Recombinant Yersinia pestis bv. Antiqua UPF0259 membrane protein YPN_1667 (YPN_1667)

What is Yersinia pestis bv. Antiqua UPF0259 membrane protein YPN_1667?

YPN_1667 is a membrane protein from Yersinia pestis biovar Antiqua, belonging to the UPF0259 protein family. It consists of 256 amino acids with a sequence starting with MPITANTLYRDS and ending with LFRLYMLLRPVSLDKQ. The "UPF" designation (Uncharacterized Protein Family) indicates that its specific function has not been fully characterized yet. As a membrane protein, it likely plays a role in cellular processes involving the bacterial membrane, potentially including signaling, transport, or host-pathogen interactions .

How does Yersinia pestis bv. Antiqua relate to other Y. pestis biovars?

Yersinia pestis is commonly divided into three classical biovars: Antiqua, Medievalis, and Orientalis. All three belong to the subspecies pestis that is pathogenic to humans. There is also the non-human pathogenic biovar Microtus (alias Pestoides). Genotyping and phylogenetic analyses suggest that Y. pestis subspecies pestis emerged in the Central Asia region between China, Kazakhstan, Russia, and Mongolia . The differences between biovars are based on their biochemical properties and geographical distribution, with molecular typing methods enabling more precise classification and evolutionary studies.

What is the predicted structure and topology of YPN_1667?

Based on the amino acid sequence (MPITANTLYRDSFNFLRNQIAAILLLALLTAFITVMLNQTFMPASEQLSILSIPENDITS SGNLSISEIVSQMTPEQQMVLLRVSAVATFSALVGNVLLVGGLLTLIAMVSQGRRVSALQ AIGLSLPILPRLLVLMFISTLVIQLGLTFFIVPGVAIAIALSLSPIIVTNERMGIFAAMK ASAQLAFANVRLIVPAMMLWIAVKLLLLFLISRFTVLPPTIATIVLSTLSNLASALLLVY LFRLYMLLRPVSLDKQ), YPN_1667 is predicted to be an integral membrane protein with multiple transmembrane domains . The sequence contains several hydrophobic stretches typical of membrane-spanning α-helices. Without experimental structural data, prediction algorithms suggest it may contain multiple transmembrane domains with connecting loops of varying lengths. The protein's exact orientation in the membrane and the positioning of N and C termini require experimental verification.

What is the evolutionary significance of UPF0259 membrane proteins across Yersinia species?

The UPF0259 membrane protein family appears to be conserved across Yersinia species, suggesting important biological roles maintained through evolutionary pressure. Comparing YPN_1667 with homologs such as YPA_1558 in another Y. pestis strain reveals high sequence conservation . This conservation might indicate roles in essential cellular functions rather than virulence-specific activities, although experimental verification is needed. Phylogenetic analysis using multi-locus VNTR analysis (MLVA) and core genome multilocus sequence typing (cgMLST) could place YPN_1667 in an evolutionary context within the Yersinia genus . The Yersiniomics database facilitates such comparative genomic analyses across Yersinia species.

How might YPN_1667 potentially contribute to Y. pestis pathogenicity?

While the specific function of YPN_1667 remains uncharacterized, as a membrane protein in a highly pathogenic bacterium, it could potentially play roles in host-pathogen interactions, environmental sensing, or adaptation to different host environments. Membrane proteins often function as receptors, transporters, or components of secretion systems crucial for bacterial survival and virulence. To determine its potential role in pathogenicity, researchers should conduct gene knockout studies and assess changes in virulence in appropriate model systems. Comparative analyses with homologs in pathogenic and non-pathogenic Yersinia species could provide insights into whether YPN_1667 is associated with virulence-specific functions.

What experimental approaches are most effective for identifying interaction partners of YPN_1667?

Identifying interaction partners for membrane proteins like YPN_1667 requires specialized approaches that account for their hydrophobic nature and membrane environment. Effective methodologies include:

• Crosslinking-based approaches using membrane-permeable crosslinkers

• Proximity-dependent biotin labeling techniques (BioID, APEX)

• Split-system approaches modified for membrane proteins (split-ubiquitin yeast two-hybrid)

• Co-immunoprecipitation under detergent conditions that preserve native interactions

• Mass spectrometry-based interactomics with careful membrane extraction protocols

For each approach, appropriate controls must include:

• Non-specific binding controls (e.g., unrelated membrane protein of similar size)

• Detergent-specific controls to distinguish true interactors from detergent-sensitive artifacts

• Expression level controls to account for overexpression effects

The choice of method should be guided by the specific research question and available resources.

What are the optimal conditions for expressing and purifying recombinant YPN_1667?

For optimal expression and purification of recombinant YPN_1667, the following methodological approach is recommended:

Expression System and Conditions:

• Expression host: E. coli, as indicated in product information

• Culture temperature: Initially at 37°C until OD600 of 0.6-0.8, then reduce to 16-25°C for protein expression

• Induction: IPTG at 0.1-0.5 mM for membrane proteins

• Duration: 16-20 hours at reduced temperature

Purification Protocol:

• Cell lysis: French press or sonication in buffer containing protease inhibitors

• Membrane isolation: Ultracentrifugation (100,000 × g, 1 hour)

• Solubilization: Mild detergents such as DDM (n-Dodecyl β-D-maltoside) or LDAO

• Affinity purification: Using Ni-NTA resin to capture His-tagged protein

• Size exclusion chromatography: To remove aggregates and ensure homogeneity

Buffer Composition:

• Purification buffer: 50 mM Tris-HCl pH 8.0, 300 mM NaCl, 0.1% detergent, 5% glycerol

• Storage buffer: Tris/PBS-based buffer with 50% glycerol as recommended

Quality Control:

• SDS-PAGE: Should show >90% purity as specified

• Western blotting: Confirmation with anti-His antibodies

• Mass spectrometry: Verification of protein identity

How should researchers design mutagenesis studies to probe YPN_1667 function?

Strategic mutagenesis of YPN_1667 requires careful planning based on sequence analysis, evolutionary conservation, and structural predictions. A comprehensive approach would include:

Target Selection Strategy:

• Conserved residues across Yersinia species (potential functional hotspots)

• Predicted transmembrane segments vs. loop regions

• Charged or polar residues within transmembrane regions (often functionally significant)

• Potential post-translational modification sites

Mutation Types:

• Alanine scanning of consecutive segments

• Conservative substitutions (e.g., Leu→Ile, Asp→Glu)

• Charge reversals for electrostatic interactions

• Cysteine substitutions for accessibility studies and crosslinking

Experimental Design Table:

Readout Systems:

• Bacterial growth phenotypes under stress conditions

• Membrane localization via fractionation

• Protein-protein interaction studies with known partners

• In vivo virulence in appropriate model systems

What approaches are recommended for reconstituting YPN_1667 into membrane mimetics for functional studies?

Functional characterization of membrane proteins like YPN_1667 often requires reconstitution into appropriate membrane environments. Recommended approaches include:

Detergent Selection:

• Initial screening of multiple detergents (DDM, LDAO, Triton X-100)

• Stability assessment via thermal shift assays

• Functional retention tests in each detergent

Reconstitution Methods:

• Liposome Reconstitution:

  • Prepare liposomes with E. coli lipid extract or defined lipid mixtures

  • Detergent-mediated incorporation followed by detergent removal

  • Verification of orientation by protease protection assays

• Nanodiscs Assembly:

  • Co-assembly with MSP (membrane scaffold protein) and lipids

  • Size exclusion chromatography for homogeneity

  • Advantages include defined size and accessibility from both sides

• Amphipol Stabilization:

  • Replacing detergents with amphipathic polymers

  • Maintaining native-like environment with improved stability

  • Compatibility with various biophysical techniques

Functional Verification Methods:

• Circular dichroism to confirm secondary structure retention

• Fluorescence-based assays for conformational changes

• Activity assays based on hypothesized function (transport, signaling)

These approaches provide complementary environments for studying different aspects of YPN_1667 function while maintaining its native-like structural properties.

How should researchers design experiments to elucidate the function of YPN_1667?

Elucidating the function of an uncharacterized membrane protein like YPN_1667 requires a multi-faceted experimental approach:

Phase 1: Computational Analysis and Hypothesis Generation

• Sequence-based predictions of function using advanced bioinformatics tools

• Structural modeling to identify potential functional sites

• Genomic context analysis to identify functionally related genes

• Expression pattern analysis using Yersiniomics database data

Phase 2: Genetic Approaches

• Generate precise gene deletion mutant (ΔypnN_1667)

• Complementation strains with wild-type and mutant variants

• Phenotypic screening under diverse conditions:

  • Temperature variations (28°C, 37°C)

  • pH stress (acidic and alkaline)

  • Osmotic stress conditions

  • Antimicrobial peptide exposure

  • Host-relevant conditions

Phase 3: Biochemical Characterization

• Purification of recombinant protein (as detailed in section 3.1)

• Lipid binding assays

• Transport assays if channel/transporter function is suspected

• Binding studies with potential ligands identified from computational analysis

Phase 4: Structural Studies

• Limited proteolysis to identify domain boundaries

• Cryo-EM or X-ray crystallography attempts

• Site-directed spin labeling for EPR studies of dynamics

Phase 5: Host-Pathogen Interaction Studies

• Infection assays with wild-type vs. ΔypnN_1667 strains

• Host cell response transcriptomics

• Localization studies during infection

This systematic approach moves from in silico prediction to in vitro biochemistry to in vivo relevance, with each phase informing subsequent experiments.

What controls should be included when studying the effects of YPN_1667 deletion on Y. pestis virulence?

When investigating YPN_1667's role in virulence, rigorous experimental controls are essential:

Genetic Controls:

• Wild-type Y. pestis strain (positive control)

• Clean deletion mutant (ΔypnN_1667)

• Complemented strain (ΔypnN_1667 + ypnN_1667)

• Complemented strain with non-functional point mutant

• Deletion of unrelated membrane protein of similar size (specificity control)

Phenotypic Assessment Controls:

• Growth curve analysis under standard conditions

• Membrane integrity verification (permeability assays)

• Expression profiling of adjacent genes (RT-qPCR)

• Verification of protein absence by western blotting

Infection Model Controls:

• Dose standardization based on viable count, not optical density

• Mock infection controls

• Positive control with known virulence factor mutant

• Time course analysis (not just endpoint measurements)

Data Analysis Requirements:

• Minimum of three biological replicates

• Appropriate statistical tests with multiple comparison corrections

• Blinded assessment of outcomes where possible

• Verification in multiple infection models when possible

Using this control framework ensures that observed phenotypes are specifically attributable to YPN_1667 rather than experimental artifacts or polar effects on adjacent genes.

How can researchers design experiments to determine if YPN_1667 functions as a transporter or channel?

As a membrane protein, YPN_1667 might function as a transporter or channel. A systematic approach to test this hypothesis would include:

Substrate Prediction and Screening:

• In silico docking studies with metabolite libraries

• Sequence-based comparison with known transporters

• High-throughput screening against diverse compound libraries

Expression Systems for Functional Testing:

• Bacterial expression in transport-deficient strains

• Xenopus oocyte expression for electrophysiology

• Reconstitution into proteoliposomes for flux assays

Functional Assay Design:

• Radiolabeled substrate uptake/efflux measurements

• Fluorescence-based transport assays using substrate analogs

• Patch-clamp electrophysiology for channel function

• Liposome-based counterflow assays

Mechanistic Characterization:

• Substrate specificity profiling

• Kinetic measurements (Km, Vmax)

• Inhibitor screening and characterization

• Energy coupling determination (ATP-dependent, ion-coupled, facilitated diffusion)

Experimental Design Table:

How should researchers analyze sequence conservation patterns of YPN_1667 across Yersinia species?

Analyzing sequence conservation of YPN_1667 requires sophisticated approaches that account for membrane protein evolution patterns:

Sequence Collection and Alignment:

• Identify homologs across Yersinia species and related genera

• Use specialized alignment algorithms for membrane proteins (e.g., PRALINE-TM)

• Manually curate alignments, particularly for transmembrane regions

• Distinguish between pathogenic and non-pathogenic species homologs

Conservation Analysis Methods:

• Position-specific conservation scoring (using methods like ConSurf)

• Residue property conservation vs. exact residue conservation

• Transmembrane vs. loop region conservation patterns

• Coevolution analysis to identify functionally coupled residues

Visualization and Interpretation:

• Hydropathy plots overlaid with conservation scores

• Helical wheel projections for transmembrane segments

• Mapping conservation onto predicted 3D structures

• Correlation of conservation with predicted functional sites

Application to Experimental Design:

• Identification of candidate residues for mutagenesis

• Recognition of potential functional motifs

• Prediction of protein interfaces or binding sites

• Selection of regions for antibody generation

The available sequence data for YPN_1667 and related proteins like YPA_1558 provide starting points for these analyses, which can then guide hypothesis-driven experimental work.

What bioinformatic pipelines are recommended for predicting YPN_1667 structure and function?

For comprehensive structure-function prediction of YPN_1667, we recommend an integrated bioinformatic pipeline:

Structure Prediction Pipeline:

• Transmembrane Topology Analysis:

  • TMHMM, TOPCONS, and Phobius for initial predictions

  • Consensus building across multiple algorithms

  • Confidence assessment for each predicted segment

• Secondary Structure Prediction:

  • PSIPRED and JPred for general secondary structure

  • Specialized membrane protein predictors (OCTOPUS)

  • Identification of potential non-membrane structural elements

• Tertiary Structure Modeling:

  • Template identification using HHpred or Phyre2

  • AlphaFold2 for ab initio modeling

  • Refinement in explicit membrane environments

  • Quality assessment with ProQ3D or QMEANBrane

Function Prediction Pipeline:

• Domain and Motif Analysis:

  • InterProScan for domain identification

  • MEME for novel motif discovery

  • Comparison with membrane protein-specific motif databases

• Genomic Context Analysis:

  • Operon structure examination across Yersinia species

  • Gene neighborhood conservation

  • Co-evolution with potential functional partners

• Molecular Dynamics Simulations:

  • Structural stability assessment in membrane

  • Identification of potential binding pockets

  • Water/ion permeation pathways if channel function is suspected

• Integrative Scoring:

  • Combine evidence from multiple sources

  • Weighted prediction confidence scores

  • Prioritization of function hypotheses for experimental testing

The amino acid sequence of YPN_1667 (provided in search result ) should be processed through this pipeline to generate testable hypotheses about its structure and function.

How can transcriptomic data from the Yersiniomics database be leveraged to understand YPN_1667 function?

The Yersiniomics database, with its 317 transcriptomic datasets , provides valuable resources for understanding YPN_1667 function through expression pattern analysis:

Expression Correlation Analysis:

• Extract YPN_1667 expression profiles across all conditions

• Identify co-expressed genes using Pearson or Spearman correlation

• Perform hierarchical clustering to find expression modules

• Compare with known pathways and functional gene sets

Condition-Specific Expression Patterns:

• Identify conditions that significantly up/down-regulate YPN_1667

• Compare expression between pathogenic and non-pathogenic Yersinia

• Analyze temperature-dependent expression (host vs. environmental)

• Examine stress response patterns (acid, oxidative, antimicrobial)

Regulon Analysis:

• Identify potential transcription factor binding sites upstream of YPN_1667

• Compare with regulons of characterized transcription factors

• Build regulatory network models incorporating YPN_1667

Multi-omics Integration:

• Correlate transcriptomic data with available proteomic data

• Overlay expression data onto protein-protein interaction networks

• Integrate with metabolomic data if available to identify potential substrates

Application to Experimental Design:

By systematically analyzing expression patterns across diverse conditions, researchers can develop focused hypotheses about YPN_1667 function that can be experimentally tested.