Recombinant Saccharomyces cerevisiae Uncharacterized mitochondrial carrier AWRI1631_61110 (AWRI1631_61110)

What is the predicted function of the uncharacterized mitochondrial carrier AWRI1631_61110?

The AWRI1631_61110 belongs to the mitochondrial carrier family (MCF), a group of proteins that transport metabolites, nucleotides, and cofactors across the inner mitochondrial membrane. While its specific substrate remains uncharacterized, analysis of its amino acid sequence and comparison with known carriers can provide preliminary functional predictions. Mitochondrial carriers in S. cerevisiae typically contain three tandem repeats of approximately 100 amino acids, each containing two transmembrane α-helices linked by a large loop with a conserved signature motif P-X-[DE]-X-X-[RK] . Based on sequence homology and conserved binding site residues, particularly at "contact point II," this carrier likely transports specific metabolites between the mitochondrial matrix and cytosol, potentially including nucleotides, amino acids, or organic acids depending on its binding site characteristics.

How does AWRI1631_61110 compare structurally to characterized mitochondrial carriers?

Like other mitochondrial carriers, AWRI1631_61110 likely adopts a barrel-like structure with six transmembrane α-helices showing pseudo-3-fold symmetry. The protein would exist in two conformational states: the cytoplasmic state (c-state) that accepts substrate from the cytoplasm, and the matrix state that accepts substrate from the mitochondrial matrix . The structure likely features proline residues from the signature motif that kink the transmembrane helices, bringing their C-terminal ends together at the base of the cavity, with charged residues forming salt bridges that must be broken for substrate translocation .

What approaches should be used for initial classification of AWRI1631_61110?

To classify AWRI1631_61110, researchers should:

• Perform sequence alignment with known mitochondrial carriers using BLAST and multiple sequence alignment tools

• Analyze the conservation of key residues at the common substrate binding site, especially at contact point II

• Construct phylogenetic trees to establish evolutionary relationships with characterized carriers

• Examine the residues forming the binding site, as these can predict substrate specificity

• Compare with human orthologs to leverage cross-species functional information

What genetic manipulation techniques are most effective for studying AWRI1631_61110 function?

For comprehensive functional analysis of AWRI1631_61110, employ multiple complementary genetic approaches:

• Gene deletion: Create knockout strains using homologous recombination with selective markers to assess growth phenotypes under various conditions

• Overexpression: Generate strains with increased expression under control of promoters like GAL1 to observe gain-of-function phenotypes

• Epitope tagging: Add tags like HA, FLAG, or GFP to track localization and enable co-immunoprecipitation

• Site-directed mutagenesis: Target conserved residues in the substrate binding site to alter specificity

• Heterologous expression: Express the carrier in other organisms or in reconstituted liposomes for transport assays

The combined data from these approaches will help establish the carrier's role in cellular metabolism and identify its substrate specificity.

What metabolomic approaches can be used to identify the substrate of AWRI1631_61110?

To identify the substrate of this uncharacterized carrier, employ a multi-faceted metabolomic strategy:

• Comparative metabolomics: Compare metabolite profiles between wild-type and deletion strains using LC-MS/MS and GC-MS

• Isotope labeling: Track labeled substrates to identify altered metabolic fluxes in deletion mutants

• Transport assays: Reconstitute the purified carrier in liposomes to directly measure transport of candidate substrates

• Metabolic flux analysis: Use 13C-labeled substrates to quantify changes in flux through central carbon metabolism

• Metabolite accumulation: Analyze changes in cytosolic versus mitochondrial metabolite ratios

How can protein-protein interactions of AWRI1631_61110 be effectively mapped?

To map the protein interaction network of AWRI1631_61110:

• Affinity purification coupled with mass spectrometry: Using epitope-tagged versions of the carrier to isolate protein complexes

• Yeast two-hybrid screening: To identify direct binding partners

• Proximity labeling: Using BioID or APEX2 fused to the carrier to label proximal proteins in the native environment

• Co-immunoprecipitation: With antibodies against the tagged carrier followed by western blotting for suspected interaction partners

• Bimolecular fluorescence complementation: To visualize interactions in living cells

These approaches should be performed under various metabolic conditions, as carrier interactions may be dynamic and substrate-dependent.

How can computational approaches aid in predicting the substrate of AWRI1631_61110?

Computational prediction of AWRI1631_61110's substrate should utilize:

• Homology modeling: Build a 3D model based on the known structure of the ADP/ATP translocase

• Binding site analysis: Examine the conservation of residues at the common substrate binding site, particularly at contact point II, which can indicate whether the carrier transports nucleotides, amino acids, or keto acids

• Molecular docking: Screen potential substrates in silico by docking them to the predicted binding site

• Molecular dynamics simulations: Analyze the stability of substrate-carrier complexes

• Evolutionary analysis: Identify selective pressure on specific residues that might indicate substrate specificity

For example, if the carrier has contact point II residues typical of adenine nucleotide carriers (like YIL006w), it may transport nucleotides rather than keto acids or amino acids .

What is the predicted transport mechanism for AWRI1631_61110?

Based on general principles of mitochondrial carrier function, AWRI1631_61110 likely operates through:

• Alternating access mechanism: The carrier alternates between cytoplasmic (c-state) and matrix states, with the substrate binding site accessible from opposite sides of the membrane in each state

• Salt bridge disruption: Substrate binding likely disrupts salt bridges formed by the charged residues of the signature motif P-X-[DE]-X-X-[RK], allowing conformational change

• Specificity determinants: The residues at contact point II and other conserved positions in the binding site determine substrate specificity

• Exchange mechanism: The carrier likely catalyzes an exchange of substrates rather than unidirectional transport

Understanding this mechanism requires determining whether the carrier functions as a uniporter, symporter, or antiporter, and identifying any coupling ions.

How would you distinguish between primary and secondary effects of AWRI1631_61110 deletion?

To differentiate primary from secondary effects of AWRI1631_61110 deletion:

• Acute inactivation: Use temperature-sensitive alleles or chemical-genetic approaches for rapid inactivation

• Time-course analysis: Monitor metabolic changes immediately following inactivation

• Suppressor screening: Identify mutations that rescue deletion phenotypes

• Metabolic flux analysis: Use 13C-labeling to quantify changes in metabolic fluxes

• Complementation testing: Express homologous carriers to identify which can rescue function

Primary effects will manifest immediately after carrier inactivation and directly involve its substrate, while secondary effects emerge later as downstream metabolic adjustments.

What techniques are most suitable for resolving the structure of AWRI1631_61110?

For structural determination of AWRI1631_61110:

• X-ray crystallography: Requires purification and crystallization, challenging for membrane proteins but can provide high-resolution structures

• Cryo-electron microscopy: Increasingly powerful for membrane proteins, without crystallization requirements

• NMR spectroscopy: Suitable for dynamics studies but challenging for full structure determination

• Hydrogen-deuterium exchange mass spectrometry: Provides information on solvent accessibility and conformational changes

• Cross-linking coupled with mass spectrometry: Identifies spatial relationships between protein regions

Each technique has advantages for specific aspects of carrier structure:

How can structure-function relationships be established for AWRI1631_61110?

To establish structure-function relationships:

• Alanine scanning mutagenesis: Systematically replace conserved residues with alanine to identify essential positions

• Chimera construction: Create fusion proteins with parts from characterized carriers to map functional domains

• Directed evolution: Apply selective pressure to identify mutations that alter specificity or activity

• Cross-linking studies: Identify residues that interact with substrates

• Complementation analysis: Test whether expression of AWRI1631_61110 can rescue phenotypes of strains lacking other carriers

These approaches should focus particularly on the conserved binding site residues at contact point II and other positions known to determine substrate specificity in characterized carriers .

What approaches can reveal the conformational changes during substrate transport?

To study conformational changes during transport:

• Single-molecule FRET: Attach fluorophores to track distance changes between protein regions during transport

• Electron paramagnetic resonance (EPR) spectroscopy: Use spin labels to measure distances between specific residues

• Hydrogen-deuterium exchange mass spectrometry: Monitor changes in solvent accessibility during transport

• Molecular dynamics simulations: Model conformational transitions computationally

• Chemical cross-linking: Capture specific conformational states using cross-linkers of defined length

These techniques can help determine how AWRI1631_61110 alternates between cytoplasmic and matrix-facing conformations during substrate transport.

How does AWRI1631_61110 differ among S. cerevisiae strains?

To analyze strain variation in AWRI1631_61110:

• Comparative genomics: Analyze sequence conservation across diverse S. cerevisiae strains, particularly comparing laboratory, wild, and industrial strains

• Copy number variation analysis: Determine whether the gene shows CNV across strains, which is common in S. cerevisiae

• Selection pressure analysis: Calculate Ka/Ks ratios to identify positions under purifying or positive selection

• Association studies: Correlate sequence variations with phenotypic differences between strains

• Functional complementation: Test whether variants from different strains can interchangeably rescue deletion phenotypes

The AWRI1631 strain is likely a wine strain , so comparing this carrier with homologs in other industrial and laboratory strains may reveal adaptations specific to fermentation environments.

What can comparative analysis with other yeasts reveal about AWRI1631_61110 function?

Comparative analysis across yeast species can reveal:

• Functional conservation: Whether orthologs exist in other Saccharomyces species and non-conventional yeasts

• Evolutionary rate: Whether the protein evolves faster or slower than other mitochondrial carriers

• Lineage-specific adaptations: Identifying variations that correlate with metabolic differences between species

• Horizontal gene transfer: Assessing whether the carrier shows evidence of introgression from other species

• Coevolution with metabolic pathways: Correlating carrier evolution with changes in metabolic capabilities

Analysis should include close relatives (S. paradoxus, S. mikatae, S. kudriavzevii) and more distant species to establish evolutionary patterns .

How can orthology mapping help predict the function of AWRI1631_61110?

To leverage orthology for functional prediction:

• Reciprocal BLAST searches: Identify true orthologs in other organisms

• Phylogenetic profiling: Correlate the presence/absence of the carrier with specific metabolic capabilities

• Synteny analysis: Examine whether gene neighborhood is conserved across species

• Functional data integration: Incorporate experimental data from characterized orthologs

• Human ortholog identification: Determine whether a human ortholog exists and what is known about its function or disease associations

These analyses can place AWRI1631_61110 in the context of the mitochondrial carrier family evolution and potentially connect it to characterized carriers in other organisms.

How does AWRI1631_61110 contribute to mitochondrial metabolism in S. cerevisiae?

To determine the role of AWRI1631_61110 in mitochondrial metabolism:

• Growth phenotyping: Assess growth of deletion strains on different carbon sources (fermentable vs. non-fermentable)

• Mitochondrial respiration: Measure oxygen consumption rates in wild-type vs. deletion strains

• Metabolite profiling: Analyze changes in TCA cycle intermediates and related metabolites

• Mitochondrial membrane potential: Determine whether carrier deletion affects ΔΨm

• Stress responses: Test sensitivity to oxidative stress, osmotic stress, and temperature changes

The carrier's role may be particularly important during specific metabolic states, such as during the diauxic shift or under nutrient limitation.

What is the role of AWRI1631_61110 in carbon metabolism and fermentation?

To investigate the carrier's role in carbon metabolism:

• Fermentation profiling: Compare fermentation kinetics and end-products between wild-type and deletion strains

• Carbon flux analysis: Use 13C-labeled substrates to track metabolic fluxes through glycolysis, the TCA cycle, and anaplerotic pathways

• Gene expression analysis: Examine how deletion affects expression of carbon metabolism genes

• Metabolite exchange: Measure exchange of carbon compounds between cytosol and mitochondria

• Wine fermentation trials: If AWRI1631 is a wine strain, assess the impact on wine quality parameters

Since AWRI1631 is likely a wine strain, this carrier may have evolved specific functions related to fermentation efficiency or stress tolerance during wine production.

How does AWRI1631_61110 interact with other mitochondrial carriers in metabolic networks?

To understand carrier interactions within metabolic networks:

• Double deletion analysis: Create strains lacking AWRI1631_61110 and other carriers (e.g., MPC1, MPC3, OAC1, DIC1, SFC1) to identify synthetic interactions

• Overexpression screening: Test whether overexpression of other carriers can compensate for AWRI1631_61110 deletion

• Metabolic modeling: Incorporate the carrier into genome-scale metabolic models

• Transcriptional coordination: Analyze co-expression patterns with other carriers across conditions

• Substrate competition assays: Determine whether substrates of known carriers affect AWRI1631_61110 function

For example, if AWRI1631_61110 transports a metabolite like pyruvate, it may have functional relationships with the mitochondrial pyruvate carrier complex (MPC1/MPC2/MPC3) .

How can understanding AWRI1631_61110 function contribute to metabolic engineering of S. cerevisiae?

AWRI1631_61110 characterization can inform metabolic engineering by:

• Pathway optimization: Modifying carrier expression to redirect metabolic fluxes

• Bottleneck identification: Determining whether the carrier limits production of specific metabolites

• Stress tolerance engineering: Enhancing tolerance to fermentation stresses if the carrier transports protective compounds

• Substrate specificity engineering: Mutating the carrier to transport non-native substrates

• Compartmentalization strategies: Using the carrier to control metabolite distribution between cytosol and mitochondria

If the carrier transports compounds relevant to industrial fermentation (like organic acids), engineering its expression or specificity could enhance production of value-added compounds.

What implications does AWRI1631_61110 function have for understanding mitochondrial diseases in humans?

Understanding this carrier may provide insights into human mitochondrial function:

• Human ortholog identification: Determine whether AWRI1631_61110 has a human ortholog

• Disease mechanism modeling: Use yeast as a model system to study mechanisms of mitochondrial diseases

• Functional conservation testing: Express human orthologs in yeast deletion strains to test complementation

• Drug screening: Develop yeast-based assays to screen compounds that modulate carrier function

• Mutation consequence prediction: Use the yeast system to test effects of mutations found in human patients

Mitochondrial carrier mutations in humans are associated with various diseases, including opthalmoplegia, microcephaly, and metabolic disorders , so understanding this family has medical relevance.

What novel experimental systems could be developed to study AWRI1631_61110 in isolation?

Advanced experimental systems for isolated study include:

• Reconstituted liposome systems: Purify the carrier and reconstitute in artificial membrane vesicles for controlled transport assays

• Nanodiscs: Incorporate the carrier into nanodiscs for structural and functional studies in a native-like membrane environment

• Microfluidic devices: Develop microfluidic platforms to measure transport at the single-vesicle level

• Optogenetic regulation: Engineer light-controlled variants to precisely control carrier activity

• Cell-free expression systems: Produce the carrier in cell-free systems for rapid testing of variants

These systems allow precise control over the experimental environment, enabling detailed mechanistic studies that would be difficult in the complex cellular context.