Recombinant Staphylococcus aureus UPF0365 protein SAOUHSC_01676 (SAOUHSC_01676)

Are there any known functional domains in SAOUHSC_01676 protein?

While the SAOUHSC_01676 protein is classified as part of the UPF0365 family (Uncharacterized Protein Family), comparative analysis suggests potential functional associations. The protein is also annotated as FloA (Flotillin-like protein A) in some databases, indicating a possible role in membrane organization and signaling processes . Bioinformatic analysis reveals the presence of several putative functional regions:

• N-terminal transmembrane domain (residues 1-30)

• Potential oligomerization domains in the central region

• C-terminal region with charged residues suggesting interactions with other proteins

Advanced structural studies combining X-ray crystallography with molecular dynamics simulations would be necessary to fully characterize the functional domains of this protein .

How can I analyze the membrane localization properties of SAOUHSC_01676?

Analyzing the membrane localization of SAOUHSC_01676 requires a multi-faceted approach:

• Computational prediction: Begin with transmembrane prediction tools (TMHMM, Phobius) to identify potential membrane-spanning regions in the amino acid sequence (approximately residues 1-30).

• Subcellular fractionation: Isolate membrane fractions from S. aureus or expression systems through differential centrifugation, followed by Western blotting using antibodies against SAOUHSC_01676 or its tag.

• Fluorescence microscopy visualization: Create GFP fusion constructs and observe localization patterns in live cells. Comparison with known membrane markers can provide spatial resolution.

• Protease accessibility assays: Determine membrane topology by exposing intact cells vs. spheroplasts to proteases, followed by protein detection to establish which regions are protected.

For advanced analysis, incorporate FRAP (Fluorescence Recovery After Photobleaching) to measure protein mobility within the membrane, which provides insights into functional interactions and complex formation .

What expression systems are suitable for producing recombinant SAOUHSC_01676?

When working with membrane-associated proteins like SAOUHSC_01676, E. coli strains optimized for membrane protein expression (C41/C43) should be considered to improve folding and yield .

What purification strategy would you recommend for obtaining high-purity SAOUHSC_01676?

A robust purification strategy for SAOUHSC_01676 should address its membrane association properties while maximizing yield and purity. The following step-wise procedure is recommended:

• Expression optimization: Express the His-tagged protein in E. coli using auto-induction media at lower temperatures (16-18°C) to improve folding.

• Cell lysis and solubilization: Use mild detergents (DDM, LDAO) in the lysis buffer to solubilize the membrane-associated protein without denaturing it.

• Primary purification: Immobilized metal affinity chromatography (IMAC) using Ni-NTA resin with gradient elution (50-300 mM imidazole).

• Secondary purification: Size exclusion chromatography to separate monomeric protein from aggregates and remove residual contaminants.

• Quality control: Assess purity by SDS-PAGE (>90% purity standard) and verify identity through Western blotting and mass spectrometry.

For membrane protein studies, consider incorporating amphipols or nanodiscs during the purification process to maintain native-like environments and improve stability .

How can I troubleshoot low expression yields of SAOUHSC_01676?

When experiencing low expression yields of SAOUHSC_01676, implement a systematic troubleshooting approach:

• Codon optimization: Analyze the codon usage of the SAOUHSC_01676 gene in your expression system. S. aureus has a different codon bias compared to E. coli, which may affect translation efficiency. Consider synthesizing a codon-optimized gene for your expression host.

• Expression conditions matrix:

  • Test multiple induction temperatures (18°C, 25°C, 30°C, 37°C)

  • Vary inducer concentrations (0.1 mM - 1.0 mM IPTG or equivalent)

  • Adjust induction timing (early-log to mid-log phase)

  • Test different media formulations (LB, TB, auto-induction)

• Fusion tag screening: If the standard His-tag approach yields poor results, screen alternative fusion partners:

  • Solubility enhancers (MBP, SUMO, TRX)

  • Alternative affinity tags (GST, FLAG, Strep)

• Host strain evaluation: Test specialized E. coli strains:

  • BL21(DE3)pLysS for toxic protein control

  • Rosetta for rare codon supplementation

  • C41/C43 for membrane protein expression

• Protein stability assessment: Add protease inhibitors throughout the process and analyze samples from multiple timepoints to identify potential degradation issues .

What is known about the functional role of SAOUHSC_01676 in Staphylococcus aureus?

The SAOUHSC_01676 protein, also known as FloA (Flotillin-like protein A), is believed to play roles in membrane organization and potentially in bacterial virulence, though detailed characterization remains limited. Based on homology studies and preliminary functional analyses:

• Membrane microdomain organization: Like eukaryotic flotillins, SAOUHSC_01676 likely participates in organizing functional membrane microdomains that serve as platforms for protein complexes.

• Signal transduction: There is evidence suggesting association with two-component systems such as SaeRS, which regulates virulence factor expression in S. aureus. This relationship indicates potential involvement in sensing environmental signals and transducing them into cellular responses .

• Biofilm formation: Preliminary studies indicate potential roles in biofilm development and maintenance, possibly through influencing cell-cell adhesion and extracellular matrix interactions.

• Stress response: Expression patterns suggest upregulation during certain stress conditions, indicating potential roles in adaptive responses to environmental challenges.

Further functional characterization through gene deletion, complementation studies, and protein interaction analyses would provide deeper insights into its physiological role .

How does SAOUHSC_01676 interact with the SaeRS two-component system?

The interaction between SAOUHSC_01676 and the SaeRS two-component system represents an intriguing area of research with implications for S. aureus virulence regulation. Though not fully characterized, several methodological approaches can elucidate this relationship:

• Co-immunoprecipitation (Co-IP): Using antibodies against SAOUHSC_01676 or SaeRS components (SaeR/SaeS) to pull down protein complexes, followed by Western blotting or mass spectrometry to identify interacting partners.

• Bacterial two-hybrid assays: Employing split-reporter systems to detect direct protein-protein interactions between SAOUHSC_01676 and SaeR or SaeS in vivo.

• Fluorescence microscopy co-localization: Creating fluorescently tagged versions of both proteins to visualize their spatial relationship within bacterial cells under various conditions.

• Transcriptional reporter assays: Measuring the activity of SaeRS-dependent promoters (such as Phla) in wildtype versus SAOUHSC_01676 deletion mutants to assess functional impact.

Current data suggests that SAOUHSC_01676 may influence SaeRS activity by:

• Facilitating the localization of SaeS within the membrane

• Modulating the interaction between SaeS and SaeR

• Affecting the phosphorylation state of SaeR, particularly in response to zinc availability and calprotectin sensing .

What experimental approaches can determine if SAOUHSC_01676 influences bacterial virulence?

To investigate the potential role of SAOUHSC_01676 in S. aureus virulence, a comprehensive experimental framework combining molecular, cellular, and in vivo approaches is recommended:

• Genetic manipulation studies:

  • Create clean gene deletion mutants (ΔSAOUHSC_01676)

  • Develop complementation strains with controlled expression

  • Engineer point mutations in key functional domains

  • Construct reporter fusions to monitor expression patterns

• Virulence factor assessment:

  • Quantify hemolysis, coagulase, and protease activities

  • Measure toxin production using ELISA or Western blotting

  • Analyze secretome differences using proteomics

  • Monitor expression of virulence genes using qRT-PCR

• Infection models:

  • Cell culture invasion and persistence assays

  • Whole blood survival tests

  • Invertebrate infection models (Galleria mellonella)

  • Mammalian infection models (murine abscess, sepsis)

• Host-pathogen interaction studies:

  • Neutrophil killing resistance

  • Macrophage intracellular survival

  • Complement resistance assays

  • Immune cell activation measurements

• Mechanistic investigations:

  • Examine impacts on SaeRS signaling pathways

  • Assess membrane domain organization

  • Analyze protein interaction networks

  • Evaluate structural changes during infection conditions

What are the optimal storage conditions for maintaining SAOUHSC_01676 stability?

The optimal storage conditions for maintaining SAOUHSC_01676 stability are critical for preserving protein activity and structural integrity. According to product specifications:

• Long-term storage: Store the lyophilized protein at -20°C to -80°C. The lower temperature (-80°C) is preferable for extended storage periods (>6 months) .

• Working aliquots: Store reconstituted protein aliquots at 4°C for up to one week. Avoid repeated freeze-thaw cycles as they significantly reduce protein stability and activity .

• Buffer composition: The recommended storage buffer consists of Tris/PBS-based buffer with 6% Trehalose at pH 8.0. For reconstituted protein, adding glycerol to a final concentration of 50% helps maintain stability during freeze-thaw transitions .

• Reconstitution protocol:

  • Centrifuge the vial briefly before opening

  • Reconstitute in deionized sterile water to 0.1-1.0 mg/mL

  • Add glycerol (5-50% final concentration) for cryoprotection

  • Prepare single-use aliquots to avoid repeated freeze-thaw cycles

For projects requiring prolonged use, stability can be further enhanced by adding reducing agents (1-5 mM DTT) or protease inhibitors to prevent oxidation and degradation.

How can I monitor the structural integrity of SAOUHSC_01676 after purification and storage?

Monitoring the structural integrity of SAOUHSC_01676 after purification and storage is essential to ensure experimental reproducibility. A multi-technique approach provides comprehensive assessment:

• SDS-PAGE and Western blotting:

  • Immediately after purification (baseline)

  • After various storage periods

  • Compare band patterns to detect degradation

  • Look for shifts in molecular weight or additional bands

• Circular Dichroism (CD) spectroscopy:

  • Measure secondary structure content

  • Compare fresh vs. stored samples for conformational changes

  • Monitor thermal stability through melting curves

• Size Exclusion Chromatography (SEC):

  • Assess aggregation state and oligomerization

  • Monitor shifts in elution profiles after storage

  • Quantify monomer to aggregate ratios

• Dynamic Light Scattering (DLS):

  • Measure particle size distribution

  • Track changes indicating aggregation

  • Monitor polydispersity as a quality indicator

• Functional activity assays:

  • Develop binding assays to known interactors

  • Compare activity between fresh and stored samples

  • Establish minimum activity thresholds for experimental use

Performing these analyses at regular intervals (freshly prepared, 1 week, 1 month, 3 months) provides valuable stability data to optimize storage conditions for specific experimental requirements .

How can SAOUHSC_01676 be utilized in studies of bacterial membrane organization?

SAOUHSC_01676 (FloA) presents a valuable tool for investigating bacterial membrane organization, particularly the formation and function of membrane microdomains in S. aureus. Researchers can implement several approaches:

• Fluorescent protein fusions:

  • Create N- or C-terminal fusions with fluorescent proteins (GFP, mCherry)

  • Visualize distribution patterns using super-resolution microscopy (STORM, PALM)

  • Perform time-lapse imaging to track dynamic reorganization under different conditions

• Membrane proteomics:

  • Use SAOUHSC_01676 as a bait protein in proximity labeling experiments (BioID, APEX)

  • Identify co-localizing proteins through quantitative proteomics

  • Map the composition of SAOUHSC_01676-associated membrane domains

• Lipid interaction studies:

  • Analyze lipid preferences through lipidomics of isolated membrane fractions

  • Reconstitute purified protein in model membranes with defined compositions

  • Examine effects on membrane fluidity and organization using fluorescent probes

• Bacterial two-component system interactions:

  • Investigate how SAOUHSC_01676 affects the localization and function of SaeRS components

  • Map the spatiotemporal dynamics of signal transduction in relation to membrane domains

  • Assess the impact on downstream gene expression using reporter constructs

These approaches can reveal fundamental principles of bacterial membrane organization and provide insights into potential targets for antimicrobial development.

What are the considerations for developing antibodies against SAOUHSC_01676?

Developing effective antibodies against SAOUHSC_01676 requires careful consideration of several factors to ensure specificity, sensitivity, and experimental utility:

• Antigen design strategies:

  • Full-length protein: Provides comprehensive epitope coverage but may present solubility challenges

  • Peptide-based: Select unique, surface-exposed regions (typically 15-20 amino acids)

  • Domain-specific: Target conserved functional domains for cross-species reactivity

• Immunization considerations:

  • Animal selection: Rabbits typically provide high-affinity polyclonal responses

  • Adjuvant selection: Balance immunogenicity with minimal non-specific stimulation

  • Immunization schedule: Primary plus 3-4 boosters over 2-3 months

• Antibody validation matrix:

• Special considerations for membrane proteins:

  • Use native conformation-preserving detergents during immunization

  • Consider whole-cell immunization for surface-exposed epitopes

  • Develop antibodies against both extracellular and intracellular domains

Purified recombinant His-tagged SAOUHSC_01676 (>90% purity) serves as an excellent immunogen and can also be used for antibody purification through affinity chromatography .

How can we investigate the role of SAOUHSC_01676 in antibiotic resistance mechanisms?

Investigating potential connections between SAOUHSC_01676 and antibiotic resistance mechanisms requires a systematic research approach:

• Comparative expression analysis:

  • Measure SAOUHSC_01676 expression levels in susceptible vs. resistant S. aureus strains

  • Monitor expression changes following sub-inhibitory antibiotic exposure

  • Perform RNA-seq to identify co-regulated genes in resistance pathways

• Genetic manipulation experiments:

  • Create SAOUHSC_01676 deletion and overexpression strains

  • Determine minimum inhibitory concentrations (MICs) for various antibiotics

  • Assess changes in resistance acquisition rates under selective pressure

• Membrane permeability studies:

  • Measure uptake of fluorescent dyes (propidium iodide, ethidium bromide)

  • Quantify antibiotic accumulation in wildtype vs. mutant strains

  • Analyze membrane fluidity and rigidity parameters

• Protein interaction investigations:

  • Identify interactions with known resistance determinants (PBPs, efflux pumps)

  • Examine co-localization with antibiotic targets using fluorescence microscopy

  • Perform pull-down assays to isolate SAOUHSC_01676-associated protein complexes

• In vivo infection models:

  • Compare treatment efficacy in infections with wildtype vs. mutant strains

  • Assess bacterial persistence following antibiotic treatment

  • Monitor resistance development during therapeutic regimens

This multi-faceted approach can reveal whether SAOUHSC_01676's membrane organization functions contribute to intrinsic or acquired resistance mechanisms in S. aureus .

How might SAOUHSC_01676 be involved in biofilm formation and persistence?

Investigating SAOUHSC_01676's role in biofilm formation and persistence requires a comprehensive experimental approach:

• Biofilm formation assessment:

  • Compare wildtype, deletion, and complemented strains using crystal violet assays

  • Analyze biofilm structure through confocal microscopy and 3D reconstruction

  • Measure extracellular matrix production (polysaccharides, eDNA, proteins)

  • Evaluate cell-cell adhesion properties and surface attachment capabilities

• Environmental response studies:

  • Examine biofilm development under different stressors (antibiotics, pH, osmolarity)

  • Monitor SAOUHSC_01676 expression throughout biofilm maturation using reporter fusions

  • Assess protein localization patterns in planktonic versus biofilm states

• Molecular mechanism investigations:

  • Analyze interaction with known biofilm regulators (SarA, Agr, Sae)

  • Identify changes in gene expression profiles between wildtype and mutant biofilms

  • Investigate co-localization with adhesins and other surface proteins

• Persistence and dispersal dynamics:

  • Evaluate susceptibility of mature biofilms to antimicrobial challenges

  • Measure persistence rates following antibiotic treatment

  • Analyze dispersal mechanisms and the role of SAOUHSC_01676 in this process

Current hypotheses suggest SAOUHSC_01676 may influence biofilm development through:

• Organization of membrane microdomains that coordinate adhesin presentation

• Modulation of two-component system signaling that regulates biofilm-associated genes

• Facilitation of cell-cell communication through membrane organization

• Coordination of stress responses that promote biofilm persistence

What experimental design would best elucidate the structure-function relationship of SAOUHSC_01676?

To comprehensively characterize the structure-function relationship of SAOUHSC_01676, a multi-disciplinary experimental design is optimal:

• High-resolution structural determination:

  • X-ray crystallography of purified protein (challenging for membrane proteins)

  • Cryo-electron microscopy to visualize membrane-associated conformations

  • NMR spectroscopy for dynamic regions and ligand interactions

  • Molecular dynamics simulations to model membrane integration

• Domain mapping through targeted mutagenesis:

  • Alanine-scanning mutagenesis of conserved residues

  • Domain deletion/swap experiments with related proteins

  • Site-directed mutagenesis of predicted functional motifs

  • Creation of chimeric proteins to identify specificity determinants

  Proposed Mutant Library:

  Mutation Type	Target Region	Expected Impact	Validation Assays
  Transmembrane disruption	Residues 1-30	Altered membrane localization	Microscopy, fractionation
  Oligomerization interface	Central region	Defective complex formation	SEC-MALS, native PAGE
  C-terminal truncations	Residues 280-329	Impaired protein interactions	Pull-down, Y2H
  Conserved motif mutations	Various	Function-specific defects	Reporter assays, phenotyping

• Structure-guided functional assays:

  • Membrane localization studies with fluorescent protein fusions

  • Protein interaction analyses with predicted partners

  • Assessment of oligomerization states under various conditions

  • Correlation of structural features with phenotypic outcomes

• Comparative analysis across species:

  • Identify conservation patterns in UPF0365 family proteins

  • Perform complementation studies with homologs from other bacteria

  • Map species-specific versus conserved functional elements

This integrated approach would connect structural features to specific cellular functions and provide mechanistic insights into SAOUHSC_01676's role in S. aureus biology .

How can systems biology approaches integrate SAOUHSC_01676 into broader S. aureus regulatory networks?

Systems biology approaches offer powerful frameworks to contextualize SAOUHSC_01676 within the complex regulatory landscape of S. aureus:

• Multi-omics integration:

  • Transcriptomics: RNA-seq comparing wildtype vs. SAOUHSC_01676 mutants under various conditions

  • Proteomics: Quantitative analysis of protein abundance changes and post-translational modifications

  • Metabolomics: Identification of metabolic pathway alterations resulting from SAOUHSC_01676 disruption

  • Interactomics: Comprehensive protein interaction mapping using AP-MS or BioID approaches

• Network reconstruction and analysis:

  • Generate protein-protein interaction networks centered on SAOUHSC_01676

  • Construct regulatory networks incorporating transcription factors and two-component systems

  • Develop predictive models of information flow through these networks

  • Identify network motifs and regulatory hubs connected to SAOUHSC_01676

• Perturbation studies:

  • Systematic combinatorial gene deletions with SAOUHSC_01676 and potential interactors

  • Chemical genomics screens to identify synthetic interactions

  • Environmental stress response profiling across genetic backgrounds

  • Time-resolved analyses of network dynamics following stimulation

• Computational modeling:

  • Develop ordinary differential equation models of SAOUHSC_01676-influenced pathways

  • Perform constraint-based modeling to predict metabolic impacts

  • Implement machine learning approaches to identify emergent patterns

  • Create predictive models of virulence and antibiotic resistance based on network states

These approaches would position SAOUHSC_01676 within the broader context of S. aureus biology, potentially revealing unexpected connections to virulence regulation, stress responses, and bacterial adaptation mechanisms .

What are the most promising research directions for understanding SAOUHSC_01676 function?

Based on current knowledge and technological capabilities, several research directions show particular promise for elucidating SAOUHSC_01676 function:

• Structural biology approaches: High-resolution structures through cryo-EM or X-ray crystallography would provide crucial insights into how this protein organizes within the membrane and interacts with partners. These structural details could inform targeted mutagenesis studies to dissect specific functional domains.

• Membrane microdomain characterization: Advanced imaging techniques like super-resolution microscopy combined with specific lipid probes could reveal how SAOUHSC_01676 organizes membrane domains in S. aureus. These studies would benefit from correlative light and electron microscopy approaches to connect protein localization with membrane ultrastructure.

• Interactome mapping: Comprehensive identification of SAOUHSC_01676 protein interaction networks across different environmental conditions would place this protein within cellular pathways. Techniques like BioID, proximity labeling, or cross-linking mass spectrometry offer promising approaches for capturing both stable and transient interactions.

• In vivo infection models: Evaluating the contribution of SAOUHSC_01676 to S. aureus pathogenesis in relevant animal models would connect molecular mechanisms to disease outcomes. These studies should incorporate tissue-specific analyses and immune response measurements.

• Two-component system integration: Detailed investigation of how SAOUHSC_01676 interfaces with the SaeRS and other two-component systems would reveal its role in signal transduction networks that control virulence and adaptation .

How might research on SAOUHSC_01676 contribute to new antimicrobial strategies?

Research on SAOUHSC_01676 could potentially inform novel antimicrobial strategies through several mechanisms:

• Membrane organization disruption: If SAOUHSC_01676 plays a critical role in organizing functional membrane microdomains, compounds that disrupt this organization could compromise bacterial survival or virulence. Small molecules targeting protein-lipid or protein-protein interactions involved in microdomain assembly represent a novel class of antimicrobial agents.

• Virulence attenuation: Rather than killing bacteria directly, targeting SAOUHSC_01676 could potentially attenuate virulence by disrupting regulatory networks that control toxin production and immune evasion mechanisms. This approach might reduce selection pressure for resistance compared to conventional antibiotics.

• Combination therapy enhancement: Inhibitors targeting SAOUHSC_01676 might sensitize S. aureus to existing antibiotics by altering membrane permeability or efflux pump organization. Identifying such synergistic interactions could revitalize currently ineffective antimicrobials.

• Biofilm prevention and disruption: If SAOUHSC_01676 contributes to biofilm formation or maintenance, targeting this protein could enhance biofilm penetration by antibiotics or directly prevent the establishment of these resistant communities.

• Diagnostic and monitoring applications: Understanding SAOUHSC_01676 expression patterns during infection could enable the development of diagnostic tools that predict antibiotic response or disease progression.

To advance these possibilities, high-throughput screening for inhibitors combined with detailed mechanism-of-action studies would be essential to translate basic research findings into therapeutic applications .

What are the technical challenges in studying SAOUHSC_01676 and how might they be overcome?

Studying SAOUHSC_01676 presents several technical challenges common to membrane protein research, along with specific difficulties related to S. aureus biology:

• Membrane protein solubility and stability:

  • Challenge: Maintaining native conformation during extraction and purification

  • Solutions:

    • Employ gentle detergents (DDM, LMNG) or styrene-maleic acid copolymers (SMAs)

    • Utilize nanodiscs or amphipols to provide membrane-like environments

    • Develop on-membrane structural analysis techniques like solid-state NMR

• S. aureus genetic manipulation:

  • Challenge: Lower transformation efficiency and homologous recombination rates

  • Solutions:

    • Optimize electroporation protocols with glycine treatment and wall-weakening agents

    • Employ CRISPR-Cas9 systems adapted for S. aureus

    • Utilize temperature-sensitive plasmids for chromosomal integration

• Functional redundancy:

  • Challenge: Potential compensation by related proteins masking phenotypes

  • Solutions:

    • Generate multiple deletion strains targeting related proteins

    • Employ inducible degradation systems for acute protein depletion

    • Utilize quantitative approaches sensitive to subtle phenotypic changes

• Complex membrane microdomain visualization:

  • Challenge: Resolution limitations in bacteria due to small size

  • Solutions:

    • Apply expansion microscopy techniques to increase effective resolution

    • Utilize correlative light and electron microscopy approaches

    • Develop proximity labeling methods specific for membrane domains

• Translation to in vivo relevance:

  • Challenge: Connecting molecular mechanisms to infection outcomes

  • Solutions:

    • Develop tissue-specific infection models

    • Employ dual RNA-seq to capture host-pathogen interactions

    • Create reporter strains for in vivo imaging of protein activity