Recombinant Pseudomonas aeruginosa UPF0060 membrane protein PLES_17921 (PLES_17921)

What is the structural composition of Recombinant Pseudomonas aeruginosa UPF0060 membrane protein PLES_17921?

Recombinant Pseudomonas aeruginosa UPF0060 membrane protein PLES_17921 (UniProt ID: B7V7I2) is a 109-amino acid protein with the following sequence: MINYFWFVLAAFCEIAGCYAFYLWLRLGKSALWVLPGLLSLTLFALLLTRVEASYAGRAY AAYGGIYVAASLFWLAFVERSRPLWSDWLGVALCVVGASVVLFGPRLSQ . The protein belongs to the UPF0060 family of membrane proteins and contains hydrophobic regions characteristic of proteins embedded in cell membranes. Structural analysis suggests it contains multiple transmembrane domains that anchor it within the bacterial membrane, with certain regions extending into either the cytoplasm or extracellular space.

What expression systems are most effective for producing Recombinant PLES_17921 protein?

The most documented and effective expression system for Recombinant PLES_17921 is E. coli, which has been successfully used to produce the His-tagged version of the protein . For membrane proteins like PLES_17921, expression optimization typically involves testing various E. coli strains (BL21(DE3), C41(DE3), C43(DE3)) that are engineered to accommodate membrane protein expression. Alternative expression systems including yeast, baculovirus, and mammalian cell systems may also be considered for specific research applications requiring different post-translational modifications or folding environments . Methodologically, researchers should compare protein yields, solubility, and functional integrity across different expression systems to determine the most suitable approach for their specific experimental needs.

How should researchers store and handle PLES_17921 protein to maintain stability?

For optimal stability of Recombinant PLES_17921 protein, storage at -20°C/-80°C is recommended for long-term preservation . The protein is typically supplied as a lyophilized powder in a Tris/PBS-based buffer containing 6% trehalose at pH 8.0 . For reconstitution, researchers should:

• Briefly centrifuge the vial before opening to bring contents to the bottom

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

• Add glycerol to a final concentration of 50% for long-term storage

• Aliquot the solution to minimize freeze-thaw cycles

Working aliquots can be maintained at 4°C for up to one week, but repeated freeze-thaw cycles should be avoided as they compromise protein integrity . For proteins used in functional assays, activity testing before and after storage periods is recommended to verify retention of biological function.

What are the optimal experimental designs for studying PLES_17921 function in Pseudomonas aeruginosa?

When designing experiments to study PLES_17921 function, researchers should consider both in vitro and in vivo approaches. A comprehensive experimental design should include the following elements:

• Independent and dependent variables: The independent variable might be the expression level of PLES_17921, while dependent variables could include membrane integrity, antibiotic resistance profiles, or virulence factors .

• Control groups: Include both positive controls (known membrane proteins with similar structure) and negative controls (membrane protein knockout strains or inactive protein variants) .

• Experimental approach selection:

  • Gene knockout/knockdown studies: CRISPR-Cas9 or antisense RNA approaches to reduce PLES_17921 expression and observe phenotypic changes

  • Protein localization: Fluorescent tagging (ensuring tags don't disrupt function) or immunohistochemistry to determine precise membrane localization

  • Protein-protein interaction studies: Pull-down assays, yeast two-hybrid, or co-immunoprecipitation to identify interaction partners

The experimental design should follow either repeated measures (testing multiple conditions on the same bacterial populations) or independent measures (different bacterial populations for each condition) depending on the specific research question .

How can researchers effectively design a study to evaluate PLES_17921 involvement in antibiotic resistance mechanisms?

To design a robust study evaluating PLES_17921's potential role in antibiotic resistance mechanisms, researchers should follow this methodological framework:

• Formulate a specific research question: "Does PLES_17921 contribute to specific antibiotic resistance mechanisms in Pseudomonas aeruginosa LESB58 strain?"

• Define experimental variables:

  • Independent variable: PLES_17921 expression levels (wild-type, overexpression, and knockout/knockdown)

  • Dependent variables: Minimum inhibitory concentrations (MICs) of various antibiotic classes, membrane permeability measurements, efflux pump activity

  • Control variables: Growth conditions, bacterial density, antibiotic exposure time

• Implement comparative experimental design:

  • Create isogenic strains differing only in PLES_17921 expression

  • Subject strains to antibiotic susceptibility testing using standardized methods (broth microdilution)

  • Measure membrane permeability using fluorescent dyes (e.g., propidium iodide, NPN)

  • Quantify expression of known resistance genes via RT-qPCR to identify potential regulatory relationships

• Data analysis plan:

  • Statistical comparison of MICs across strains (ANOVA or t-tests depending on distribution)

  • Correlation analysis between PLES_17921 expression and resistance phenotypes

  • Time-kill kinetics to evaluate dynamic response to antibiotics

This methodological approach allows for a systematic evaluation of PLES_17921's role while controlling for confounding variables that might affect antibiotic resistance phenotypes .

What purification methods are most effective for isolating PLES_17921 with high purity for structural studies?

For structural studies of membrane proteins like PLES_17921, obtaining high-purity preparations requires specialized approaches:

• Initial extraction from expression system:

  • For His-tagged PLES_17921, begin with immobilized metal affinity chromatography (IMAC) using Ni-NTA columns

  • Use appropriate detergents (DDM, LDAO, or OG) for solubilization from membranes without denaturing the protein

  • Include protease inhibitors throughout the purification process

• Secondary purification:

  • Size exclusion chromatography to remove aggregates and separate monomeric protein

  • Ion exchange chromatography for removing contaminants with different charge properties

• Quality control measures:

  • SDS-PAGE analysis to confirm >90% purity as documented for commercial preparations

  • Western blotting to verify protein identity

  • Dynamic light scattering to assess monodispersity

  • Circular dichroism to verify secondary structure integrity

• Optimization for structural studies:

  • Screen different detergent conditions for stability

  • Consider using lipid nanodiscs or amphipols for maintaining native-like environment

  • Evaluate protein stability using thermal shift assays before proceeding to structural determination methods

This purification workflow should yield protein preparations suitable for structural determination via X-ray crystallography, cryo-EM, or NMR spectroscopy, depending on the research objectives.

How can researchers investigate the functional relationship between PLES_17921 and Pseudomonas aeruginosa virulence mechanisms?

Investigating the relationship between PLES_17921 and virulence requires a multifaceted experimental approach:

• Gene expression correlation analysis:

  • Perform RNA-seq or microarray analysis comparing wild-type and PLES_17921-deficient strains under virulence-inducing conditions

  • Identify co-regulated genes that may participate in the same virulence pathways

  • Validate key findings using RT-qPCR for specific virulence factors

• Infection model studies:

  • Utilize both cell culture (e.g., lung epithelial cells) and animal models

  • Compare infection progression between wild-type and PLES_17921-modified strains

  • Measure specific virulence outcomes: biofilm formation, tissue invasion, immune response evasion

• Secretion system analysis:

  • Assess whether PLES_17921 affects the function of type III or type VI secretion systems

  • Quantify secreted virulence factors using proteomics approaches

  • Perform secretion assays using reporter proteins to measure efficiency

• Biofilm formation quantification:

  • Crystal violet staining for total biofilm biomass

  • Confocal microscopy with live/dead staining to assess biofilm architecture

  • Antibiotic penetration assays to determine if PLES_17921 affects biofilm permeability

This comprehensive approach allows researchers to determine if PLES_17921 directly contributes to virulence or indirectly affects virulence mechanisms through membrane structure alterations or regulatory pathways.

What techniques are available for studying the membrane topology and orientation of PLES_17921?

To elucidate the membrane topology and orientation of PLES_17921, researchers can employ these advanced methodological approaches:

• Computational prediction combined with experimental validation:

  • Use topology prediction algorithms (TMHMM, Phobius, MEMSAT) to generate initial models

  • Design experiments to specifically test these predictions

• Reporter fusion approaches:

  • PhoA (alkaline phosphatase) fusions: Active only when located in the periplasm

  • GFP fusions: Fluorescent only when located in the cytoplasm

  • Create a series of truncated PLES_17921 constructs with reporters to map transmembrane regions

• Cysteine scanning mutagenesis:

  • Introduce single cysteine residues at various positions

  • Test accessibility with membrane-impermeable sulfhydryl reagents

  • Positions accessible to external reagents indicate exposed regions

• Protease protection assays:

  • Treat membrane vesicles with proteases

  • Analyze protease-protected fragments

  • Identify domains protected by the membrane barrier

• Cryo-electron microscopy:

  • Purify protein in lipid nanodiscs or detergent micelles

  • Determine 3D structure at near-atomic resolution

  • Map orientation within the membrane mimetic

Each technique provides complementary information, and combining multiple approaches provides the most reliable topology model of this membrane protein.

How can researchers investigate potential protein-protein interactions involving PLES_17921 in the bacterial membrane?

To comprehensively investigate protein-protein interactions involving PLES_17921, researchers should implement a multi-technique strategy:

• In vivo crosslinking coupled with mass spectrometry:

  • Treat intact cells with membrane-permeable crosslinkers (DSP, formaldehyde)

  • Purify PLES_17921 under denaturing conditions to maintain crosslinks

  • Identify crosslinked partners using mass spectrometry

  • Validate with reciprocal pulldowns of identified partners

• Bacterial two-hybrid systems:

  • Adapt split adenylate cyclase or split ubiquitin systems for membrane protein interactions

  • Screen genomic libraries to identify novel interaction partners

  • Confirm specific interactions with targeted constructs

• Co-immunoprecipitation with membrane solubilization:

  • Optimize detergent conditions to solubilize PLES_17921 while maintaining protein-protein interactions

  • Use antibodies against tags (His-tag) or against PLES_17921 directly

  • Identify co-precipitating proteins by western blotting or mass spectrometry

• Proximity labeling approaches:

  • Express PLES_17921 fused to BioID or APEX2 enzymes

  • These enzymes biotinylate proteins in close proximity

  • Purify biotinylated proteins and identify by mass spectrometry

• FRET/BRET analysis for specific interactions:

  • Generate fluorescent or bioluminescent protein fusions

  • Measure energy transfer between PLES_17921 and putative partners

  • Quantify interaction strength under different conditions

This methodological framework provides multiple lines of evidence for protein interactions while addressing the challenges specific to membrane protein research.

How can researchers address solubility challenges when working with recombinant PLES_17921?

Membrane proteins like PLES_17921 present significant solubility challenges. Researchers can implement these methodological solutions:

• Optimized expression conditions:

  • Test multiple E. coli strains specifically designed for membrane proteins (C41, C43)

  • Reduce expression temperature (16-20°C) to slow protein production

  • Use weaker promoters or lower inducer concentrations

  • Consider auto-induction media for gradual protein expression

• Detergent screening and optimization:

  • Implement systematic detergent screens (starting with DDM, LDAO, OG)

  • Test detergent combinations for improved solubilization

  • Optimize detergent:protein ratios using small-scale extractions

  • Consider fluorescence-based thermal stability assays to identify stabilizing conditions

• Fusion protein approaches:

  • Beyond His-tags, test solubility-enhancing fusion partners (MBP, SUMO, Trx)

  • Position tags at either N- or C-terminus to determine optimal configuration

  • Include cleavable linkers if the fusion partner interferes with function

• Sample preparation protocol modifications:

  • For reconstituting lyophilized PLES_17921, follow the recommended procedure of rehydration in deionized sterile water to 0.1-1.0 mg/mL

  • Add glycerol (30-50%) to prevent aggregation during storage

  • Consider addition of specific lipids that may stabilize the native structure

• Troubleshooting aggregation:

  • Centrifuge samples (100,000×g) to remove aggregates before experiments

  • Filter through 0.22 μm filters to remove large particles

  • Use dynamic light scattering to monitor aggregation state

These systematic approaches address the inherent challenges of membrane protein solubility while maintaining the structural integrity necessary for functional studies.

What strategies should researchers employ when facing inconsistent results in PLES_17921 functional studies?

When encountering inconsistent results in PLES_17921 functional studies, researchers should implement this systematic troubleshooting framework:

• Protein quality assessment:

  • Verify protein integrity by SDS-PAGE and western blotting before each experimental series

  • Check for degradation products that might interfere with function

  • Confirm proper folding using circular dichroism or fluorescence spectroscopy

  • Ensure >90% purity as specified for research-grade preparations

• Experimental condition standardization:

  • Develop detailed standard operating procedures (SOPs) for all assays

  • Control for environmental variables (temperature, pH, buffer composition)

  • Utilize internal controls in each experiment for normalization

  • Standardize protein:lipid or protein:detergent ratios across experiments

• Technical variability reduction:

  • Implement technical replicates (minimum triplicate) for all measurements

  • Use automated liquid handling where possible to improve precision

  • Calibrate instruments regularly and document calibration

  • Consider blinded analysis to reduce experimental bias

• Statistical approach refinement:

  • Perform power analysis to ensure adequate sample sizes

  • Apply appropriate statistical tests based on data distribution

  • Consider hierarchical statistical models to account for batch effects

  • Implement more stringent significance thresholds for exploratory studies

• Systematic validation:

  • Reproduce key findings using alternative methodologies

  • Test in different strain backgrounds to ensure generalizability

  • Validate in physiologically relevant conditions

  • Compare results with published data on related membrane proteins

This methodological framework helps identify sources of variability and establishes whether inconsistencies arise from technical issues or reflect genuine biological complexity of PLES_17921 function.

How can researchers differentiate between direct and indirect effects when studying PLES_17921 impact on bacterial physiology?

Differentiating between direct and indirect effects of PLES_17921 on bacterial physiology requires a methodical experimental approach:

• Temporal analysis of effects:

  • Implement time-course experiments following PLES_17921 perturbation

  • Measure multiple physiological parameters at defined intervals

  • Primary (direct) effects typically occur more rapidly than secondary effects

  • Use statistical methods like principal component analysis to identify temporally clustered responses

• Dose-response relationships:

  • Create expression systems with titratable PLES_17921 levels

  • Plot physiological responses against PLES_17921 expression

  • Direct effects often show proportional relationships to protein levels

  • Indirect effects may exhibit threshold responses or non-linear relationships

• Genetic suppressor analysis:

  • Identify suppressors that rescue phenotypes of PLES_17921 mutants

  • Map these suppressors to specific pathways

  • Construct double mutants to establish epistatic relationships

  • Place PLES_17921 within genetic pathways based on suppression patterns

• Direct biochemical interaction testing:

  • Purify PLES_17921 and test direct interactions with candidate effector molecules

  • Measure binding affinities and kinetics using SPR or ITC

  • Reconstitute minimal systems in proteoliposomes to test sufficiency

  • Compare biochemical activity in the presence/absence of hypothesized interactors

• Systems biology approaches:

  • Integrate transcriptomics, proteomics, and metabolomics data

  • Apply network analysis to identify direct PLES_17921 connections

  • Use computational modeling to predict direct vs. cascade effects

  • Validate model predictions with targeted experiments

This comprehensive approach helps establish causality and distinguish between PLES_17921's direct functional roles and downstream consequences of these primary activities.

What emerging technologies could advance understanding of PLES_17921 structure-function relationships?

Several cutting-edge technologies show particular promise for elucidating PLES_17921 structure-function relationships:

• Cryo-electron microscopy advances:

  • Single-particle analysis for high-resolution structure determination

  • Time-resolved cryo-EM to capture conformational changes

  • In situ structural studies within membrane environments

  • Implementation of focused ion beam milling for visualizing PLES_17921 in native bacterial membranes

• Integrated structural biology approaches:

  • Hydrogen-deuterium exchange mass spectrometry to map dynamic regions

  • Solid-state NMR for studying membrane-embedded regions

  • X-ray free electron laser crystallography for time-resolved structural changes

  • Integrative modeling combining multiple low-resolution data types

• Advanced functional characterization methods:

  • Single-molecule FRET to monitor conformational dynamics

  • High-throughput mutagenesis coupled with deep sequencing for comprehensive structure-function mapping

  • Patch-clamp electrophysiology if PLES_17921 has channel-like properties

  • Native mass spectrometry for studying intact membrane protein complexes

• Computational methods:

  • Machine learning approaches for improved structure prediction

  • Molecular dynamics simulations in explicit membrane environments

  • Enhanced sampling methods to capture rare conformational states

  • Quantum mechanics/molecular mechanics (QM/MM) for studying active site chemistry

These emerging technologies would significantly advance our understanding of PLES_17921's molecular mechanisms and physiological roles, potentially revealing new therapeutic targets in Pseudomonas aeruginosa infections.

How might PLES_17921 research contribute to understanding antibiotic resistance mechanisms in Pseudomonas aeruginosa?

Research on PLES_17921 could provide valuable insights into antibiotic resistance mechanisms through several investigative pathways:

• Membrane permeability studies:

  • Determine if PLES_17921 affects membrane organization and permeability barriers

  • Measure antibiotic penetration rates in strains with varying PLES_17921 expression

  • Correlate membrane lipid composition changes with PLES_17921 levels

  • Examine potential interactions with porins that control antibiotic entry

• Efflux pump interaction analysis:

  • Investigate if PLES_17921 physically or functionally interacts with known efflux systems (MexAB-OprM, MexXY-OprM)

  • Measure efflux pump efficiency in PLES_17921 mutants

  • Determine if PLES_17921 affects proton motive force that drives efflux pumps

  • Test synergy between PLES_17921 inhibition and efflux pump inhibitors

• Stress response coordination:

  • Analyze if PLES_17921 participates in envelope stress responses that activate resistance mechanisms

  • Measure expression of PLES_17921 under antibiotic exposure

  • Determine if PLES_17921 influences biofilm formation in response to antibiotics

  • Examine potential roles in bacterial persistence

• Clinical isolate comparative studies:

  • Sequence PLES_17921 across resistant clinical isolates to identify variants

  • Correlate expression levels with resistance profiles

  • Test if PLES_17921 mutations confer selective advantages during antibiotic treatment

  • Examine strain-specific differences in PLES_17921 function

These research directions would significantly contribute to our understanding of the complex antibiotic resistance mechanisms in Pseudomonas aeruginosa, potentially identifying new therapeutic strategies for this significant pathogen.

What interdisciplinary approaches might reveal new functions or applications of PLES_17921 research?

Interdisciplinary approaches could uncover novel functions and applications of PLES_17921 through these methodological frameworks:

• Synthetic biology applications:

  • Engineer PLES_17921 variants with modified functions

  • Develop biosensors based on PLES_17921 conformational changes

  • Create synthetic signaling pathways incorporating PLES_17921

  • Design minimal bacterial systems to study essential membrane protein functions

• Immunological research interfaces:

  • Investigate PLES_17921 as a potential vaccine target

  • Study host immune recognition of PLES_17921

  • Develop antibodies or nanobodies targeting exposed PLES_17921 domains

  • Examine PLES_17921's role in host-pathogen interactions

• Structural bioinformatics integration:

  • Apply machine learning to predict functional relationships

  • Conduct evolutionary analysis across bacterial species

  • Identify structural motifs shared with proteins of known function

  • Model co-evolution networks to predict interaction partners

• Nanotechnology applications:

  • Develop PLES_17921-based nanopores for sensing applications

  • Create biomimetic membranes incorporating PLES_17921

  • Design targeted nanoparticles using PLES_17921-derived peptides

  • Explore potential in bioelectronic interfaces

• Systems pharmacology approach:

  • Screen for small molecules that specifically interact with PLES_17921

  • Develop combination therapies targeting PLES_17921 and related systems

  • Model network effects of PLES_17921 perturbation

  • Identify synthetic lethal interactions for therapeutic exploitation

These interdisciplinary approaches expand the impact of PLES_17921 research beyond basic science into potential applications in biotechnology, medicine, and synthetic biology.