binding assays similar to those used for WRI1-TCP20 interaction

• Subcellular localization changes:

  • Immunofluorescence microscopy under different conditions

  • Cell fractionation followed by immunoblotting

What are common issues with Western blot detection of GH3.11 and how can they be resolved?

How can I optimize immunoprecipitation protocols for GH3.11?

For successful immunoprecipitation of GH3.11:

• Buffer optimization:

  • Start with standard IP buffer (20 mM Tris-HCl pH 7.4, 150 mM NaCl, 1 mM DTT, 0.1 mM EDTA, 0.1% detergent)

  • Adjust salt concentration (150-300 mM) to balance specificity and yield

  • Test different detergents (IGEPAL CA-630, Triton X-100, NP-40)

• Antibody coupling:

  • Directly couple antibody to beads for cleaner results

  • Use protein A/G beads appropriate for the antibody species

• Pre-clearing samples:

  • Incubate lysate with beads alone before adding antibody

  • Reduces non-specific binding

• Washing optimization:

  • Start with 5 washes as performed in reference protocols

  • Balance between stringency (removing non-specific interactions) and maintaining specific interactions

• Elution methods:

  • Compare gentle (competition with peptide) vs. denaturing (SDS buffer) elution

  • Select based on downstream applications

What are the challenges in detecting low-abundance GH3.11 protein in plant tissues?

Low abundance of GH3.11 presents several challenges:

• Sensitivity limitations:

  • Use enhanced chemiluminescence (ECL) substrates for Western blots

  • Consider tyramide signal amplification for immunofluorescence

  • Develop sandwich ELISA with high-affinity antibody pairs

• Signal-to-noise ratio:

  • Increase antibody specificity through affinity purification

  • Optimize blocking and washing steps

  • Use monoclonal antibodies if possible

• Enrichment strategies:

  • Subcellular fractionation to concentrate the fraction containing GH3.11

  • Immunoprecipitation before Western blotting

  • Use tissues or conditions where GH3.11 is upregulated

• Alternative detection methods:

  • Consider protein mass spectrometry with targeted methods (SRM/MRM)

  • Proximity ligation assay (PLA) for enhanced sensitivity in tissue sections

How are GH3.11 antibodies being used to advance understanding of jasmonate signaling?

Current research applications of GH3.11 antibodies include:

• Investigating specificity mechanisms:

  • Studying the two-step reaction mechanism of GH3.11 that provides proofreading to ensure fidelity of hormone modification

  • Examining pyrophosphate release and intermediate hydrolysis patterns

• Protein-protein interaction networks:

  • Identifying novel interactors that regulate GH3.11 activity

  • Mapping the complete jasmonate signaling interactome

• Developmental regulation:

  • Analyzing tissue-specific and developmental stage-specific expression patterns

  • Correlating protein levels with JA-Ile accumulation and phenotypic responses

• Stress response dynamics:

  • Monitoring GH3.11 protein levels during biotic and abiotic stress responses

  • Comparing protein versus transcript dynamics during stress

What are emerging techniques for studying GH3.11 protein dynamics in living cells?

Emerging techniques applicable to GH3.11 research include:

• CRISPR-based tagging:

  • Endogenous tagging of GH3.11 with fluorescent proteins or epitope tags

  • Allows visualization or pulldown of native protein levels

• Single-molecule tracking:

  • Following individual GH3.11 molecules in living cells

  • Revealing dynamics not visible in population-based studies

• Optogenetic control:

  • Light-inducible expression or activity control of GH3.11

  • Permits precise temporal manipulation of signaling

• Proximity labeling:

  • BioID or APEX2 fusions to GH3.11

  • Identifies transient or weak interactors in native conditions

• High-throughput screening approaches:

  • Similar to chemical genetic screening used for nalacin identification as a GH3 inhibitor

  • Development of specific GH3.11 modulators