Recombinant Salmonella agona UPF0761 membrane protein yihY (yihY)

What is the structural composition of Salmonella agona UPF0761 membrane protein yihY?

The Salmonella agona UPF0761 membrane protein yihY (UniProt: B5EZZ9) is a full-length protein consisting of 290 amino acids. Its primary sequence is: MLKTVHQKAGRPVRAWLKLLWQRIDEDNMTTLAGNLAYVSLLSLVPLIAVVFALFAAFPMFSDVSIQLRHFIFANFMPATGDVIQRYIEQFVANSNKMTAVGACGLIVTALLLMYAIDSALNTIWRSKRTRPKVYSFAVYWMILTLGPLLAGASLAISSYLLSLRWASDLNTVIDNVLRILPLLLSWISFWLLYSIVPTTRVPNRDALVGAFVAALLFEAGKKGFALYITMFPSYQLIYGVLAVIPILFVWVYWTWCIVLLGAEITVTLGEYRKLKQAAEQEEADQP .

The protein's hydrophobic profile and sequence analysis suggest it contains multiple transmembrane domains, consistent with its classification as a membrane protein. Comparative analysis with homologous proteins such as the E. coli UPF0761 membrane protein yihY shows significant sequence conservation in the transmembrane regions, suggesting functional importance of these domains .

What are the recommended storage and handling conditions for recombinant Salmonella agona yihY protein samples?

For optimal stability and activity preservation of recombinant Salmonella agona yihY protein, storage at -20°C is recommended for regular use, while -80°C is preferred for extended storage periods . The protein is typically supplied in a Tris-based buffer with 50% glycerol that has been optimized for this specific protein .

To minimize protein degradation, it is crucial to avoid repeated freeze-thaw cycles. For ongoing experiments, preparing working aliquots that can be stored at 4°C for up to one week is advisable . When reconstituting lyophilized preparations, a brief centrifugation is recommended prior to opening the vial to collect all material at the bottom of the tube. Careful temperature management during experimental procedures is essential as membrane proteins are particularly susceptible to denaturation and aggregation at elevated temperatures .

How does the amino acid sequence of Salmonella agona yihY compare to homologous proteins in other bacterial species?

Key differences include several amino acid substitutions in the transmembrane regions: Salmonella agona yihY contains the sequence "FMPATGDVIQRYIEQFVANSNKMTAVGACGLIVTALLLMYAIDSALNT" while the E. coli variant has "FLPATGDVIQRYIEQFVANSNKMTAVGACGLIVTALLLMYSIDSALNT" . These minor differences may contribute to species-specific membrane interactions or substrate specificity. The high conservation of transmembrane domains across species suggests essential functional roles, while variable regions may reflect adaptations to different environmental niches or host interactions.

What detection methods are commonly used for identifying Salmonella agona in research samples?

Research on Salmonella agona utilizes multiple complementary detection methods to ensure accurate identification. The two primary approaches are culture-based isolation and molecular detection via PCR.

Culture-based methods typically involve:

• Selective enrichment in media such as LB broth

• Plating on selective agars

• Biochemical confirmation tests

• Serotyping to confirm Salmonella agona specifically

PCR-based detection offers higher sensitivity and includes:

• Conventional PCR targeting conserved Salmonella genes

• Real-time PCR for quantitative analysis

• Multiple-locus variable-number tandem repeat analysis (MLVA)

• Whole genome sequencing for definitive identification and strain discrimination

In experimental studies, researchers often employ both methods in parallel, as demonstrated in transmission studies where air samples, pooled fecal samples, and rectal swabs were assessed using both culture and PCR techniques . This combined approach compensates for the limitations of each method, as evidenced by cases where positive samples were detected by PCR but not by culture, or vice versa .

What experimental designs are effective for studying the role of Salmonella agona in airborne bacterial transmission?

Designing rigorous experiments to assess airborne transmission of Salmonella agona requires specialized containment systems and sampling protocols. A proven approach involves using connected isolation cabinets with unidirectional airflow control.

A comprehensive experimental design should include:

• Containment System Configuration:

  • Stainless-steel/glass isolation cabinets connected by air ducts

  • Unidirectional airflow system (from control to sentinel animals, passing through infected subjects)

  • Sealed system with fumigation chambers and rubber gloves for sampling without compromising containment

• Animal Model Selection:

  • Weaned pigs have proven effective as they are natural hosts for Salmonella

  • Groups should include control animals, inoculated animals, and sentinel animals

• Environmental Parameter Control:

  • Temperature maintenance between 24-30°C

  • Relative humidity control between 45-80%

  • Air pressure differentials to ensure unidirectional flow

• Comprehensive Sampling Protocol:

  • Daily collection of air samples using impingers or cyclonic collectors

  • Pooled fecal samples from housing surfaces

  • Individual rectal swabs from all animal groups

  • Serological sampling to detect seroconversion in sentinel animals

• Detection Methodology:

  • Parallel testing using both culture and PCR methods

  • Strain-specific markers (such as nalidixic acid resistance) for tracking experimental strains

  • Regular sampling intervals (daily recommended) throughout the study period

This methodology has successfully demonstrated airborne Salmonella agona transmission in experimental settings, with recovery of the pathogen from air samples and detection of seroconversion in sentinel pigs exposed only via airflow .

How can whole genome sequencing be applied to differentiate between persistent and reintroduced Salmonella agona strains in outbreak investigations?

Whole genome sequencing (WGS) provides powerful resolution for distinguishing between persistent contamination and new introduction events in Salmonella agona outbreak investigations. The methodological approach involves:

• Sequencing Platform Selection:

  • High-quality complete genome assembly requires long-read technologies like Pacific Biosciences RS II Sequencer

  • Illumina platforms can provide complementary short-read data for error correction

• Bioinformatic Analysis Workflow:

  • Reference-based mapping to identify variable sites

  • Single Nucleotide Polymorphism (SNP) analysis to determine genetic distances

  • Phylogenetic reconstruction to establish evolutionary relationships

• Interpretative Framework:

  • Persistent strains typically show limited SNP differences over time (≤10 SNPs)

  • Reintroduced strains show greater genetic divergence

  • Time-scaled phylogenies help calibrate expected mutation rates

This approach was effectively demonstrated in the investigation of two Salmonella Agona outbreaks separated by 10 years (1998 and 2008) that were linked to the same food production facility. Despite the temporal separation, WGS analysis revealed only a mean of eight SNP differences between isolates from both outbreaks, providing strong evidence that the 2008 outbreak involved direct descendants of the 1998 strain rather than a new contamination event . This case illustrates how WGS can differentiate between scenarios that would be indistinguishable using traditional typing methods such as PFGE, which showed identical patterns for both outbreak strains .

What methodologies are most effective for functional characterization of the Salmonella agona yihY membrane protein?

Comprehensive functional characterization of the Salmonella agona yihY membrane protein requires a multi-faceted approach combining structural, biochemical, and genetic techniques:

• Recombinant Expression and Purification:

  • Expression system selection (typically E. coli with appropriate tags)

  • Optimization of solubilization conditions using detergents suitable for membrane proteins

  • Affinity chromatography followed by size exclusion chromatography

• Structural Analysis:

  • Circular dichroism (CD) spectroscopy to assess secondary structure

  • Cryo-electron microscopy for tertiary/quaternary structure determination

  • X-ray crystallography following successful crystallization

  • NMR spectroscopy for dynamic structural information

• Functional Assays:

  • Liposome reconstitution to assess transport function

  • Patch-clamp techniques if channel activity is suspected

  • Substrate binding assays to identify potential ligands

  • Protein-protein interaction studies using pull-down assays or crosslinking

• Genetic Approaches:

  • Gene knockout studies to assess phenotypic effects

  • Complementation assays to confirm functional roles

  • Site-directed mutagenesis of conserved residues to identify functional domains

  • Reporter fusion constructs to study regulation and expression patterns

• Cellular Localization:

  • Fluorescent protein fusions for visualization

  • Immunolocalization using specific antibodies

  • Subcellular fractionation followed by Western blotting

The combination of these methodologies provides comprehensive insights into both the structural properties and functional roles of membrane proteins like yihY. For optimal results, initial characterization should focus on expression and purification optimization, followed by structural studies to inform functional investigations.

What is the relationship between Salmonella agona persistence in environmental settings and the expression of membrane proteins like yihY?

The persistence of Salmonella agona in environmental settings over extended periods presents a significant research challenge that may be linked to membrane protein expression patterns. Evidence from outbreak investigations shows that Salmonella agona can persist in food processing facilities for at least 10 years, as demonstrated by the linked cereal-associated outbreaks in 1998 and 2008 . This persistence capability likely involves complex adaptations that may include altered membrane protein expression.

Methodological approaches to investigate this relationship include:

• Transcriptomic Analysis:

  • RNA-seq comparison between persistent and laboratory strains

  • Quantitative PCR targeting yihY and related membrane protein genes

  • Transcriptional profiling under different environmental stressors

• Proteomics:

  • Comparative membrane proteome analysis between persistent and reference strains

  • Quantitative assessment of yihY protein levels under different environmental conditions

  • Post-translational modification analysis

• Functional Genomics:

  • Construction of yihY knockout strains to assess environmental persistence

  • Overexpression studies to determine if enhanced yihY levels confer survival advantages

  • Complementation studies in knockout strains

• Environmental Simulation Studies:

  • Controlled exposure to desiccation, nutrient limitation, and temperature fluctuation

  • Biofilm formation assays comparing wild-type and yihY mutant strains

  • Competition assays between persistent strains and laboratory reference strains

The limited genetic drift observed in persistent strains (mean of eight SNP differences over 10 years) suggests that the genes essential for environmental persistence, potentially including membrane proteins like yihY, are under strong selective pressure. Investigating differential expression of membrane proteins between persistent environmental isolates and non-persistent strains may reveal adaptation mechanisms that enable long-term survival in food processing environments.

How do genetic variations in the yihY gene correlate with Salmonella agona virulence and transmission potential?

The relationship between yihY genetic variations and Salmonella agona virulence represents an important research avenue for understanding pathogenicity mechanisms. A systematic approach to investigating this correlation requires:

• Comparative Genomic Analysis:

  • SNP identification across yihY sequences from multiple isolates

  • Correlation of specific variants with outbreak-associated strains

  • Identification of selection signatures in the yihY gene sequence

• Structure-Function Analysis:

  • Mapping of SNPs onto protein structural models

  • Assessment of whether variations occur in functional domains

  • Prediction of functional impacts using computational tools

• Experimental Validation:

  • Construction of isogenic strains differing only in yihY variants

  • Virulence assessment using cell invasion assays

  • Animal infection models comparing different yihY variants

• Transmission Studies:

  • Airborne transmission experiments using strains with different yihY variants

  • Assessment of environmental persistence capabilities

  • Evaluation of host colonization efficiency

The experimental airborne transmission studies of Salmonella Agona in pigs provide a methodological framework for such investigations . These studies demonstrated that Salmonella Agona could be transmitted via airborne routes, with recovery of the pathogen from air samples and sentinel animals. Extending this methodology to compare transmission efficiency between strains harboring different yihY variants could reveal whether specific genetic variations enhance transmission potential.

Similarly, the analysis of outbreak strains from 1998 and 2008 revealed limited genetic variation despite the 10-year interval , suggesting strong selection pressure on genes important for virulence and persistence. Detailed examination of whether the yihY gene was conserved or variable between these outbreak strains could provide insights into its role in pathogenicity.

What role might Salmonella agona UPF0761 membrane protein yihY play in antibiotic resistance mechanisms?

The potential contribution of membrane proteins like yihY to antibiotic resistance mechanisms represents a critical research question that requires systematic investigation. While direct evidence for yihY's role in antibiotic resistance is not provided in the available search results, several methodological approaches can address this question:

• Expression Analysis in Resistant Strains:

  • Comparative transcriptomics between susceptible and resistant isolates

  • qRT-PCR quantification of yihY expression following antibiotic exposure

  • Western blot analysis to assess protein levels in response to antibiotic pressure

• Genetic Manipulation Studies:

  • Generation of yihY knockout mutants and assessment of antibiotic susceptibility profiles

  • Complementation studies to confirm phenotypic changes

  • Overexpression experiments to determine if elevated yihY levels affect resistance

• Structural and Functional Characterization:

  • Investigation of potential antibiotic binding sites within the yihY protein

  • Assessment of membrane permeability in wild-type versus yihY mutant strains

  • Efflux assays to determine if yihY participates in antibiotic efflux mechanisms

• Clinical Isolate Analysis:

  • Sequencing of yihY from clinical isolates with different resistance profiles

  • Correlation analysis between yihY sequence variations and resistance patterns

  • Temporal studies to track yihY evolution in response to antibiotic selection pressure

As a membrane protein, yihY could potentially contribute to antibiotic resistance through several mechanisms: alteration of membrane permeability, participation in efflux systems, or modification of cell envelope properties that affect antibiotic penetration. The protein's predicted transmembrane topology suggests potential roles in membrane organization that could influence antibiotic susceptibility.