Recombinant Danio rerio E3 ubiquitin-protein ligase MARCH5 (41338)

What is MARCH5 and what are its key structural characteristics in zebrafish?

MARCH5 (also known as MARCHF5) is a membrane-associated RING finger protein that functions as an E3 ubiquitin ligase primarily localized to mitochondria. In zebrafish (Danio rerio), the full-length protein consists of 289 amino acids . The protein contains RING finger domains critical for its ubiquitin ligase activity, with the amino acid sequence: MACVDEPPEKHCWVCFATEKEDRAAEWVSPCRCKGCTKWIHQSCLQRWLDEKQKGNSGGAVSCPQCGTEYRIVFPKMGPVVYFLQQVDRALSRASPFAAAGVVVGTVYWSAVTYGAVTVMQVVGHKKGLDVMERADPLFLLMGLPTIPVMLVLGKMIRWEDYVVRLWQRHSAKLQIFSGLVPGMGRALPRVPVEGSYGGDHLSVSRTLCGALIFPSIANLVGRLLFRRVTSNLQRTILGGIAFVVMKGVLKVYFKQQQYLIQANRHILNYPEPEGQADGATEDEDSSNE .

The protein shares conserved functional domains with mammalian MARCH5 proteins, including the characteristic RING-CH domain essential for its E3 ligase activity.

How does recombinant Danio rerio MARCH5 protein need to be stored and reconstituted for experimental use?

For optimal stability and activity, recombinant Danio rerio MARCH5 protein should be:

• Initially stored at -20°C/-80°C upon receipt

• Reconstituted in deionized sterile water to a concentration of 0.1-1.0 mg/mL

• Supplemented with 5-50% glycerol (recommended final concentration: 50%)

• Aliquoted to avoid repeated freeze-thaw cycles

• Working aliquots can be stored at 4°C for up to one week

The reconstituted protein is typically supplied in Tris/PBS-based buffer containing 6% Trehalose at pH 8.0 . Brief centrifugation prior to opening is recommended to bring contents to the bottom of the vial.

What are the primary biological functions of MARCH5 in cellular processes?

MARCH5 serves critical roles in:

• Mitochondrial dynamics regulation: MARCH5 binds to key proteins involved in mitochondrial fission and fusion, including mitochondrial fission 1 protein (hFis1), dynamin-related protein 1 (Drp1), and mitofusin 2 (Mfn2) .

• Ubiquitination of substrate proteins: As an E3 ubiquitin ligase, MARCH5 targets specific proteins for ubiquitination, with Mfn1 identified as a major ubiquitylation substrate in mammalian cells .

• Peroxisome biogenesis: MARCH5 is essential for the formation of vesicles in the de novo biogenesis of peroxisomes from mitochondria, controlling the budding of PEX3-containing vesicles from mitochondria .

• Cellular senescence regulation: Loss of MARCH5 function can promote cellular senescence through mechanisms involving mitochondrial elongation .

What expression systems are optimal for producing recombinant Danio rerio MARCH5, and what purification strategies yield the highest quality protein?

Based on available data, recombinant Danio rerio MARCH5 can be effectively produced in:

Expression System: E. coli appears to be suitable for expressing the full-length protein (1-289aa) with an N-terminal His tag .

Purification Strategy:

• Affinity chromatography using the N-terminal His tag as the primary purification step

• Additional purification steps may be required to achieve >90% purity as determined by SDS-PAGE

• Buffer exchange to Tris/PBS-based buffer with 6% Trehalose, pH 8.0, for final formulation

The choice of expression system may depend on experimental needs. While E. coli is effective for basic structural studies, mammalian or insect cell expression systems might be preferred for functional studies requiring post-translational modifications.

What are the most effective methods for studying MARCH5 interactions with its substrate proteins in zebrafish models?

To investigate MARCH5 interactions with substrate proteins in zebrafish:

In Vitro Approaches:

• Co-immunoprecipitation using tagged recombinant proteins

• Pull-down assays with purified recombinant MARCH5 and potential substrates

• Surface plasmon resonance (SPR) or biolayer interferometry for binding kinetics

In Vivo/Cellular Approaches:

• CRISPR/Cas9-mediated knockout or knockdown of MARCH5 in zebrafish cells or embryos

• Fluorescence resonance energy transfer (FRET) assays to detect protein-protein interactions

• Proximity ligation assays to visualize interactions in situ

For studying mitochondrial dynamics specifically, monitoring changes in mitochondrial morphology following MARCH5 manipulation is essential, as MARCH5 knockdown has been shown to promote accumulation of highly interconnected and elongated mitochondria .

How can researchers effectively design experiments to investigate MARCH5's role in peroxisome biogenesis in zebrafish models?

To study MARCH5's role in peroxisome biogenesis:

Experimental Design Strategy:

• Generate MARCH5-deficient zebrafish cell lines or organisms using CRISPR/Cas9 technology

• Utilize fluorescent peroxisomal markers (e.g., GFP-PEX3) to visualize peroxisome formation

• Employ time-lapse microscopy to track mitochondria-derived vesicle (MDV) formation and PEX3-containing vesicle budding

Key Measurements:

• Quantification of PEX3-containing vesicle budding events from mitochondria

• Assessment of pre-peroxisome formation rates

• Measurement of mature peroxisome numbers and morphology

• Analysis of peroxisomal protein import efficiency

Since MARCH5 has been shown to be essential for the budding of PEX3-containing vesicles from mitochondria in human cells , similar functions might be conserved in zebrafish. Comparing wildtype to MARCH5-deficient zebrafish could reveal conserved mechanisms in peroxisome biogenesis.

How does zebrafish MARCH5 compare functionally with its mammalian orthologs, and what unique experimental advantages does the zebrafish model offer?

Comparative Analysis of MARCH5 Orthologs:

Experimental Advantages of Zebrafish Models:

• Optical transparency of embryos allows real-time visualization of organelles and protein interactions

• Rapid development and high fecundity enable large-scale genetic and drug screening

• Easier genetic manipulation compared to mammals

• Conservation of core metabolic pathways while allowing for model-specific adaptations

• Ability to perform both in vitro and in vivo studies in the same model organism

Zebrafish models could be particularly valuable for investigating the evolutionary conservation of MARCH5 functions across vertebrates, especially in processes like mitochondrial dynamics and peroxisome biogenesis.

What are the molecular mechanisms by which MARCH5 deficiency leads to cellular senescence, and how can this be investigated using recombinant zebrafish MARCH5?

MARCH5 deficiency leads to cellular senescence through the following proposed mechanisms:

• Mitochondrial network remodeling: MARCH5 knockdown causes accumulation of highly interconnected and elongated mitochondria .

• Mfn1 accumulation: MARCH5-depleted cells show significant increases in Mfn1 levels, identifying it as a major ubiquitylation substrate .

• Drp1 activity inhibition: Loss of MARCH5 may block Drp1 activity, contributing to abnormal mitochondrial morphology .

Experimental Approach to Investigate This Using Recombinant Zebrafish MARCH5:

• Reconstitution experiments: Express wildtype or mutant recombinant zebrafish MARCH5 in MARCH5-depleted cells to identify critical domains

• Substrate identification: Perform in vitro ubiquitination assays with recombinant MARCH5 and potential substrates (Mfn1, Drp1)

• Domain mutation studies: Create point mutations in the RING domain of recombinant MARCH5 to assess functional importance

• Comparative senescence assays: Measure senescence-associated beta-galactosidase (SA-beta-Gal) activity in:

  • Control cells

  • MARCH5-depleted cells

  • MARCH5-depleted cells reconstituted with recombinant wildtype MARCH5

  • MARCH5-depleted cells reconstituted with recombinant mutant MARCH5

Evidence suggests that the introduction of GTPase-deficient Mfn1(T109A) into MARCH5-RNAi cells disrupts mitochondrial elongation and abolishes increased SA-beta-Gal activity, while ectopic expression of Drp1 reverses the aberrant mitochondrial phenotypes in MARCH5-RNAi cells . These findings provide a foundation for investigating whether similar mechanisms operate in zebrafish.

How can researchers use recombinant Danio rerio MARCH5 to study the evolutionary conservation of mitochondria-derived vesicle (MDV) formation in peroxisome biogenesis?

Research Strategy:

• Comparative biochemical analysis:

  • Perform in vitro vesicle budding assays using purified mitochondria and recombinant MARCH5 from different species

  • Compare ubiquitination substrates between zebrafish and mammalian MARCH5

  • Assess interchangeability of MARCH5 proteins across species in rescue experiments

• Structure-function conservation:

  • Generate chimeric MARCH5 proteins combining domains from zebrafish and mammalian orthologs

  • Identify critical residues required for MDV formation through targeted mutagenesis

  • Map the evolutionary conservation of functional domains across vertebrates

• Imaging-based approaches:

  • Use super-resolution microscopy to visualize MDV formation in real-time

  • Track PEX3-containing vesicles using fluorescently tagged proteins

  • Quantify budding events in the presence of wildtype or mutant MARCH5

The discovery that MARCH5 is essential for the formation of vesicles in the de novo biogenesis of peroxisomes from mitochondria opens research opportunities to investigate whether this role is conserved in zebrafish. The dual organelle localization of MARCH5 (mitochondria and peroxisomes) suggests it may serve as a key regulator of organelle crosstalk across vertebrate species.

What are the main challenges in expressing and purifying functional recombinant Danio rerio MARCH5, and how can these be addressed?

Key Challenges and Solutions:

For highest quality recombinant protein, consider:

• Using Lemo21(DE3) E. coli strain for tightly controlled expression

• Employing immobilized metal affinity chromatography followed by size exclusion chromatography

• Validating protein activity through in vitro ubiquitination assays

How can researchers effectively study the functional relationship between MARCH5 and peroxisome biogenesis in zebrafish systems?

To effectively study MARCH5's role in peroxisome biogenesis in zebrafish:

Integrated Research Approach:

• Genetic manipulation strategies:

  • Generate zebrafish MARCH5 knockouts using CRISPR/Cas9

  • Create conditional knockouts for temporal control of MARCH5 expression

  • Develop transgenic lines expressing fluorescently tagged MARCH5 and peroxisomal markers

• Biochemical assessments:

  • Isolate mitochondria from wild-type and MARCH5-deficient zebrafish

  • Perform in vitro budding assays to measure MDV formation

  • Analyze ubiquitination of potential substrate proteins like PEX3

• Advanced imaging techniques:

  • Employ live confocal microscopy of zebrafish embryos to track peroxisome formation

  • Use correlative light and electron microscopy to visualize MDV ultrastructure

  • Implement super-resolution microscopy to detect protein interactions at mitochondria-peroxisome contact sites

• Functional verification:

  • Rescue MARCH5 deficiency phenotypes with recombinant wild-type protein

  • Test the ability of mutant MARCH5 variants to restore peroxisome biogenesis

  • Assess peroxisomal metabolic functions in MARCH5-deficient zebrafish

Since MARCH5 has been shown to specifically impede the budding of PEX3-containing vesicles from mitochondria in human cells , researchers should focus on whether similar specificity exists in zebrafish, potentially revealing evolutionarily conserved mechanisms of organelle biogenesis.

What technical considerations are important when designing experiments to study the impact of MARCH5 on mitochondrial dynamics and cellular senescence in zebrafish models?

Critical Technical Considerations:

• Zebrafish-specific adaptations:

  • Optimize antibodies for zebrafish MARCH5 detection

  • Adjust cellular senescence assays for zebrafish cells (temperature, pH optimization)

  • Consider zebrafish-specific mitochondrial dynamics

• Senescence assessment methods:

  • Standardize SA-beta-Gal activity assays for zebrafish cells

  • Include multiple senescence markers (p21, p53, SASP factors)

  • Develop zebrafish-specific senescence reporter lines

• Mitochondrial dynamics visualization:

  • Use mitochondria-targeted fluorescent proteins adaptable to zebrafish systems

  • Optimize live-imaging conditions for zebrafish cells

  • Quantify parameters including mitochondrial length, interconnectivity, and membrane potential

• Experimental controls:

  • Include Mfn1(T109A) expression to disrupt mitochondrial elongation

  • Test ectopic Drp1 expression to potentially reverse phenotypes

  • Compare effects across multiple zebrafish cell types

Research indicates that MARCH5 knockdown promotes cellular enlargement and flattening accompanied by increased senescence-associated beta-galactosidase activity, indicating cellular senescence . This phenotype is linked to mitochondrial elongation that can be reversed by ectopic expression of Drp1 . Experimental designs should verify whether these mechanisms are conserved in zebrafish systems.

What are the promising research avenues for investigating the role of MARCH5 in non-canonical pathways beyond mitochondrial dynamics and peroxisome biogenesis?

Emerging research suggests MARCH5 may have broader cellular functions beyond its established roles:

• Cell cycle regulation: Investigate potential interactions between MARCH5 and cell cycle regulators, given the connection to cellular senescence .

• Stress response pathways: Explore MARCH5's potential role in cellular stress responses, possibly through selective mitophagy or organelle quality control.

• Metabolic regulation: Examine how MARCH5-mediated changes in mitochondrial and peroxisomal function affect cellular metabolism in zebrafish.

• Developmental processes: Study MARCH5 expression patterns during zebrafish development to identify stage-specific functions.

• Neurological functions: Investigate MARCH5's role in neuronal health, as mitochondrial dynamics are critical for neuronal function.

Experimental strategies should include temporal and tissue-specific MARCH5 knockout models, differential proteomics to identify novel interacting partners, and metabolomic analyses to capture downstream effects of MARCH5 deficiency.

How might comparative studies between zebrafish and mammalian MARCH5 inform therapeutic strategies for mitochondrial dynamics-related diseases?

Translational Research Potential:

Zebrafish MARCH5 studies could inform therapeutic strategies for:

• Neurodegenerative diseases with mitochondrial dysfunction

• Age-related conditions involving cellular senescence

• Peroxisomal disorders with compromised biogenesis

• Metabolic diseases affecting mitochondrial-peroxisomal crosstalk

The finding that MARCH5 deficiency promotes cellular senescence through mitochondrial elongation suggests potential therapeutic avenues for age-related diseases, while its role in peroxisome biogenesis offers insights for peroxisomal disorders.

What are the most reliable protocols and resources for researchers working with recombinant Danio rerio MARCH5?

Recommended Protocols:

• Reconstitution and Storage:

  • Reconstitute lyophilized protein 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 for long-term storage

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

• Protein Handling:

  • Centrifuge vials briefly before opening

  • Use Tris/PBS-based buffer with 6% Trehalose, pH 8.0, for working solutions

  • Avoid repeated freeze-thaw cycles

• Activity Verification:

  • In vitro ubiquitination assays using recombinant substrates

  • Mitochondrial dynamics assays in cell culture systems

Essential Resources:

• UniProt ID: Q6NYK8 for sequence information and functional annotations

• Zebrafish model resources at ZFIN (zebrafish.org)

• Peroxisome and mitochondria visualization protocols

What quality control measures should be implemented when working with recombinant Danio rerio MARCH5 to ensure experimental reproducibility?

Critical Quality Control Measures:

• Protein Integrity Verification:

  • SDS-PAGE to confirm >90% purity

  • Western blot with anti-His tag and anti-MARCH5 antibodies

  • Mass spectrometry to verify protein identity and detect modifications

• Functional Activity Assessment:

  • In vitro ubiquitination assays with known substrates

  • Binding assays with interaction partners (Mfn1, Drp1, hFis1)

  • Circular dichroism to confirm proper protein folding

• Storage and Stability Monitoring:

  • Aliquot protein to prevent repeated freeze-thaw cycles

  • Test activity retention over time under different storage conditions

  • Document lot-to-lot variation in activity

• Experimental Validation:

  • Include positive and negative controls in all experiments

  • Perform cellular complementation assays with MARCH5-deficient cells

  • Validate findings across multiple experimental systems