Recombinant Saccharomyces cerevisiae Uncharacterized membrane protein YOL092W (YOL092W)

What is YOL092W and what is its predicted function in S. cerevisiae?

YOL092W is an uncharacterized membrane protein in Saccharomyces cerevisiae (baker's yeast) that belongs to the PQ loop repeat protein family. Based on sequence analysis and functional studies, it appears to be involved in non-selective cation channel activity. The protein contains 308 amino acids and has a molecular structure consistent with membrane-spanning domains.

The protein is thought to be responsible for cation flux across membranes, specifically in relation to non-selective cation movement. Sequence comparisons with proteins in other living systems suggest that YOL092W and its homologs may be important for maintaining ion homeostasis in the cell .

What is the amino acid sequence of YOL092W and how is it structurally characterized?

The complete amino acid sequence of YOL092W is:

MQLVPLELNRSTLSGISGSISISCWIIVFVPQIYENFYRKSSDGLSLLFVVLWLAGDVFNLMGAVMQHLLSTMIILAAYYTVADIILLGQCLWYDNEEKPAVDPIHLSPANPINENVLHDVFNEQQPLLNSQGQPNRIDEEMAAPSSDGNAGDDNLREVNSRNLIKDIFIVSGVVFVGFISWYVTYCVNYTQPPPVEDPSLPVPELQINWMAQIFGYLSALLYLGSRIPQILLNFKRKSCEGIFLFFLFACLGNTTFIFSVIVISLDWKYLIMNASWLVGSIGTLFMDFVIFSQFFIYKRNKKFILN

Structurally, YOL092W is characterized as a membrane protein with multiple transmembrane domains. It contains the highly conserved PQ loop motif, which is important for its function. The protein's structure suggests it forms a channel or transporter in the membrane, consistent with its proposed role in cation movement.

How can researchers obtain recombinant YOL092W protein for experimental studies?

Recombinant YOL092W protein can be obtained through:

• Commercial sources that produce the protein in expression systems, typically supplied in a storage buffer containing Tris-based buffer with 50% glycerol optimized for protein stability .

• In-house expression systems using yeast, bacterial, or insect cell expression vectors. For optimal expression of membrane proteins like YOL092W, researchers should consider:

  • Using expression tags that facilitate purification (His-tag, GST-tag)

  • Optimizing codon usage for the expression host

  • Employing detergents for membrane protein solubilization

  • Testing different induction conditions to maximize yield

When storing the recombinant protein, it should be kept at -20°C for regular use, or at -80°C for extended storage. Repeated freezing and thawing should be avoided, and working aliquots should be stored at 4°C for up to one week .

What experimental systems can be used to study YOL092W function?

Several experimental systems can be employed to study YOL092W function:

• Yeast knockout strains: Creating YOL092W deletion strains (∆YOL092W) to observe phenotypic changes related to cation tolerance, membrane potential, or growth under various ionic conditions.

• Electrophysiological approaches: Patch-clamp techniques can be used to measure ion conductance in membranes expressing YOL092W.

• Fluorescent ion indicators: These can be used to monitor changes in cation concentrations in wild-type versus knockout strains.

• Heterologous expression systems: Expressing YOL092W in other organisms or cell types that lack endogenous non-selective cation channels.

• Mutagenesis studies: Point mutations in conserved regions, particularly in the PQ loop motif, can help identify critical amino acids for function.

Strain comparisons have revealed differences in sensitivity to cations like methylammonium (MA+) between strains with different YOL092W alleles, suggesting this approach can be informative for functional characterization .

How does YOL092W interact with other proteins in the cation transport machinery of S. cerevisiae?

YOL092W likely functions as part of a complex network of proteins involved in cation homeostasis. Research approaches to study these interactions include:

• Protein-protein interaction studies:

  • Co-immunoprecipitation experiments with tagged YOL092W

  • Yeast two-hybrid screening to identify interaction partners

  • Proximity labeling techniques (BioID, APEX) to identify proteins in close proximity to YOL092W in the native membrane environment

• Genetic interaction studies:

  • Synthetic genetic array analysis to identify genes that interact functionally with YOL092W

  • Double knockout strains to identify compensatory mechanisms

• Transcriptomic analysis:

  • RNA sequencing of wild-type versus YOL092W mutants to identify coordinated gene expression patterns

  • Comparison of expression patterns under different ionic stress conditions

While specific interaction partners for YOL092W have not been fully characterized, research into other yeast membrane proteins suggests that non-selective cation channels often interact with proteins involved in secretory pathways, vesicular trafficking, and osmoregulation.

What role does YOL092W play in cation flux and how does sequence variation affect its function?

YOL092W appears to be involved in non-selective cation flux, as indicated by differences in methylammonium (MA+) toxicity phenotypes observed between yeast strains with different YOL092W alleles.

Sequence analysis of YOL092W from different S. cerevisiae strains has revealed polymorphisms that may affect protein function. For example, a Q30H substitution in strain 26972c2 occurs within the highly conserved first PQ loop repeat region and may be responsible for differences in MA+ tolerance between strains .

Research approaches to study the relationship between sequence variation and function include:

• Site-directed mutagenesis of conserved residues, particularly within the PQ loop motifs

• Creation of chimeric proteins with related cation channels

• Functional complementation experiments in different strain backgrounds

• Electrophysiological characterization of wild-type and mutant channels

Researchers should focus on the conserved PQ loop regions, as mutations in these areas are likely to have the most significant impact on channel function and cation flux.

How can structural biology approaches be used to elucidate YOL092W function?

Given that YOL092W is a membrane protein with limited structural characterization, several structural biology approaches can be employed:

• Cryo-electron microscopy (Cryo-EM):

  • Suitable for membrane proteins without requiring crystallization

  • Can resolve structures at near-atomic resolution

  • Sample preparation involves purification in detergent micelles or nanodiscs

• X-ray crystallography:

  • Requires production of well-ordered protein crystals

  • For membrane proteins like YOL092W, lipidic cubic phase crystallization may be optimal

  • Typically requires large amounts of highly pure protein

• Nuclear Magnetic Resonance (NMR) spectroscopy:

  • Suitable for studying dynamics and conformational changes

  • May be challenging for full-length YOL092W due to size limitations

  • Can focus on specific domains or regions of interest

• Computational modeling:

  • Homology modeling based on related proteins with known structures

  • Molecular dynamics simulations to predict ion conduction pathways

  • Integration with experimental data for validation

For successful structural studies, researchers should optimize expression systems to produce sufficient quantities of properly folded protein, carefully select appropriate detergents or lipid environments, and consider using stabilizing mutations or antibody fragments to facilitate structure determination.

What transcriptional changes occur in S. cerevisiae strains expressing recombinant YOL092W under different growth conditions?

To study transcriptional changes associated with YOL092W expression, researchers can employ:

• RNA sequencing (RNA-Seq):

  • Compare transcriptome profiles between wild-type and YOL092W-overexpressing strains

  • Analyze differential expression under various ionic stress conditions

  • Identify co-regulated gene networks

• Real-time quantitative PCR (RT-qPCR):

  • Validate expression changes in selected genes

  • Monitor temporal changes in expression

  • Compare results with microarray or RNA-Seq data

• Promoter-reporter fusion assays:

  • Use GFP or luciferase reporters to monitor YOL092W promoter activity

  • Test different environmental conditions and stressors

Based on studies of related membrane proteins in S. cerevisiae, expression of genes involved in ion homeostasis often correlates with changes in environmental conditions. For example, in xylose-metabolizing S. cerevisiae strains, genes encoding tricarboxylic acid cycle enzymes, respiratory proteins, and regulatory proteins (like HAP4 and MTH1) show significant expression changes under different carbon sources and oxygen conditions .

Similar approaches could identify transcriptional networks associated with YOL092W function, particularly under conditions that challenge cellular ion homeostasis.

What are the optimal conditions for expression and purification of recombinant YOL092W?

For optimal expression and purification of recombinant YOL092W, researchers should consider:

• Expression system selection:

  • Yeast expression systems (particularly S. cerevisiae) maintain native post-translational modifications

  • Pichia pastoris often yields higher protein quantities for membrane proteins

  • E. coli systems with specialized strains (like C41/C43) can be used with proper optimization

  • Insect cell/baculovirus systems balance yield and eukaryotic processing

• Expression construct design:

  • Include affinity tags (His6, FLAG, etc.) for purification

  • Consider fusion partners to enhance solubility (MBP, SUMO, etc.)

  • Include protease cleavage sites to remove tags post-purification

  • Optimize codon usage for the chosen expression system

• Membrane protein extraction:

  • Test various detergents (DDM, LMNG, digitonin) for optimal solubilization

  • Consider nanodiscs or styrene-maleic acid lipid particles (SMALPs) for native-like lipid environment

  • Use gentle extraction conditions to maintain protein folding and activity

• Purification strategy:

  • Begin with affinity chromatography based on the chosen affinity tag

  • Follow with size exclusion chromatography to remove aggregates

  • Consider ion exchange chromatography for further purification

  • Verify protein quality by SDS-PAGE and Western blotting

• Storage conditions:

  • Store in Tris-based buffer with 50% glycerol at -20°C or -80°C

  • Avoid repeated freeze-thaw cycles

  • Keep working aliquots at 4°C for up to one week

How can researchers assess the ion channel activity of YOL092W in vitro and in vivo?

Assessment of YOL092W ion channel activity can be performed using multiple complementary approaches:

• In vitro electrophysiological methods:

  • Patch-clamp recordings of cells or reconstituted systems expressing YOL092W

  • Planar lipid bilayer recordings with purified and reconstituted protein

  • Liposome-based ion flux assays using fluorescent indicators

  • Solid-supported membrane electrophysiology for high-throughput screening

• In vivo functional assays:

  • Growth phenotyping under different ionic conditions

  • Methylammonium (MA+) toxicity assays, which have previously revealed differences between strains with variation in YOL092W

  • Membrane potential measurements using voltage-sensitive dyes

  • Intracellular ion concentration measurements using specific fluorescent probes

• Genetic approaches:

  • Complementation studies in strains lacking endogenous YOL092W

  • Dominant-negative mutant expression to disrupt channel function

  • Conditional expression systems to control timing of YOL092W expression

• Biophysical characterization:

  • Isothermal titration calorimetry to measure ion binding affinities

  • Structural changes upon ion binding using fluorescence spectroscopy

  • Conformational dynamics using hydrogen-deuterium exchange mass spectrometry

Researchers should combine multiple approaches to build a comprehensive understanding of YOL092W ion channel properties, including ion selectivity, gating mechanisms, and regulatory factors.

What genetic engineering strategies can be employed to study YOL092W function in S. cerevisiae?

Several genetic engineering strategies can be used to study YOL092W function:

• Gene deletion and replacement:

  • CRISPR-Cas9 based knockout of YOL092W

  • Marker-based gene replacement techniques

  • Introduction of mutant alleles at the native locus using homologous recombination

• Controlled expression systems:

  • Galactose-inducible promoters for controlled expression

  • Tetracycline-responsive elements for dose-dependent expression

  • Estradiol-inducible systems for tight regulation

  • Copper-inducible promoters like CUP1 for metal-dependent expression

• Protein tagging strategies:

  • C-terminal or N-terminal fusion with fluorescent proteins for localization studies

  • Epitope tagging for immunodetection and purification

  • Split protein complementation for interaction studies

  • FRET-based biosensors to detect conformational changes

• Strain engineering:

  • Creation of respiration-deficient (petite) mutants to study respiratory influence on YOL092W function, similar to approaches used in other S. cerevisiae studies

  • Multiple gene deletions to study genetic interactions

  • Engineering of strains with altered membrane composition

• Genome-wide screens:

  • Synthetic genetic array analysis to identify genetic interactions

  • High-throughput phenotypic screening of YOL092W mutant libraries

  • Suppressor screens to identify compensatory mutations

Researchers should note that strain background can significantly affect phenotypes, as demonstrated by the differences in cation sensitivity between strains with different YOL092W alleles .

How might understanding YOL092W function contribute to broader knowledge of membrane transport in eukaryotes?

Research on YOL092W has potential implications for understanding fundamental aspects of membrane transport:

• Conservation and evolution of cation transport mechanisms:

  • Sequence similarities between YOL092W and proteins in other living systems suggest conserved mechanisms across species

  • Comparative studies could reveal evolutionary relationships between different transporter families

  • Identification of core functional elements in membrane transport proteins

• Membrane protein structural biology:

  • Structure determination of YOL092W could provide insights into general principles of ion channel architecture

  • Understanding of the PQ loop repeat structural motif and its role in channel function

  • Mechanisms of ion selectivity and gating in non-selective cation channels

• Cellular ion homeostasis networks:

  • Integration of YOL092W into broader cellular signaling networks

  • Cross-talk between different ion transport systems

  • Coordination of ion transport with cellular metabolic state

• Application to human disease models:

  • Human homologs of YOL092W might be implicated in channelopathies

  • Yeast as a model system for studying disease-associated mutations in conserved channels

  • Development of screening platforms for channel modulators with therapeutic potential

Research approaches should focus on integrating structural, functional, and systems-level analyses to place YOL092W within the broader context of eukaryotic membrane transport biology.

What are the potential relationships between YOL092W and cellular respiration in S. cerevisiae?

The relationship between YOL092W and cellular respiration presents an intriguing research direction:

• Potential metabolic connections:

  • Non-selective cation channels can influence membrane potential, potentially affecting mitochondrial function

  • Ion gradients maintained by channels like YOL092W might impact respiratory chain activity

  • Cytosolic cation levels can affect enzyme activities throughout metabolism

• Research approaches to investigate this relationship:

  • Comparative studies of YOL092W activity in respiratory-competent and respiratory-deficient (petite) mutants

  • Analysis of YOL092W expression under fermentative versus respiratory growth conditions

  • Measurement of respiratory parameters in YOL092W mutant strains

• Relevance to carbon source utilization:

  • Studies on recombinant S. cerevisiae have shown that different carbon sources (like glucose versus xylose) induce different respiratory responses

  • Expression of genes encoding tricarboxylic acid cycle and respiration pathway enzymes increases during metabolism of non-fermentable carbon sources

  • YOL092W's role may vary depending on the metabolic state of the cell

Research in this area could benefit from approaches similar to those used to study respiratory responses in xylose-metabolizing S. cerevisiae, including transcriptome analysis under different growth conditions and characterization of respiration-deficient mutants .

How can computational approaches enhance our understanding of YOL092W structure and function?

Computational approaches offer powerful tools for studying membrane proteins like YOL092W:

• Structural prediction and modeling:

  • AlphaFold2 and RoseTTAFold can predict 3D structures based on primary sequence

  • Molecular dynamics simulations to model protein behavior in membrane environments

  • Docking studies to predict ion binding sites and interaction partners

  • Homology modeling based on related proteins with known structures

• Functional prediction:

  • Machine learning approaches to predict functional sites from sequence conservation

  • Network analysis to place YOL092W in broader cellular pathways

  • Simulation of ion conduction through predicted channel structures

  • Prediction of critical residues for channel function through evolutionary analysis

• System-level modeling:

  • Integration of YOL092W into whole-cell models of S. cerevisiae

  • Flux balance analysis to predict metabolic impacts of YOL092W activity

  • Multi-scale modeling connecting molecular function to cellular phenotypes

• Experimental design optimization:

  • In silico mutagenesis to prioritize variants for experimental testing

  • Virtual screening for potential channel modulators

  • Optimization of protein expression constructs based on predicted folding properties

Researchers should integrate computational predictions with experimental validation, using iterative approaches to refine models and generate new hypotheses about YOL092W function.

What are the common challenges in working with YOL092W and how can they be overcome?

Researchers working with membrane proteins like YOL092W frequently encounter specific challenges:

• Low expression yields:

  • Optimize codon usage for the expression host

  • Test different promoters and expression conditions

  • Consider fusion with well-expressed partner proteins

  • Use specialized strains designed for membrane protein expression

  • Implement fed-batch or continuous culture systems for higher biomass

• Protein aggregation and misfolding:

  • Screen multiple detergents for optimal solubilization

  • Include stabilizing additives (glycerol, specific lipids)

  • Lower expression temperature to slow folding

  • Consider nanodiscs or other membrane mimetics for native-like environment

  • Test expression of truncated constructs or individual domains

• Functional assay limitations:

  • Combine multiple complementary assay types for validation

  • Include positive and negative controls in all experiments

  • Optimize assay conditions (buffer composition, pH, temperature)

  • Consider background activity in the chosen experimental system

  • Develop robust normalization methods for comparative studies

• Difficulties in structural characterization:

  • Try different membrane mimetics (detergents, nanodiscs, amphipols)

  • Engineer constructs with enhanced stability

  • Remove flexible regions that may hinder crystallization

  • Use conformation-specific antibodies or nanobodies to stabilize specific states

  • Consider cryo-EM as an alternative to crystallography

• Genetic manipulation challenges:

  • Account for strain background effects on phenotype

  • Use markerless systems to avoid marker effects

  • Consider essential gene complementation strategies if knockouts are lethal

  • Implement inducible systems for toxic constructs

By anticipating these challenges and implementing appropriate strategies, researchers can enhance the success rate of experiments involving YOL092W.

How can researchers differentiate between phenotypes specifically related to YOL092W and general membrane disruption effects?

Distinguishing specific YOL092W-related phenotypes from general membrane disruption requires careful experimental design:

• Control selection:

  • Include knockouts of other membrane proteins with different functions

  • Use point mutants that specifically disrupt YOL092W function rather than complete deletions

  • Compare multiple independently generated mutant strains

  • Include complementation controls (rescue experiments)

• Specificity testing:

  • Analyze responses to specific ion challenges versus general membrane stressors

  • Perform dose-response experiments to identify threshold effects

  • Use membrane integrity assays to rule out general membrane damage

  • Test for off-target effects using transcriptomics or proteomics

• Selective inhibition approaches:

  • Develop specific inhibitors or modulators of YOL092W

  • Use inducible degron systems for rapid protein depletion

  • Implement chemical-genetic approaches with engineered sensitivity

• Temporal analysis:

  • Monitor phenotype development over time after YOL092W perturbation

  • Use systems with acute versus chronic disruption of function

  • Correlate phenotypes with measured protein levels or activity

• Structure-function studies:

  • Create a panel of mutations affecting different aspects of protein function

  • Compare phenotypes across mutations to identify specific functional domains

  • Use chimeric proteins to map functional regions

These approaches collectively provide stronger evidence for YOL092W-specific effects versus general membrane perturbations.