Recombinant Lachancea thermotolerans Nuclear rim protein 1 (NUR1)

What is Lachancea thermotolerans Nuclear rim protein 1 (NUR1)?

Lachancea thermotolerans Nuclear rim protein 1 (NUR1) is a protein associated with the nuclear rim in the yeast species Lachancea thermotolerans. This protein consists of 592 amino acids and has been identified with the UniProt ID C5E3S7. The full-length recombinant protein can be produced with an N-terminal His tag through expression in E. coli systems. NUR1 is part of the cellular machinery in L. thermotolerans, which is a yeast species that has gained significant interest in ecological, evolutionary, and industrial research, particularly for its unique metabolic capabilities including high lactic acid production compared to other yeasts .

What expression systems are optimal for recombinant L. thermotolerans NUR1 production?

For the recombinant production of Lachancea thermotolerans NUR1, Escherichia coli has been demonstrated as an effective expression system. The full-length protein (amino acids 1-592) has been successfully expressed with an N-terminal His tag in E. coli. This approach allows for efficient protein production and subsequent purification using affinity chromatography techniques. The recombinant protein can be produced in sufficient quantities for various research applications while maintaining its structural integrity .

When designing an expression strategy, researchers should consider the following methodological approaches:

• Codon optimization for E. coli expression

• Selection of appropriate promoter systems (e.g., T7)

• Optimization of induction conditions (temperature, inducer concentration)

• Addition of solubility-enhancing tags or fusion partners if solubility issues arise

What purification and storage protocols maintain NUR1 stability?

Purification of recombinant His-tagged NUR1 can be achieved through standard nickel affinity chromatography followed by additional purification steps if higher purity is required. After purification, the protein can be prepared as a lyophilized powder for long-term storage. For optimal stability, the following storage protocol is recommended:

• Store the lyophilized protein at -20°C/-80°C upon receipt

• Aliquot the reconstituted protein to avoid repeated freeze-thaw cycles

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

• Add glycerol to a final concentration of 5-50% (50% is recommended as default)

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

• For long-term storage, keep aliquots at -20°C/-80°C

The protein is stable in Tris/PBS-based buffer containing 6% Trehalose at pH 8.0, which helps maintain protein integrity during storage .

How can researchers assess the quality of purified recombinant NUR1?

To ensure the quality and integrity of purified recombinant NUR1, researchers should implement a multi-step quality control process:

• Purity assessment: SDS-PAGE analysis should demonstrate greater than 90% purity, which is the standard specification for high-quality recombinant proteins .

• Western blot verification: Using antibodies against the His-tag or specific epitopes of NUR1 to confirm the identity of the purified protein.

• Mass spectrometry analysis: For precise molecular weight determination and confirmation of the amino acid sequence.

• Functional assays: Depending on the known or hypothesized functions of NUR1, specific assays can be developed to assess its biological activity.

• Structural integrity: Circular dichroism (CD) spectroscopy to evaluate secondary structure content and proper folding.

What is the predicted cellular function of NUR1 in L. thermotolerans?

While specific research on NUR1 function in L. thermotolerans is limited in the available literature, its localization to the nuclear rim suggests potential roles in nuclear organization, structure, or transport. By analogy with other nuclear rim proteins in yeasts, NUR1 may be involved in:

• Nuclear envelope structure and integrity

• Nucleocytoplasmic transport

• Chromatin organization and gene expression regulation

• Cell cycle progression and nuclear division

To definitively determine NUR1's function, researchers would need to conduct targeted studies including gene knockout/knockdown experiments, localization studies, and protein-protein interaction analyses .

How does NUR1 potentially contribute to L. thermotolerans adaptation to fermentative environments?

L. thermotolerans has undergone significant adaptation to fermentative environments, particularly in winemaking settings. Recent genomic and phenomic studies have revealed that this adaptation process has led to changes in genes involved in alternative carbon and nitrogen source assimilation, such as MAL1 and DAL5, which confer greater fitness in the winemaking environment .

While the direct role of NUR1 in this adaptation process has not been specifically documented in the available research, nuclear proteins often play crucial roles in transcriptional regulation and genome organization that could facilitate adaptation to changing environments. The regulation of gene expression under anaerobic or fermentative conditions in L. thermotolerans shows significant changes compared to Saccharomyces cerevisiae, with stronger modification in expression profiles .

Under anaerobic conditions, particularly in mixed cultures, L. thermotolerans activates processes related to nutrient uptake, filamentous growth (as a response to starvation), and iron homeostasis. Additionally, cellular wall components are significantly affected, with activation of genes for biogenesis and stabilization through β-glucan synthesis. These adaptive responses could potentially involve nuclear regulatory proteins like NUR1, though direct evidence for this involvement requires further investigation .

What experimental approaches are most effective for studying NUR1 function?

To comprehensively study NUR1 function in L. thermotolerans, researchers should consider a multi-faceted experimental approach:

• Gene deletion/disruption studies: Using CRISPR-Cas9 or traditional gene disruption methods to create NUR1 knockout strains and characterize the resulting phenotypes under various growth conditions.

• Localization studies: Fluorescent protein tagging (e.g., GFP fusion) to confirm the nuclear rim localization and monitor any dynamic changes in localization under different conditions.

• Protein-protein interaction studies:

  • Co-immunoprecipitation to identify interaction partners

  • Yeast two-hybrid screens to map the interaction network

  • BioID or proximity labeling to identify proteins in close proximity to NUR1

• Transcriptomic analysis: RNA-seq of wild-type vs. NUR1 mutant strains to identify genes whose expression is affected by NUR1 function.

• Chromatin association studies: ChIP-seq (if NUR1 directly interacts with chromatin) to map genomic binding sites.

• Structural biology approaches: Cryo-EM or X-ray crystallography to determine the three-dimensional structure, which could provide insights into function.

How does NUR1 compare between different Lachancea species and other yeasts?

Comparative analysis of nuclear proteins across different yeast species can provide valuable insights into their evolutionary conservation and functional importance. While specific comparative studies of NUR1 across Lachancea species are not detailed in the available research, the genomic and phenotypic diversity observed within L. thermotolerans suggests potential variation in nuclear proteins as well.

The Lachancea genus diverged after the appearance of anaerobic capability but prior to the whole-genome duplication event in the Saccharomyces lineage. This evolutionary position makes Lachancea species, including L. thermotolerans, particularly interesting for studying the evolution of nuclear organization in relation to metabolic adaptation .

To conduct a comprehensive comparative analysis of NUR1, researchers would need to:

• Identify NUR1 homologs across Lachancea species and other yeasts through sequence similarity searches

• Perform phylogenetic analysis to reconstruct the evolutionary history of the protein

• Compare sequence conservation across functional domains

• Analyze expression patterns across species under similar conditions

What role might NUR1 play in the genomic adaptation of L. thermotolerans to different environments?

Recent studies on L. thermotolerans have revealed significant genomic adaptation to different environments, particularly in strains associated with winemaking. These adaptations include modified gene content related to carbon and nitrogen source assimilation and increased fitness in the presence of ethanol and sulfites .

Nuclear proteins like NUR1 could potentially contribute to these adaptations through:

• Chromatin organization: Influencing the accessibility of genes relevant to stress response and metabolism.

• Transcriptional regulation: Potentially interacting with transcription factors or chromatin remodeling complexes that regulate genes involved in adaptation.

• Genome stability: Maintaining nuclear integrity under stressful conditions such as high ethanol concentrations.

• Environmental response sensing: Nuclear rim proteins can sometimes be involved in signaling pathways that detect environmental changes.

The evolutionary studies of L. thermotolerans have highlighted the role of geographic isolation and local adaptation as drivers of the evolutionary process in this species. Mitochondrial genomics and microsatellite studies have shown that geographic isolation and adaptation to local conditions have significantly shaped the genetic diversity of this species, which may extend to nuclear proteins like NUR1 .

How does NUR1 expression change under different fermentation conditions?

Under changing culture conditions, L. thermotolerans exhibits significant modifications in its expression profile, more pronounced than those observed in S. cerevisiae. The shift from aerobic to anaerobic conditions significantly influences carbohydrate metabolism and lipid biosynthesis in L. thermotolerans. When transitioning to anaerobic conditions, especially in mixed cultures, the most enriched processes relate to nutrient uptake, filamentous growth (as a response to starvation), and iron homeostasis .

While specific data on NUR1 expression changes are not detailed in the available research, nuclear proteins often play regulatory roles in these adaptive responses. Future research should investigate:

• Transcriptomic analysis of NUR1 expression under various fermentation conditions (temperature, pH, sugar concentration)

• Proteomic studies to quantify NUR1 protein levels and potential post-translational modifications

• Localization studies to determine if the subcellular distribution of NUR1 changes under different conditions

• Correlation of NUR1 expression with specific metabolic outputs, such as lactic acid production

What are the implications of NUR1 variants across different L. thermotolerans strains?

Recent whole-genome sequencing of 145 L. thermotolerans strains revealed six well-defined groups primarily delineated by ecological origin, with significant genetic diversity between them. Anthropized strains (those adapted to human-made environments like wineries) showed lower genetic diversity due to purifying selection in the winemaking environment .

This genomic diversity likely extends to nuclear proteins like NUR1, with potential implications for:

• Functional variation: Different variants might confer distinct advantages in specific ecological niches.

• Adaptation signatures: Comparing NUR1 sequences across strains might reveal signatures of selection that correlate with environmental adaptations.

• Structural differences: Amino acid substitutions could affect protein-protein interactions or subcellular localization.

• Regulatory variation: Differences in promoter regions could affect expression levels and patterns.

A comprehensive analysis of NUR1 variants would involve:

• Sequencing the NUR1 gene across diverse L. thermotolerans strains

• Correlating sequence variations with ecological origin and phenotypic traits

• Functional characterization of different variants through complementation studies

• Analysis of selection pressures on different regions of the protein

What methodologies can be used to study NUR1 interactions with the nuclear membrane?

As a nuclear rim protein, NUR1 likely interacts with components of the nuclear membrane and potentially with chromatin. Several advanced methodologies can be employed to characterize these interactions:

• Proximity labeling techniques: BioID or APEX2 fusions to NUR1 can identify proteins in close proximity in their native cellular environment.

• Super-resolution microscopy: Techniques such as STORM or PALM can provide detailed visualization of NUR1 localization relative to other nuclear envelope components with nanometer precision.

• FRET analysis: To detect direct protein-protein interactions at the nuclear envelope.

• Membrane fractionation: Biochemical isolation of nuclear envelope fractions followed by mass spectrometry to identify associated proteins.

• Cryo-electron tomography: For structural analysis of NUR1 in the context of the nuclear membrane.

• Split-GFP complementation: To validate specific protein-protein interactions in vivo.

How can CRISPR-Cas9 technology be applied to study NUR1 function in L. thermotolerans?

CRISPR-Cas9 technology offers powerful approaches for studying NUR1 function in L. thermotolerans:

• Gene knockout: Complete deletion of NUR1 to assess its essentiality and the resulting phenotypes.

• Domain analysis: Introduction of precise mutations or deletions to specific functional domains to determine their importance.

• Tagging: Integration of fluorescent or affinity tags at the endogenous locus for visualization or purification.

• CRISPRi/a: CRISPR interference or activation to modulate NUR1 expression without altering the gene sequence.

• Base or prime editing: Introduction of specific amino acid changes to study the effects of natural variants.

The implementation of CRISPR-Cas9 in L. thermotolerans requires optimization of:

• Delivery methods for Cas9 and guide RNAs

• Selection markers appropriate for this species

• Homology-directed repair templates

• Guide RNA design specific to the L. thermotolerans genome