Recombinant Yersinia pseudotuberculosis serotype O:1b UPF0283 membrane protein YpsIP31758_1791 (YpsIP31758_1791)

What is YpsIP31758_1791 and what organism does it come from?

YpsIP31758_1791 is a membrane protein encoded in the genome of Yersinia pseudotuberculosis serotype O:1b strain IP31758. This particular strain was isolated during Far East scarlet-like fever (FESLF) epidemics that swept through the Pacific coastal region of Russia in the late 1950s . Y. pseudotuberculosis IP31758 is noteworthy because it causes a set of clinical symptoms substantially different from classical pseudotuberculosis, including erythematous skin rash, desquamation, exanthema, hyperhemic tongue, and toxic shock syndrome . This distinct clinical presentation led to the designation "Far East scarlet-like fever" due to its similarities with scarlet fever caused by group A streptococci.

How does YpsIP31758_1791 fit into the genomic context of Y. pseudotuberculosis IP31758?

The gene encoding YpsIP31758_1791 is part of the unique gene pool of Y. pseudotuberculosis IP31758, which contains more than 260 strain-specific genes compared to other Y. pseudotuberculosis strains . The genome of Y. pseudotuberculosis IP31758 includes individual physiological capabilities and virulence determinants, with a significant proportion being horizontally acquired, likely originating from Enterobacteriaceae and other soil-dwelling bacteria that persist in the same ecological niche . This genomic context suggests that YpsIP31758_1791 may contribute to the unique pathogenic properties of this strain, though its specific role has not been definitively characterized.

What expression systems are optimal for recombinant production of YpsIP31758_1791?

Recombinant expression of YpsIP31758_1791 has been successfully achieved in E. coli expression systems with an N-terminal His-tag for purification purposes . Based on current practices in membrane protein research, several expression strategies can be considered:

For optimal expression, induction conditions should be carefully optimized, typically using lower temperatures (16-20°C), appropriate IPTG concentrations, and extended induction times to facilitate proper membrane integration .

What are effective methods for isolating and purifying YpsIP31758_1791?

The isolation and purification of membrane proteins like YpsIP31758_1791 present unique challenges. Several methodological approaches can be employed:

Traditional detergent-based approaches:

• Membrane isolation: Separate bacterial membranes using ultracentrifugation techniques

• Solubilization: Extract the protein using appropriate detergents (DDM, LDAO, or CHAPS)

• Affinity purification: Utilize immobilized metal affinity chromatography (IMAC) to purify His-tagged protein

• Size exclusion chromatography: Further purify and analyze oligomeric state

Detergent-free approaches:
Recent advancements allow for detergent-free isolation of membrane proteins directly from cell membranes . This can be achieved using:

• Amphipathic polymers: Synthetic polymers can extract membrane proteins along with their native lipid environment

• Lipid nanodiscs: Reconstitute purified protein into nanodiscs for structural and functional studies

• Styrene-maleic acid lipid particles (SMALPs): Direct extraction of membrane proteins within native lipid environments

These detergent-free approaches have the advantage of maintaining the protein in a more native-like environment, which can be crucial for structural integrity and functional studies .

How can researchers verify the structural integrity of purified YpsIP31758_1791?

After purification, the structural integrity and proper folding of YpsIP31758_1791 should be assessed using multiple complementary techniques:

• Circular dichroism (CD) spectroscopy: Evaluates secondary structure content

• Fluorescence spectroscopy: Monitors tertiary structure through intrinsic tryptophan fluorescence

• Size exclusion chromatography coupled with multi-angle light scattering (SEC-MALS): Determines oligomeric state

• Thermal shift assays: Assesses protein stability under different buffer conditions

• Limited proteolysis: Probes for properly folded, compact domains resistant to proteolytic degradation

An integrated approach using multiple techniques provides the most robust assessment of structural integrity for membrane proteins like YpsIP31758_1791.

What high-resolution structural techniques are suitable for studying YpsIP31758_1791?

Due to the challenges inherent in membrane protein structural biology, several complementary approaches can be employed:

X-ray crystallography:
While traditionally challenging for membrane proteins, advances in crystallization techniques using lipidic cubic phases or bicelles have improved success rates . The critical steps include:

• Screening numerous crystallization conditions

• Optimizing detergent and lipid composition

• Using crystallization chaperones (antibody fragments, fusion partners)

• Employing microfocus beamlines for data collection from small crystals

Cryo-electron microscopy (cryo-EM):
Recent advances have made cryo-EM particularly valuable for membrane protein structure determination :

• Single-particle analysis for larger proteins or complexes (>100 kDa)

• Tomography for studying the protein in its cellular context

• Electron crystallography for 2D crystals, similar to the approach used for bacteriorhodopsin

NMR spectroscopy:
Solution and solid-state NMR can provide valuable structural and dynamic information :

• Solution NMR for smaller membrane proteins in detergent micelles

• Solid-state NMR for proteins in lipid bilayers or other membrane mimetics

• Particularly valuable for studying protein dynamics and ligand interactions

How can computational methods complement experimental structural studies of YpsIP31758_1791?

Computational approaches provide valuable insights when experimental structural data is limited:

• Homology modeling: Building structural models based on related proteins with known structures

• Ab initio modeling: Predicting structure from sequence alone, increasingly powerful with methods like AlphaFold

• Molecular dynamics simulations: Investigating protein behavior in membrane environments

• Docking studies: Predicting interactions with potential ligands or other proteins

• Evolutionary coupling analysis: Identifying residue contacts through co-evolutionary patterns

These computational methods can guide experimental design and provide working models until high-resolution experimental structures are available.

What experimental approaches can be used to determine the function of YpsIP31758_1791?

As YpsIP31758_1791 belongs to an uncharacterized protein family (UPF0283) , multiple complementary approaches are needed to elucidate its function:

Genetic approaches:

• Gene knockout/knockdown: Generate deletion mutants and assess phenotypic changes

• Complementation studies: Reintroduce wild-type or mutant versions to confirm phenotype

• Suppressor screens: Identify genes that can compensate for YpsIP31758_1791 loss

Biochemical approaches:

• Protein-protein interaction studies: Identify binding partners through pull-downs, crosslinking, or two-hybrid systems

• Metabolite binding assays: Test for interactions with potential substrates or signaling molecules

• Enzymatic activity tests: Screen for potential catalytic functions

Structural biology approaches:

• Substrate co-crystallization: Attempt to crystallize the protein with potential ligands

• NMR binding studies: Monitor chemical shift perturbations upon ligand addition

• Hydrogen-deuterium exchange mass spectrometry: Map protein dynamics and binding interfaces

Systems biology approaches:

• Transcriptomics: Compare gene expression patterns between wild-type and knockout strains

• Proteomics: Identify changes in protein abundance or modifications

• Metabolomics: Detect metabolic changes associated with protein loss or overexpression

How might YpsIP31758_1791 contribute to the unique pathogenesis of Y. pseudotuberculosis IP31758?

Y. pseudotuberculosis IP31758 causes Far East scarlet-like fever with symptoms distinct from classical pseudotuberculosis . While the specific contribution of YpsIP31758_1791 to pathogenesis remains unknown, several possibilities exist:

• Membrane integrity and homeostasis: As a membrane protein, it may regulate membrane properties critical during infection

• Transport function: It might transport molecules essential for survival in host tissues

• Signaling: It could participate in sensing host environmental cues

• Host interaction: It may directly interact with host cells or molecules

Y. pseudotuberculosis IP31758 contains unique virulence determinants including two novel plasmids phylogenetically unrelated to all currently reported Yersinia plasmids . The strain also possesses an icm/dot type IVB secretion system found on the larger plasmid, which could contribute to immunomodulatory capabilities . YpsIP31758_1791 might function in conjunction with these unique virulence systems, potentially contributing to the distinctive clinical presentation of FESLF.

How does YpsIP31758_1791 compare to similar membrane proteins in other Yersinia species?

Comparative genomic analysis between Y. pseudotuberculosis IP31758 and other Yersinia species reveals significant differences. Y. pseudotuberculosis displays more heterogeneous population genetics compared to Y. pestis, which shows limited genetic diversity . This suggests that proteins like YpsIP31758_1791 might have evolved distinct functions in different Yersinia lineages.

Specific comparisons should examine:

• Presence of homologs in other Yersinia species and strains

• Sequence conservation and divergence patterns

• Genomic context and potential operon structures

• Expression patterns under different conditions

This comparative approach can provide insights into the evolutionary history and potential specialized functions of YpsIP31758_1791 in Y. pseudotuberculosis IP31758.

How can membrane localization and topology of YpsIP31758_1791 be determined?

Understanding the precise membrane localization and topology of YpsIP31758_1791 is critical for functional studies. Several complementary experimental approaches can be employed:

Subcellular fractionation techniques:

• Isopycnic density gradient centrifugation to separate inner and outer membranes

• Western blotting of fractionated membranes using antibodies against YpsIP31758_1791

• Mass spectrometry-based proteomic analysis of membrane fractions

Topology mapping:

• Cysteine scanning mutagenesis with accessibility assays

• Protease protection assays to determine which regions are accessible from different sides of the membrane

• Fluorescence quenching experiments with position-specific labels

• Epitope tagging at different positions followed by accessibility testing

Microscopy approaches:

• Immunogold electron microscopy for high-resolution localization

• Super-resolution fluorescence microscopy with specific antibodies

• Fluorescent protein fusions (ensuring functionality is preserved)

The combination of these approaches will provide a comprehensive understanding of how YpsIP31758_1791 is oriented and positioned within the bacterial membrane.

What protein-protein interactions might be critical for YpsIP31758_1791 function?

Membrane proteins frequently function within complexes or interact transiently with other proteins. To identify potential interaction partners of YpsIP31758_1791:

• Affinity purification coupled with mass spectrometry (AP-MS):

  • Use His-tagged YpsIP31758_1791 as bait to pull down interaction partners

  • Employ crosslinking to capture transient interactions

  • Compare results from different conditions to identify context-specific interactions

• Bacterial two-hybrid or split-protein complementation assays:

  • Screen for binary interactions with candidate proteins

  • Perform unbiased screens against libraries of Y. pseudotuberculosis proteins

• Proximity labeling approaches:

  • Fusion of YpsIP31758_1791 to enzymes like BioID or APEX2

  • Label proteins in close proximity in living cells

  • Identify labeled proteins by mass spectrometry

• Co-immunoprecipitation studies:

  • Use antibodies against YpsIP31758_1791 or potential interaction partners

  • Confirm interactions identified through other methods

Understanding the protein interaction network will provide critical insights into potential functions and regulatory mechanisms.

How might post-translational modifications affect YpsIP31758_1791 function?

As a bacterial membrane protein, YpsIP31758_1791 may undergo several post-translational modifications that could affect its function and regulation:

Potential modifications:

• Phosphorylation of serine, threonine, or tyrosine residues

• Lipid modifications affecting membrane anchoring

• Disulfide bond formation in regions exposed to the periplasm

• Proteolytic processing that might activate or regulate the protein

Methods to identify modifications:

• Mass spectrometry-based proteomic approaches:

  • Bottom-up proteomics for identification of modification sites

  • Top-down proteomics for characterizing proteoforms

  • Enrichment strategies for specific modifications

• Functional studies of modification sites:

  • Site-directed mutagenesis of potential modification sites

  • Comparison of protein function before and after treatment with modifying enzymes

  • Structural studies to determine the impact of modifications on protein conformation

Understanding these modifications could provide insights into regulatory mechanisms and environmental responsiveness of YpsIP31758_1791.

How might systems biology approaches enhance our understanding of YpsIP31758_1791?

Integrating multiple omics approaches can provide a comprehensive understanding of YpsIP31758_1791 function within the broader cellular context:

• Transcriptomics:

  • RNA-seq comparing wild-type and YpsIP31758_1791 mutant strains under various conditions

  • Identification of genes co-regulated with YpsIP31758_1791

  • Analysis of transcriptional changes in response to environmental stimuli

• Proteomics:

  • Quantitative proteomics to identify changes in protein abundance

  • Interactomics to map protein-protein interaction networks

  • Phosphoproteomics to identify signaling pathways affected by YpsIP31758_1791

• Metabolomics:

  • Global metabolite profiling to identify metabolic pathways affected

  • Targeted analysis of specific metabolites potentially transported by YpsIP31758_1791

  • Flux analysis to determine changes in metabolic pathway activities

• Integrative data analysis:

  • Multi-omics data integration to identify coherent patterns

  • Network analysis to position YpsIP31758_1791 within cellular networks

  • Predictive modeling of system behavior with and without YpsIP31758_1791

This systems-level approach will provide a holistic view of YpsIP31758_1791 function and its contribution to Y. pseudotuberculosis biology.

What role might YpsIP31758_1791 play in bacterial adaptation to host environments?

Y. pseudotuberculosis must rapidly adjust its lifestyle and pathogenesis upon host entry . As a membrane protein, YpsIP31758_1791 might play roles in this adaptation process:

• Temperature-responsive regulation:

  • Examine expression changes between environmental (25°C) and host (37°C) temperatures

  • Assess membrane localization and function at different temperatures

  • Determine if protein undergoes structural changes in response to temperature

• Host immune evasion:

  • Test if YpsIP31758_1791 contributes to resistance against host defense mechanisms

  • Examine interactions with host immune components

  • Assess its role in bacterial survival within phagocytes

• Metabolic adaptation:

  • Investigate if YpsIP31758_1791 facilitates nutrient acquisition in host environments

  • Examine its role in the "acetate switch" or other metabolic reprogramming events

  • Test growth phenotypes in different nutrient conditions

• Virulence regulation:

  • Determine if YpsIP31758_1791 affects expression or function of virulence factors

  • Assess its contribution to bacterial colonization and dissemination

  • Test virulence of deletion mutants in animal models

Understanding these adaptation mechanisms could provide insights into Y. pseudotuberculosis pathogenesis and potentially identify new therapeutic targets.