Recombinant Salmonella dublin UPF0761 membrane protein yihY (yihY)

What is the UPF0761 membrane protein yihY and why is it important in Salmonella research?

The UPF0761 membrane protein yihY is a 290-amino acid protein found in various Salmonella strains including Salmonella dublin and Salmonella choleraesuis. It belongs to the UPF0761 protein family, which consists of uncharacterized proteins with potential functional significance. The protein is embedded in the bacterial membrane, suggesting a possible role in cellular processes such as transport, signaling, or structural integrity. Research on yihY contributes to our understanding of Salmonella pathogenesis and potential therapeutic targets for Salmonella infections. The protein's conservation across multiple Salmonella strains indicates evolutionary importance and possible functional relevance in bacterial survival mechanisms .

What is the amino acid sequence of Salmonella dublin UPF0761 membrane protein yihY?

The complete amino acid sequence of Salmonella dublin UPF0761 membrane protein yihY consists of 290 amino acids as follows:

MLKTVHQKAGRHTRPVRAWLKLLWQRIDEDNMTTLAGNLAYVSLLSLVPLIAVVFALFAA
FPMFSDVSIQLRHFIFANFMPATGDVIQRYIEQFVANSNKMTAVGACGLIVTALLLMYAI
DSALNTIWRSKRTRPKVYSFAVYWMILTLGPLLAGASLAISSYLLSLRWASDLNTVIDNV
LRILPLLLSWISFWLLYSIVPTTRVPNRDALVGAFVAALLFEAGKKGFALYITMFPSYQL
IYGVLAVIPILFVWVYWTWCIVLLGAEITVTLGEYRKLKQAAEQEEADQP

This sequence is identical across recombinant versions from different suppliers and has been confirmed through protein sequencing techniques. The UniProt accession number for Salmonella dublin strain CT_02021853 is B5FP16, which can be used for further bioinformatic analyses and comparative studies .

How do Salmonella dublin and Salmonella choleraesuis yihY proteins compare structurally?

The yihY proteins from Salmonella dublin and Salmonella choleraesuis exhibit high sequence homology, reflecting their evolutionary relationship within the Salmonella genus. Both proteins contain 290 amino acids with identical sequences, suggesting conserved function across these strains. The UniProt entries (B5FP16 for S. dublin and Q57HI9 for S. choleraesuis) provide reference points for structural comparison studies. Both proteins are predicted to contain multiple transmembrane domains consistent with their classification as membrane proteins. While primary sequences appear identical, potential differences may exist in post-translational modifications or protein-protein interactions that could be strain-specific. Comparative structural biology techniques such as X-ray crystallography or cryo-electron microscopy would be necessary to detect subtle structural differences not apparent from sequence analysis alone .

What are the optimal storage conditions for recombinant yihY protein to maintain structural integrity?

For optimal preservation of recombinant yihY protein structural integrity, storage at -20°C to -80°C is recommended for long-term maintenance. The protein should be stored in a Tris-based buffer with 50% glycerol or a Tris/PBS-based buffer with 6% trehalose at pH 8.0, as these conditions have been optimized to stabilize the protein's native conformation. Critically, repeated freeze-thaw cycles must be avoided as they promote protein denaturation and aggregation. For ongoing experiments, working aliquots should be prepared and stored at 4°C for a maximum of one week to minimize degradation. When preparing aliquots, centrifugation prior to opening is recommended to bring contents to the bottom of the vial. For reconstitution of lyophilized preparations, sterile deionized water should be used to achieve a concentration of 0.1-1.0 mg/mL, with glycerol addition (5-50% final concentration) for stabilization. These precise storage parameters ensure experimental reproducibility and maintain protein functionality for downstream applications .

What is the recommended protocol for reconstituting lyophilized recombinant yihY protein?

The recommended protocol for reconstituting lyophilized recombinant yihY protein begins with brief centrifugation of the vial to ensure all material is at the bottom. The lyophilized protein should be reconstituted using deionized sterile water to achieve a concentration between 0.1-1.0 mg/mL. For optimal stability, it is advisable to add glycerol to a final concentration of 5-50%, with 50% being the standard recommendation for long-term storage. After reconstitution, the solution should be gently mixed to ensure complete dissolution without introducing air bubbles that could cause protein denaturation at the air-liquid interface. The reconstituted protein should be aliquoted into smaller volumes to avoid repeated freeze-thaw cycles. Each aliquot should be clearly labeled with the date of reconstitution, concentration, and buffer composition. For immediate experimental use, working aliquots can be maintained at 4°C for up to one week, while remaining aliquots should be stored at -20°C or preferably -80°C for long-term stability .

What expression systems are most effective for producing functional recombinant yihY protein?

E. coli expression systems have proven most effective for producing functional recombinant yihY protein from Salmonella dublin and related strains. This prokaryotic expression platform offers several advantages for membrane protein production including compatibility with the bacterial origin of yihY, established protocols for membrane protein expression, and high protein yields. Commercial preparations typically use E. coli to express full-length yihY (amino acids 1-290) with N-terminal His-tags to facilitate purification via affinity chromatography. When designing expression constructs, codon optimization for E. coli is recommended to enhance expression efficiency. For proper membrane insertion, signal sequences should be preserved. To maintain protein functionality, expression conditions should be optimized with IPTG concentrations of 0.1-1.0 mM and induction temperatures of 16-30°C, with lower temperatures often yielding better folding of membrane proteins. Alternative expression systems such as cell-free systems or yeast platforms may be considered for specialized applications requiring eukaryotic post-translational modifications or when encountering toxicity issues in E. coli .

How can structural characterization of yihY inform potential drug targeting strategies against Salmonella infections?

Structural characterization of yihY presents significant opportunities for rational drug design against Salmonella infections through several approaches. As a membrane protein, yihY may contain unique binding pockets accessible from the extracellular space, making it potentially druggable. Advanced structural determination methods including X-ray crystallography, cryo-electron microscopy, and NMR spectroscopy can reveal these binding sites with atomic-level precision. Molecular dynamics simulations using the full 290-amino acid sequence can further identify conformational changes relevant to function. The high conservation of yihY across Salmonella strains (dublin, choleraesuis, typhimurium) suggests that targeting this protein could provide broad-spectrum activity. Structure-based virtual screening campaigns can leverage the identified binding pockets to discover small molecule inhibitors with high specificity for bacterial over human proteins. Additionally, epitope mapping may reveal surface-exposed regions suitable for antibody targeting, potentially enabling immunotherapy approaches. The membrane localization of yihY also presents opportunities for developing targeted drug delivery systems that specifically recognize and bind to Salmonella cells expressing this protein, potentially increasing antibiotic efficacy while reducing off-target effects .

What methodological approaches can be used to investigate the protein-protein interactions of yihY in Salmonella pathogenesis?

Investigation of yihY protein-protein interactions in Salmonella pathogenesis requires a multi-faceted methodological approach. Pull-down assays using His-tagged recombinant yihY protein can identify direct binding partners from bacterial lysates, with subsequent mass spectrometry analysis for partner identification. Co-immunoprecipitation studies with antibodies specific to yihY can verify these interactions in their native context. For membrane protein interactions, techniques like chemical cross-linking coupled with mass spectrometry are particularly valuable, as they can capture transient interactions within the membrane environment. Bacterial two-hybrid systems adapted for membrane proteins can screen for interaction partners in vivo, while proximity-dependent biotin identification (BioID) techniques can map the wider interactome of yihY. FRET or BRET assays using fluorescently tagged constructs allow real-time monitoring of protein interactions during infection processes. Comparative interactomics between pathogenic and non-pathogenic Salmonella strains can highlight interactions specific to virulence. Computational approaches including protein-protein docking and molecular dynamics simulations complement experimental data by predicting binding interfaces and interaction energetics. These methodologies should be applied in both in vitro systems and infection models to comprehensively characterize the role of yihY interactions in pathogenesis .

What techniques can be used to determine the membrane topology and transmembrane domains of yihY?

Determining the membrane topology and transmembrane domains of yihY requires a strategic combination of computational prediction and experimental validation approaches. Initially, hydropathy analysis and transmembrane prediction algorithms (TMHMM, HMMTOP, Phobius) should be applied to the 290-amino acid sequence to generate preliminary topology models. These in silico predictions can be experimentally validated through several complementary methods. Cysteine scanning mutagenesis, coupled with membrane-impermeable sulfhydryl reagents, can distinguish cytoplasmic from periplasmic regions. Fluorescence protease protection assays, where GFP-fusion constructs are subjected to protease treatment, can define orientation relative to the membrane. Glycosylation mapping, using engineered N-glycosylation sites, provides insights into which regions access the glycosylation machinery. PhoA and GFP fusion reporters with truncated versions of yihY can distinguish cytoplasmic from periplasmic segments based on respective reporter activity. For high-resolution structural determination, techniques such as cryo-electron microscopy of 2D crystals or solid-state NMR of reconstituted protein in nanodiscs are particularly suitable for membrane proteins like yihY. Cross-linking mass spectrometry can identify residues in close proximity, further validating structural models. Together, these approaches provide a comprehensive view of yihY's membrane topology essential for understanding its function .

What are common challenges in achieving high purity of recombinant yihY protein and how can they be addressed?

Common challenges in achieving high purity of recombinant yihY protein include membrane protein solubility issues, contaminating proteins, aggregation, and degradation. These can be systematically addressed through optimization of multiple purification parameters. For solubility challenges, screening different detergents (DDM, LMNG, OG) at varying concentrations is essential, with mild detergents often preserving native structure better than harsh ionic surfactants. Protein aggregation can be minimized by including stabilizing agents such as glycerol (5-20%) or specific lipids in buffers throughout purification. To reduce co-purifying contaminants when using His-tagged constructs, implementing stepped imidazole gradients (10-20-50-250 mM) during affinity chromatography provides better separation than single-step elution. Further purification using ion exchange or size exclusion chromatography can increase purity to >95%. Proteolytic degradation, common with membrane proteins, can be controlled by including protease inhibitor cocktails in all buffers and maintaining samples at 4°C during processing. SDS-PAGE analysis coupled with Western blotting using anti-His antibodies should confirm both purity and identity of the target protein. For particularly challenging preparations, on-column refolding protocols or alternative solubilization strategies such as amphipols or nanodiscs may improve recovery of properly folded protein. Commercial preparations typically achieve >90% purity as determined by SDS-PAGE, providing a benchmark for laboratory-scale purification efforts .

How can researchers optimize antibody-based detection methods for yihY in experimental systems?

Optimizing antibody-based detection methods for yihY requires careful consideration of the protein's membrane localization and conformational integrity. When developing or selecting antibodies, researchers should target either extracellular loops for intact cell applications or unique peptide sequences for denatured samples. For Western blotting applications, sample preparation is critical—membrane proteins require complete solubilization using appropriate detergents (1-2% SDS or 8M urea), with heating limited to 37°C instead of boiling to prevent aggregation. Transfer conditions should be optimized for high molecular weight membrane proteins by using lower methanol concentrations (5-10%) in transfer buffers and extended transfer times (overnight at low voltage). For immunofluorescence microscopy, permeabilization protocols must balance membrane disruption for antibody access with preservation of membrane architecture—Triton X-100 (0.1%) or saponin (0.1-0.5%) are often suitable. When performing immunoprecipitation of yihY, native conformation can be preserved using milder detergents like digitonin (1%) or DDM (0.5-1%). Blocking solutions should contain both protein blockers (5% BSA) and detergents (0.1% Tween-20) to minimize background. Signal amplification systems such as tyramide signal amplification or quantum dots may be necessary for detecting low-abundance yihY expression. For quantitative applications, standard curves using purified recombinant yihY at known concentrations should be included to ensure linear detection ranges .

How might comparative genomics of yihY across Salmonella strains inform evolutionary adaptation and host specificity?

Comparative genomics of yihY across diverse Salmonella strains presents a valuable approach for understanding evolutionary adaptation and host specificity. Sequence analysis across the Salmonella genus—including serovars Dublin, Choleraesuis, Typhimurium, Enteritidis, and others—can reveal conservation patterns indicative of functional constraints or adaptive selection pressures. Particularly informative would be the comparison between host-restricted serovars (S. dublin predominantly in cattle) versus broad-host-range serovars (S. typhimurium) to identify sequence variations potentially associated with host adaptation. Nonsynonymous to synonymous substitution ratio (dN/dS) analysis can highlight residues under positive selection, potentially identifying key functional domains. Genomic context analysis examining the organization of genes surrounding yihY may reveal operonic structures or horizontally transferred genetic elements suggesting functional relationships. Phylogenetic analyses incorporating yihY sequences from multiple Salmonella strains alongside related enterobacteria can reconstruct the evolutionary history of this gene and detect possible instances of horizontal gene transfer. Structural modeling of sequence variants can predict functional consequences of observed polymorphisms. Additionally, correlation analyses between specific yihY variants and known virulence phenotypes or host range restrictions could establish genotype-phenotype relationships informative for developing targeted interventions against specific Salmonella strains .

What potential applications exist for using recombinant yihY protein in vaccine development against Salmonella infections?

Recombinant yihY protein offers several promising avenues for Salmonella vaccine development. As a membrane-associated protein conserved across multiple Salmonella serovars (Dublin, Choleraesuis, Typhimurium), yihY represents a potential broad-spectrum antigen target. Subunit vaccine approaches could utilize purified recombinant yihY protein combined with appropriate adjuvants to stimulate protective immunity. Epitope mapping studies should identify immunodominant regions of the 290-amino acid sequence that generate robust T-cell and B-cell responses. These epitopes could be incorporated into multi-epitope vaccine constructs containing immunogenic segments from various Salmonella antigens. DNA vaccine strategies encoding yihY could provide sustained antigen expression and enhanced cellular immunity. For improved delivery and antigen presentation, recombinant yihY could be incorporated into nanoparticle formulations or virus-like particles that protect the protein from degradation while enhancing uptake by antigen-presenting cells. Live attenuated Salmonella strains over-expressing yihY might generate stronger immune responses against this target. Importantly, vaccination efficacy against Salmonella Dublin should be evaluated in appropriate animal models, particularly cattle, which are natural hosts for this serovar and represent an important reservoir for human infection. Cross-protection studies against multiple Salmonella serovars would determine the breadth of protection conferred by yihY-based vaccines .

How can systems biology approaches integrate yihY function into broader Salmonella pathogenesis networks?

Systems biology approaches can contextually integrate yihY function within comprehensive Salmonella pathogenesis networks through multi-omics data integration and computational modeling. Transcriptomic profiling comparing wild-type and yihY-deficient Salmonella under various infection-relevant conditions (acid stress, macrophage internalization, intestinal environment) can identify co-regulated genes and place yihY within specific stress response pathways. Proteomic interaction networks using techniques like BioID or APEX2 proximity labeling can map the physical interactome of yihY, revealing direct binding partners and protein complexes. Metabolomic analysis of yihY mutants may uncover metabolic pathways affected by this membrane protein, potentially revealing transporter or regulatory functions. Phosphoproteomic analysis can identify signaling cascades influenced by yihY activity. Integration of these multi-omics datasets through computational approaches like weighted gene co-expression network analysis (WGCNA) or Bayesian network modeling can generate testable hypotheses about yihY's functional role. Agent-based modeling incorporating yihY-dependent processes can simulate infection dynamics at different scales—from single-cell to host population levels. Flux balance analysis may reveal metabolic consequences of yihY activity. Machine learning approaches applied to integrated datasets can identify emergent patterns not obvious from individual analyses. These systems-level insights will position yihY within the broader context of Salmonella virulence mechanisms, potentially identifying network vulnerabilities suitable for therapeutic intervention .