Recombinant Saccharomyces cerevisiae Putative uncharacterized protein YHR045W (YHR045W)

What is YHR045W and where is it localized in yeast cells?

YHR045W is a putative protein of unknown function in Saccharomyces cerevisiae. Current evidence suggests it may play a role in iron metabolism and/or amino acid and carbohydrate metabolism. Localization studies using green fluorescent protein (GFP) fusion techniques have predominantly placed this protein in the endoplasmic reticulum (ER) .

Quantitative localization data from multiple experiments shows that under wild-type conditions (WT1, WT2, WT3), YHR045W predominantly localizes to the ER with scores ranging from 0.66 to 0.89, with secondary localization in the cytoplasm (scores 0.08-0.31) . This ER localization pattern remains relatively consistent across various experimental conditions, though the protein shows dynamic relocalization under specific stresses.

What genomic information is available for YHR045W?

YHR045W was identified as part of the Saccharomyces Genome Deletion Project, which generated a comprehensive library of yeast strains each lacking one non-essential gene . Among all mutants in the Yeast Phenome database, YHR045W deletion (yhr045w∆) shows the strongest phenotypic similarity to dap1 deletion mutants, suggesting potential functional relationships . The gene encoding YHR045W was characterized during the systematic genome annotation efforts, though its function remains to be fully elucidated despite extensive phenotypic screening.

How does YHR045W localization change under different experimental conditions?

Localization dynamics of YHR045W show interesting patterns under various experimental conditions. Under rapamycin treatment (RAP series), there is a notable shift in localization from the ER to mitochondria, with mitochondrial localization scores increasing from near 0 in wild-type conditions to as high as 0.48 at RAP620 . This suggests a possible stress-responsive role or function related to nutrient sensing pathways.

Additionally, the data table reveals that:

• Under wild-type conditions, the majority of YHR045W localizes to the ER (0.66-0.89) with minor cytoplasmic presence (0.08-0.31)

• Rapamycin treatment induces gradual relocalization to mitochondria (reaching 0.48 at RAP620)

• Hydroxyurea treatment (HU series) maintains predominantly ER localization with increased cytoplasmic presence

• The rpd3Δ background alters localization patterns significantly, with increased cytoplasmic localization (0.56)

What methods are most effective for studying YHR045W localization?

Fluorescence microscopy using GFP-fusion proteins has been the gold standard for determining YHR045W localization. The comprehensive data available shows quantitative scoring across multiple cellular compartments under various experimental conditions . For researchers interested in studying YHR045W localization:

• GFP-tagging at either N- or C-terminus can be employed, though C-terminal tagging appears to preserve native localization better based on the consistent ER patterns observed

• Immunofluorescence using specific antibodies could provide complementary data without the potential artifacts of fusion proteins

• Subcellular fractionation followed by western blotting could biochemically confirm the microscopy-based localization data

• Live-cell imaging would be particularly valuable for tracking the dynamic relocalization observed under stress conditions such as rapamycin treatment

The data indicate that examination under multiple stress conditions is essential, as the protein shows significant relocalization patterns that might provide functional insights.

How can researchers generate recombinant S. cerevisiae expressing modified YHR045W?

The generation of recombinant S. cerevisiae strains expressing modified YHR045W can be approached using several established methods:

• Homologous recombination-based gene replacement strategies, similar to those used in the Saccharomyces Genome Deletion Project, can be employed to introduce modifications at the native locus

• For expression studies, the whole recombinant approach used in therapeutic applications, such as in GI-4000 series development, provides a framework for producing modified proteins in yeast

• Gateway cloning or Gibson Assembly can be used to create various fusion constructs (N-terminal, C-terminal tags, or internal domain fusions)

• The CRISPR-Cas9 system has been successfully adapted for yeast and offers precise genome editing capabilities for introducing point mutations or domain deletions

When generating recombinant strains, researchers should consider:

• The potential impact of tags on protein function

• The choice between constitutive and inducible promoters based on experimental needs

• The importance of confirming expression levels and proper localization of the modified protein

• The selection of appropriate marker genes for strain construction and maintenance

What phenotypic screening approaches have been most informative for YHR045W characterization?

The systematic phenotypic screens conducted as part of the Yeast Phenome project provide valuable methodological insights for researchers studying YHR045W. Between November 2000 and May 2022, 366 research groups published 531 studies describing systematic testing of yeast knockout mutants under various conditions, generating data from 14,495 knockout screens .

Effective screening approaches include:

• Chemical genomic screens exposing yhr045w∆ strains to diverse compounds to identify condition-specific sensitivities

• Physical stressor screens (temperature, pH, osmotic stress) to identify stress-response roles

• Genetic interaction mapping through synthetic genetic array (SGA) analysis or synthetic dosage lethality (SDL) screens

• Growth rate measurements under various nutrient conditions, particularly focusing on iron availability or amino acid composition given the hypothesized role of YHR045W

• Microscopy-based screens to identify morphological abnormalities in deletion strains

The observation that yhr045w∆ shows strong phenotypic similarity to dap1∆ suggests that conditions known to affect DAP1 function might be particularly informative for YHR045W characterization .

What protein interactions have been identified or predicted for YHR045W?

While the search results do not provide direct evidence of specific protein interaction partners for YHR045W, several approaches can be inferred from methodologies applied to similar uncharacterized yeast proteins:

• Affinity purification coupled with mass spectrometry (AP-MS) would be the gold standard approach for identifying interaction partners

• Yeast two-hybrid screening could reveal binary protein interactions

• Proximity-based labeling approaches (BioID, APEX) could identify proteins in the same cellular neighborhood

• Genetic interaction screens may reveal functional relationships with other proteins

The strong phenotypic similarity between yhr045w∆ and dap1∆ suggests a potential functional relationship worth investigating . DAP1 (Damage Associated Protein 1) is involved in sterol metabolism and damage response, providing a potential starting point for interaction studies.

Computational approaches such as co-expression analysis across the extensive Yeast Phenome dataset could also predict potential interaction partners based on correlated phenotypic profiles.

How does YHR045W function relate to cellular stress response pathways?

The localization data reveal a striking pattern of YHR045W redistribution under various stress conditions, particularly its relocalization from the ER to mitochondria under rapamycin treatment . This suggests potential involvement in:

• TOR (Target Of Rapamycin) signaling pathway, a master regulator of cellular stress responses

• Mitochondrial stress response mechanisms

• ER stress response or unfolded protein response (UPR)

The relative distribution between compartments under different conditions:

This dynamic relocalization pattern suggests that YHR045W may play a role in cellular adaptation to stress, potentially functioning as a signaling component or stress-responsive factor that shuttles between organelles.

What computational predictions exist for YHR045W structure and function?

While the search results don't provide specific computational predictions for YHR045W structure, researchers can employ several bioinformatic approaches:

• Sequence-based predictions using tools like BLAST, Pfam, and InterPro to identify conserved domains

• Structural predictions using AlphaFold2 or RoseTTAFold

• Gene Ontology enrichment analysis based on phenotypic similarities with characterized genes

• Comparative genomics across yeast species to identify evolutionary patterns

The putative role in iron metabolism and/or amino acid metabolism mentioned in the description likely stems from computational predictions or high-throughput studies. Researchers could further investigate this connection through:

• Analysis of protein sequence for metal-binding motifs

• Identification of potential transmembrane domains consistent with ER localization

• Comparative analysis with known proteins involved in iron or amino acid metabolism

• Metabolomic profiling of deletion strains under various iron availability conditions

How can researchers interpret conflicting localization data for YHR045W?

The localization data for YHR045W shows some variations across experimental conditions that require careful interpretation . Key considerations include:

• Resolution of apparent conflicts between predominant ER localization in some conditions versus mitochondrial or cytoplasmic in others:

  • These may represent true biological dynamics rather than experimental artifacts

  • Time-course experiments could reveal temporal patterns of relocalization

  • Dual-color imaging with organelle markers could confirm partial co-localization

• Methodological approaches to resolve localization conflicts:

  • Super-resolution microscopy to distinguish between closely associated organelles

  • Correlative light and electron microscopy (CLEM) for ultrastructural confirmation

  • Biochemical fractionation with high purity organelle isolation

  • Multiple tagging strategies (N-terminal vs. C-terminal) to rule out tag interference

• Interpretation of numerical localization scores:

  • Scores represent probability distributions across compartments

  • Even low scores (0.05-0.10) may represent biologically meaningful minor populations

  • Changes in distribution patterns may be more informative than absolute values

What are the limitations of whole-genome deletion screens for studying YHR045W?

While the Yeast Knockout (YKO) collection has been invaluable for functional genomics, several limitations should be considered when interpreting data for YHR045W:

• Phenotypic masking due to genetic redundancy may obscure functions

• Adaptive responses during strain construction may compensate for gene loss

• The standard conditions used in many screens may not reveal condition-specific roles

• Batch effects and technical variations across the 14,495 screens in the Yeast Phenome dataset require careful normalization

More specialized approaches to overcome these limitations include:

• Construction of double or triple mutants to address redundancy

• Conditional alleles (temperature-sensitive, auxin-inducible degrons) for essential interaction partners

• Dosage-dependence studies using overexpression rather than deletion

• Acute depletion strategies to avoid adaptive responses

How can researchers design experiments to confirm hypothesized functions of YHR045W?

Based on the information available, several experimental approaches could help confirm potential functions of YHR045W:

• For the hypothesized role in iron metabolism:

  • Growth assays under iron limitation or excess

  • Measurement of intracellular iron levels in deletion strains

  • Analysis of iron-dependent enzyme activities

  • Transcriptomic analysis focusing on iron-responsive genes

• For the potential role in amino acid metabolism:

  • Metabolomic profiling of deletion strains

  • Growth assays in media lacking specific amino acids

  • Isotope labeling to track amino acid flux

• For understanding the significance of ER localization:

  • Analysis of ER stress responses in deletion strains

  • Investigation of protein glycosylation or other ER-specific processes

  • Examination of ER morphology and dynamics

• For investigating the relationship with DAP1:

  • Construction and characterization of double mutants

  • Comparative phenotypic analysis under various stress conditions

  • Investigation of shared genetic interactions or biochemical pathways

What emerging technologies could advance understanding of YHR045W function?

Several cutting-edge technologies show promise for further characterizing YHR045W:

• Spatial proteomics approaches such as LOPIT-DC (Localization of Organelle Proteins by Isotope Tagging after Differential ultraCentrifugation) for high-resolution mapping of protein localization

• Proximity labeling technologies like TurboID or APEX2 to identify neighboring proteins in the ER and mitochondria

• Single-cell proteomics to examine cell-to-cell variation in YHR045W expression and localization

• Cryo-electron tomography for visualizing YHR045W in its native cellular context

• Targeted protein degradation approaches (dTAG, AID) for acute depletion studies

How might YHR045W research contribute to broader understanding of eukaryotic cell biology?

Research on uncharacterized proteins like YHR045W contributes significantly to our understanding of eukaryotic cell biology:

• The strong phenotypic correlation between yhr045w∆ and dap1∆ exemplifies how systematic phenotypic analysis can reveal functional relationships between seemingly unrelated proteins

• The observed relocalization from ER to mitochondria under stress conditions highlights the dynamic nature of protein localization and inter-organelle communication

• Characterization of conserved uncharacterized proteins contributes to completing the functional annotation of the minimal eukaryotic genome

• Studies of YHR045W could reveal novel aspects of iron metabolism or amino acid processing in eukaryotes

The comprehensive phenotypic dataset in Yeast Phenome containing data from 14,495 knockout screens provides unprecedented opportunities for understanding gene function through integrative analysis .