Recombinant UPF0041 protein R07E5.13 (R07E5.13)

What expression systems are commonly used for recombinant R07E5.13 production?

E. coli is the standard expression system for recombinant R07E5.13, typically using an N-terminal His-tag for purification purposes . This approach mirrors common practices for heterologous protein expression, where E. coli is preferred due to its rapid growth at high cell density, relatively inexpensive growth substrates, well-established genetic background, and availability of commercial vectors and expression strains .

How should recombinant R07E5.13 be stored and handled?

For optimal stability, recombinant R07E5.13 should be:

• Stored at -20°C/-80°C upon receipt

• Aliquoted to avoid repeated freeze-thaw cycles

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

• Supplemented with 5-50% glycerol (final concentration) for long-term storage

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

What strategies should be employed to optimize soluble expression of recombinant R07E5.13?

Optimizing soluble expression requires a systematic approach using experimental design methodology:

• Employ factorial design to evaluate multiple variables simultaneously:

  • Medium composition (yeast extract, tryptone, salt concentration)

  • Carbon source (glucose vs. glycerol concentration)

  • Induction parameters (IPTG concentration, induction timing)

  • Post-induction temperature

  • Antibiotic concentration

• Specifically for R07E5.13 and similar UPF0041 proteins, consider starting with these conditions that have proven effective for other recombinant proteins:

  • Growth until an OD600 of 0.8

  • Induction with 0.1 mM IPTG

  • Expression for 4 hours at 25°C

  • Medium containing 5 g/L yeast extract, 5 g/L tryptone, 10 g/L NaCl, 1 g/L glucose

• Validate optimized conditions through triplicate experiments, measuring both yield and functional activity to ensure proper folding .

What experimental approaches help determine if recombinant R07E5.13 retains its native structure and function?

Assessing native structure and function requires multiple complementary techniques:

• Primary structure verification:

  • Mass spectrometry to confirm molecular weight

  • N-terminal sequencing to verify correct processing

• Secondary/tertiary structure assessment:

  • Circular dichroism (CD) spectroscopy

  • Intrinsic fluorescence measurements

  • Limited proteolysis patterns compared to native protein

• Functional assays:

  • If the mitochondrial pyruvate carrier function is confirmed, measure pyruvate transport using reconstituted liposomes

  • Protein-protein interaction studies with known binding partners

  • Cell-based functional complementation in mutant systems

When designing these experiments, researchers should implement statistical approaches to evaluate results, as employed in optimization of heterologous protein production systems .

How can structural studies of R07E5.13 inform its proposed function in vesicle trafficking?

Recent research suggests UPF0041 family proteins may function as cargo receptors in vesicle trafficking pathways . To investigate this:

• Employ comparative structural analysis with known cargo receptors:

  • Perform hidden Markov model profile-to-profile searches to identify structural similarities with established receptors like KDEL/Erd2

  • Analyze the seven transmembrane helices common to this protein family

  • Map conserved residues onto structural models to identify potential functional sites

• Design mutagenesis experiments targeting:

  • Residues conserved across UPF0041 family members

  • Regions corresponding to cargo-binding domains in homologous proteins

  • Membrane-spanning domains potentially involved in vesicle formation

• Validate structural predictions through:

  • X-ray crystallography or cryo-EM studies of purified R07E5.13

  • Molecular dynamics simulations to assess conformational changes relevant to cargo binding

  • In vivo fluorescence microscopy tracking vesicle formation and trafficking

What experimental framework should be used to investigate the evolutionary relationships between UPF0041 proteins across species?

UPF0041 proteins exist across eukaryotes and several prokaryotes, presenting an opportunity for evolutionary analysis:

• Sequence-based phylogenetic reconstruction:

  • Collect UPF0041 sequences from diverse species (e.g., C. elegans R07E5.13, S. cerevisiae FMP37)

  • Perform multiple sequence alignment focusing on conserved domains

  • Construct phylogenetic trees using maximum likelihood methods

• Structure-function comparative analysis:

  • Express homologous proteins from evolutionarily distant organisms

  • Compare biochemical properties and activities

  • Map functional divergence onto phylogenetic distances

• Genomic context analysis:

  • Examine gene neighborhood conservation

  • Identify co-evolved gene clusters

  • Analyze intron-exon structures across species

This framework provides insights into functional conservation and specialization across evolution, potentially revealing fundamental aspects of vesicle trafficking mechanisms.

What purification strategy yields the highest purity and recovery of functional R07E5.13?

A multi-step purification approach optimized for His-tagged R07E5.13:

Table 1: Recommended Purification Strategy for R07E5.13

After purification, validate protein functionality using appropriate assays and verify purity by SDS-PAGE (expect >90% purity). For structural studies, additional ion exchange chromatography may be required to achieve >95% purity .

How should researchers troubleshoot expression problems with R07E5.13?

When facing expression challenges with R07E5.13, implement this systematic troubleshooting approach:

• Insoluble protein (inclusion bodies):

  • Reduce expression temperature to 16-20°C

  • Decrease inducer concentration

  • Co-express with molecular chaperones (GroEL/ES, DnaK)

  • Consider fusion partners (SUMO, MBP, TRX)

• Low expression yield:

  • Optimize codon usage for E. coli

  • Evaluate different promoter systems

  • Test various E. coli strains (BL21(DE3), Rosetta, C41/C43)

  • Apply statistical experimental design to systematically optimize culture conditions

• Protein degradation:

  • Add protease inhibitors during purification

  • Test different E. coli strains lacking specific proteases

  • Optimize cell lysis conditions to minimize proteolytic exposure

Experimental design approaches have been shown to significantly improve yields of recombinant proteins, with some systems achieving 250 mg/L of soluble functional protein through optimization .

How can researchers determine whether R07E5.13 functions as a cargo receptor in vesicle trafficking?

To investigate the proposed cargo receptor function:

• Subcellular localization studies:

  • Generate fluorescently tagged R07E5.13 constructs

  • Perform co-localization studies with known vesicle markers

  • Use live-cell imaging to track dynamic trafficking events

• Cargo identification experiments:

  • Perform immunoprecipitation followed by mass spectrometry

  • Use proximity labeling techniques (BioID, APEX) to identify proximal proteins

  • Develop in vitro binding assays with candidate cargo molecules

• Genetic and cellular approaches:

  • Generate knockout/knockdown models in C. elegans

  • Perform rescue experiments with wild-type and mutant versions

  • Analyze vesicular transport defects using fluorescent cargo markers

The prediction that R07E5.13 may function similarly to KDEL receptors suggests examining its potential role in protein trafficking between cellular compartments such as the endoplasmic reticulum, Golgi, or mitochondria, given its annotation as a probable mitochondrial pyruvate carrier .

What structural features distinguish R07E5.13 from other members of the UPF0041 protein family?

Comparative analysis of UPF0041 family members reveals:

What are the most promising research directions for R07E5.13?

Future research on R07E5.13 should prioritize:

• Definitive functional characterization:

  • Confirm or refute its role as a mitochondrial pyruvate carrier

  • Investigate potential cargo receptor functions in vesicle trafficking

  • Determine if it has dual or context-dependent functions

• Structural biology approaches:

  • Solve the three-dimensional structure using cryo-EM or X-ray crystallography

  • Perform molecular dynamics simulations to understand conformational changes

  • Map functional residues for cargo binding and transport

• Physiological relevance:

  • Generate C. elegans models with modified R07E5.13

  • Investigate phenotypic consequences of mutations

  • Explore potential implications for human homologs in health and disease