Recombinant UPF0133 protein SAG1747 (SAG1747)

What is UPF0133 protein SAG1747 and what organism does it originate from?

UPF0133 protein SAG1747 is a member of the Uncharacterized Protein Family (UPF) 0133 found in Streptococcus agalactiae, a Gram-positive bacterium also known as Group B Streptococcus (GBS). This protein belongs to a family of bacterial proteins with specific functions that are not yet fully characterized, similar to other UPF proteins such as UPF0397 protein SAG1634 . Streptococcus agalactiae is an important human pathogen responsible for neonatal infections and is also a cause of infection in immunocompromised adults and the elderly.

Based on similar proteins in the Streptococcus genome, UPF0133 protein SAG1747 likely consists of approximately 150-200 amino acids, although the exact length may vary. These proteins often have transmembrane domains suggesting they may be involved in membrane transport or signaling pathways.

What are the predicted structural characteristics of UPF0133 protein SAG1747?

While detailed structural information about UPF0133 protein SAG1747 is not directly available in the literature, comparative analysis with similar bacterial proteins like UPF0397 protein SAG1634 provides insights into its likely structural features. Based on these comparisons, UPF0133 protein SAG1747 likely contains:

• Multiple hydrophobic regions that may form transmembrane helices

• Conserved domains characteristic of the UPF0133 family

• A structure optimized for membrane association or integration

• Secondary structure elements including alpha helices and beta sheets in a pattern typical for this protein family

Similar proteins like UPF0397 protein SAG1634 show extensive hydrophobic regions in their amino acid sequences, suggesting membrane association . The structural integrity of UPF0133 protein SAG1747 would be critical for its function, and any recombinant version should maintain these structural features.

What experimental approaches are suitable for functional characterization of UPF0133 protein SAG1747?

Functional characterization of UPF0133 protein SAG1747 requires multiple complementary approaches:

• Genetic Approaches:

  • Gene knockout/knockdown studies in Streptococcus agalactiae

  • Complementation assays to verify phenotype rescue

  • Conditional expression systems to study essential gene functions

• Biochemical Characterization:

  • Substrate binding assays to identify interaction partners

  • Enzymatic activity assays based on predicted function

  • Membrane association studies using fractionation techniques

• Structural Biology Methods:

  • X-ray crystallography or NMR spectroscopy for high-resolution structure

  • Cryo-electron microscopy for larger complexes

  • Hydrogen-deuterium exchange mass spectrometry for dynamic information

For membrane-associated proteins like UPF0133 protein SAG1747, functional reconstitution in liposomes or nanodiscs can provide valuable insights into their native activities in a membrane environment. This approach has been successfully used for similar bacterial membrane proteins to preserve their functional state.

What expression systems are optimal for producing Recombinant UPF0133 protein SAG1747?

The choice of expression system for Recombinant UPF0133 protein SAG1747 depends on research objectives, required protein yield, and downstream applications. Based on experiences with similar recombinant proteins, these are the recommended systems:

E. coli expression systems, particularly BL21(DE3) or Rosetta strains, are commonly the first choice for initial characterization studies of bacterial proteins like UPF0133 protein SAG1747. Similar proteins like UPF0397 protein SAG1634 have been successfully expressed in E. coli with N-terminal His tags for purification . For membrane proteins, specialized E. coli strains like C41(DE3) or C43(DE3) designed for membrane protein expression may yield better results.

How can signal peptides be optimized for expression of UPF0133 protein SAG1747?

Selecting appropriate signal peptides is crucial for proper localization and secretion of recombinant proteins like UPF0133 protein SAG1747. Recent research demonstrates that molecule-specific signal peptide optimization can increase recombinant protein production yields by ≥1.8× compared to standard industry systems .

Signal peptides consist of three regions: the N-region (positively charged), H-region (hydrophobic), and C-region (polar) followed by a cleavage site. For optimal expression of UPF0133 protein SAG1747, consider these methodological guidelines:

• Signal Peptide Design Principles:

  • Average optimal size for each domain: N = 5AA, H = 12AA, and C = 5AA

  • Place specific constraints on C-domain creation to enhance functionality

  • Consider synthetic signal peptides created according to domain-based design rules

• Testing Strategy:

  • Screen multiple signal peptides in parallel

  • Evaluate both secretion efficiency and total protein yield

  • Consider signal peptide-product combinations specific to your expression system

• Recommended Signal Peptides for Different Expression Systems:

  • E. coli: PelB, OmpA, DsbA

  • Mammalian: Igκ leader sequence, IL-2 signal sequence, tPA

  • Insect cells: Honeybee melittin signal sequence, gp67 signal peptide

The performance of signal peptides is highly product-specific, so a rational screening approach is recommended rather than relying on a single "universal" signal peptide .

What purification strategy yields the highest purity for Recombinant UPF0133 protein SAG1747?

Purification of Recombinant UPF0133 protein SAG1747 typically requires a multi-step approach to achieve high purity. Based on purification strategies for similar proteins, here's a recommended purification workflow:

Multi-step Purification Protocol:

• Initial Capture:

  • Immobilized Metal Affinity Chromatography (IMAC) using Ni-NTA for His-tagged protein

  • Buffer: Tris/PBS-based buffer, pH 8.0 with 6% Trehalose to enhance stability

  • Consider adding low concentrations of imidazole (10-20 mM) to reduce non-specific binding

• Intermediate Purification:

  • Ion Exchange Chromatography (IEX) based on the theoretical pI of SAG1747

  • Size Exclusion Chromatography (SEC) to separate monomeric protein from aggregates

• Polishing Step:

  • Second SEC run or Hydrophobic Interaction Chromatography (HIC)

For membrane-associated proteins like UPF0133 protein SAG1747, consider adding appropriate detergents during purification (such as 0.1% Triton X-100 or 0.05% DDM) to maintain solubility. Purity should be assessed by SDS-PAGE, with expected purity greater than 90% after the complete purification process .

How can post-translational modifications of UPF0133 protein SAG1747 be analyzed?

Analysis of post-translational modifications (PTMs) in UPF0133 protein SAG1747 requires specialized methodologies:

Mass Spectrometry-Based Approaches:

• Bottom-up Proteomics:

  • Enzymatic digestion (typically trypsin) followed by LC-MS/MS analysis

  • Database searching with variable modification parameters

  • PTM-specific enrichment strategies before MS analysis

• Top-down Proteomics:

  • Analysis of intact protein to preserve PTM combinations

  • High-resolution instruments (Orbitrap, FT-ICR) needed

  • Electron-transfer dissociation (ETD) preserves labile modifications

PTM-Specific Detection Methods:

For bacterial proteins like UPF0133 protein SAG1747, phosphorylation and acetylation may be particularly relevant, as these modifications have been implicated in bacterial signaling and gene regulation. The ubiquitin-proteasome system analysis approach used for studying proteins like Sgf73/ataxin-7 can be adapted for UPF0133 protein SAG1747 by employing CuSO₄-inducible expression of hexahistidine-tagged ubiquitin .

What protein-protein interactions might UPF0133 protein SAG1747 participate in?

Understanding the protein-protein interactions (PPIs) of UPF0133 protein SAG1747 provides insights into its biological function. While specific interaction data for UPF0133 protein SAG1747 is limited, methodological approaches to identify and characterize its interactome include:

• Affinity Purification-Mass Spectrometry (AP-MS):

  • Express tagged SAG1747 in Streptococcus agalactiae or heterologous system

  • Purify using tag affinity (e.g., His-tag on Ni-NTA)

  • Identify co-purifying proteins by MS

  • Validate interactions by reciprocal pull-downs

• Yeast Two-Hybrid (Y2H) Screening:

  • Screen SAG1747 against a Streptococcus agalactiae genomic library

  • Confirm interactions with complementary methods

• Proximity-dependent Biotin Identification (BioID):

  • Fuse SAG1747 to a biotin ligase

  • Identify neighboring proteins that become biotinylated

  • Particularly useful for transient interactions

• Crosslinking Mass Spectrometry (XL-MS):

  • Use chemical crosslinkers to capture interacting partners

  • Identify crosslinked peptides by MS

Based on functional predictions and similar proteins, UPF0133 protein SAG1747 might interact with components of membrane transport systems, regulatory proteins involved in stress response, proteins involved in cell wall biosynthesis, or virulence-associated factors in Streptococcus agalactiae.

How does UPF0133 protein SAG1747 relate to bacterial pathogenicity?

The potential role of UPF0133 protein SAG1747 in Streptococcus agalactiae pathogenicity can be investigated through several research approaches:

• Comparative Genomics:

  • Analyze conservation of SAG1747 across pathogenic and non-pathogenic strains

  • Examine genomic context for association with virulence-related gene clusters

  • Identify potential horizontal gene transfer events

• Infection Models:

  • Compare wild-type and SAG1747 knockout strains in cellular invasion assays

  • Evaluate adherence to host cells and tissues

  • Assess immune response triggered by recombinant SAG1747

• Gene Expression Analysis:

  • Examine expression patterns during different phases of infection

  • Compare expression in response to host defense mechanisms

  • Identify regulatory elements controlling SAG1747 expression

• Structural Homology:

  • Compare with known virulence factors

  • Identify potential binding domains for host receptors

  • Predict functional roles based on structural motifs

If UPF0133 protein SAG1747, like other membrane proteins in pathogenic bacteria, contributes to pathogenicity, it may represent a potential target for antimicrobial development. Recombinant expression and purification of this protein would enable screening for small molecules that could inhibit its function and potentially reduce bacterial virulence.

What analytical methods are suitable for characterizing the structure of UPF0133 protein SAG1747?

Comprehensive structural characterization of UPF0133 protein SAG1747 requires multiple analytical techniques:

For membrane proteins like UPF0133 protein SAG1747, additional considerations include the need for appropriate detergents or membrane mimetics to maintain native structure. Reconstitution into nanodiscs or liposomes prior to structural analysis can provide a more native-like environment for functional studies.

The storage and handling conditions should be carefully optimized. For proteins similar to UPF0133 protein SAG1747, storage in Tris/PBS-based buffer with 6% Trehalose at pH 8.0 may be suitable, with aliquoting to avoid repeated freeze-thaw cycles .

How can the membrane association of UPF0133 protein SAG1747 be experimentally verified?

Verifying the membrane association of UPF0133 protein SAG1747 requires specialized experimental approaches:

• Cellular Fractionation:

  • Separate bacterial cellular components (cytoplasm, membranes)

  • Western blot analysis of fractions using anti-SAG1747 antibodies

  • Compare distribution with known membrane and cytosolic markers

• Fluorescence Microscopy:

  • Create fluorescent protein fusions (e.g., GFP-SAG1747)

  • Visualize localization in bacterial cells

  • Co-localization with membrane-specific dyes

• Membrane Protein Extraction:

  • Differential detergent extraction methods

  • Phase separation techniques (Triton X-114 partitioning)

  • Alkaline carbonate extraction resistance test

• Liposome Binding Assays:

  • Prepare liposomes with bacterial membrane-like composition

  • Incubate with purified SAG1747

  • Assess binding by flotation assays or surface plasmon resonance

• Protease Protection Assays:

  • Treat intact bacterial cells or membrane vesicles with proteases

  • Analyze protected fragments by Western blot

  • Map topology of membrane-embedded regions

For recombinant expression, fusion with a cleavable signal peptide can improve targeting to membranes, with selective optimization of signal peptides potentially increasing expression yields by ≥1.8× compared to standard systems .

How can I determine if UPF0133 protein SAG1747 has enzymatic activity?

Investigating potential enzymatic activities of UPF0133 protein SAG1747 requires a systematic approach:

• Bioinformatic Predictions:

  • Sequence analysis for conserved catalytic motifs

  • Structural homology to known enzymes

  • Analysis of conserved residues across species

• General Activity Screening:

  • Test common enzymatic activities (hydrolase, transferase, oxidoreductase)

  • Use colorimetric or fluorescent assays for high-throughput screening

  • Assess activity under various conditions (pH, temperature, cofactors)

• Substrate Identification:

  • Metabolite profiling comparing wild-type and knockout strains

  • Untargeted approaches using metabolomics

  • Targeted assays based on predicted function

• Mechanistic Studies:

  • Site-directed mutagenesis of predicted catalytic residues

  • Kinetic analysis with identified substrates

  • Inhibitor studies to characterize active site

• Structural Approaches for Activity Determination:

  • Co-crystallization with substrates or substrate analogs

  • NMR-based ligand screening

  • Hydrogen-deuterium exchange to identify substrate binding regions

When establishing enzymatic assays, it's important to ensure that the recombinant UPF0133 protein SAG1747 maintains its native structure, potentially requiring specific detergents or membrane environments for optimal activity if it's a membrane-associated protein.

Why might UPF0133 protein SAG1747 show reduced solubility during expression?

Recombinant UPF0133 protein SAG1747 may exhibit solubility issues during expression, particularly if it contains membrane-associated domains. Understanding the causes and remedies for reduced solubility is essential:

Common Causes of Reduced Solubility:

• Membrane-Associated Nature:

  • Hydrophobic regions designed to interact with lipid bilayers

  • Poor folding in aqueous environments

• Expression System Limitations:

  • Improper folding due to rapid overexpression

  • Lack of appropriate chaperones or folding machinery

• Buffer Incompatibility:

  • Insufficient ionic strength

  • Inappropriate pH relative to protein pI

  • Absence of stabilizing additives

Methodological Solutions to Improve Solubility:

For proteins similar to UPF0133 protein SAG1747, expressing in a Tris/PBS-based buffer with 6% Trehalose at pH 8.0 has proven effective for maintaining solubility and stability .

How can I overcome aggregation issues with Recombinant UPF0133 protein SAG1747?

Protein aggregation is a common challenge when working with recombinant proteins like UPF0133 protein SAG1747. Addressing aggregation requires systematic approaches at different stages:

During Expression:

• Fusion Partner Strategy:

  • Fusion with solubility-enhancing tags (MBP, SUMO, Trx)

  • Cleavable tags using precision protease recognition sites

• Expression Conditions:

  • Reduce expression rate by lowering temperature (16-20°C)

  • Pulse-expression with defined recovery periods

During Purification:

• Buffer Optimization:

  • Screen additives systematically using Differential Scanning Fluorimetry

  • Test various detergents at concentrations above their CMC for membrane-associated regions

• Purification Strategy:

  • Include size exclusion chromatography to remove aggregates

  • Consider on-column refolding protocols during affinity purification

Post-Purification Stabilization:

• Osmolytes and Stabilizers:

  • Add 6% Trehalose to storage buffer

  • Include 5-50% glycerol for long-term storage

  • Consider 0.3-0.5M L-arginine for suppressing protein-protein interactions

• Storage Conditions:

  • Aliquot to prevent repeated freeze-thaw cycles

  • Store at -20°C/-80°C for long-term stability

  • Consider lyophilization with appropriate excipients

For monitoring aggregation, methods such as Dynamic Light Scattering (DLS) for real-time detection and Size Exclusion Chromatography (SEC) for quantifying soluble aggregate content are essential quality control steps.

What strategies can improve yield for difficult-to-express UPF0133 protein SAG1747?

Optimizing the yield of difficult-to-express proteins like UPF0133 protein SAG1747 requires a multi-faceted approach:

Gene and Vector Design Strategies:

• Codon Optimization:

  • Adapt codon usage to expression host

  • Remove rare codons, especially consecutive ones

  • Optimize GC content and remove secondary structures in mRNA

• Promoter Selection:

  • Test various promoter strengths (T7, tac, araBAD)

  • Consider auto-induction systems for gentler expression

• Signal Peptide Optimization:

  • Implement molecule-specific signal peptide optimization

  • Test multiple signal peptides with defined N-, H-, and C-regions

  • This approach can increase yields by ≥1.8× compared to standard systems

Expression Condition Optimization:

• Host Selection:

  • Screen multiple E. coli strains (BL21(DE3), C41/C43, Rosetta, SHuffle)

  • Consider specialized strains for membrane proteins

  • Test eukaryotic systems for complex proteins

• Culture Conditions:

  • Optimize media composition (LB, TB, 2xYT, EnPresso)

  • Test different induction ODs (0.4-0.6, 0.8-1.0, >1.2)

  • Vary induction times and temperatures

• Co-expression Strategies:

  • Add chaperones to assist folding

  • Include rare tRNA-encoding plasmids

  • Co-express protein partners if known

For membrane-associated proteins like UPF0133 protein SAG1747, testing different detergents for extraction and purification can significantly impact final yield. A systematic approach testing a panel of detergents at various concentrations is recommended to identify optimal solubilization conditions.