New Low Temperature System for Enhanced Gene Expression in Yeast

Jenn Hoskins
30th May, 2024

New Low Temperature System for Enhanced Gene Expression in Yeast

Image Source: Natural Science News, 2024

Key Findings

  • The study by the ARC Centre of Excellence in Synthetic Biology developed a new genetic system called LowTempGAL in yeast to control gene expression using temperature changes
  • The LowTempGAL system uses temperature biosensors to regulate gene expression but initially had issues with responsiveness and precision
  • Researchers improved the system by adding a second control layer and optimizing components, resulting in rapid and precise gene expression changes with temperature shifts
Temperature is a crucial factor in the biomanufacturing of biologics, which are products derived from living organisms. A recent study conducted by the ARC Centre of Excellence in Synthetic Biology has explored a novel low temperature-inducible genetic system (LowTempGAL) in the model yeast Saccharomyces cerevisiae[1]. This research aims to address some of the limitations in precision fermentation by developing a highly responsive system for controlling gene expression based on temperature changes. In the context of metabolic engineering, the ability to control gene expression dynamically is essential for optimizing the production of valuable chemicals. Dynamic metabolic engineering involves designing genetic systems that allow cells to adjust their metabolic flux in response to internal and external conditions[2]. This new study builds on this concept by introducing temperature as a control mechanism. The LowTempGAL system utilizes two temperature biosensors: a heat-inducible degron and a heat-inducible protein aggregation domain. These biosensors regulate the GAL activator Gal4p, which is crucial for controlling gene expression in yeast. However, the initial system exhibited some "leakiness," meaning that it was not entirely responsive to temperature changes. To achieve a more precise control, the researchers implemented a Boolean-type induction mechanism. This involved adding a second layer of control through low-temperature-mediated repression of the GAL repressor gene GAL80. Despite these improvements, the system still faced challenges such as delayed response to low-temperature triggers and weak response at 30°C. To overcome these issues, the researchers conducted proteomics analysis, which suggested that residual Gal80p and insufficient Gal4p were causing suboptimal induction. They then engineered 'Turbo' mechanisms by incorporating basal Gal4p expression and a galactose-independent Gal80p-suppressing Gal3p mutant (Gal3Cp). By varying the configurations of Gal3Cp, the LowTempGAL systems were optimized to achieve rapid and stringent high-level induction when the temperature shifted from a high range (37-33°C) to a low range (≤30°C). This study is significant because it provides a synthetic biology approach to deploying highly responsive genetic circuits using 'leaky' biosensors. The key to their success lies in optimizing the intricate layout of this multi-factor system. The LowTempGAL systems have the potential to be applied in non-conventional yeast platforms, thereby enhancing precision biomanufacturing. The findings from this study are not isolated but build on previous advancements in synthetic biology and metabolic engineering. For instance, the use of orthogonal systems for heterologous protein expression, which depend on synthetic transcription factors (synTFs) and corresponding small synthetic promoters (synPs), has been shown to provide a broad spectrum of expression strengths[3]. This flexibility is crucial for balancing expression levels within heterologous pathways, a concept that aligns well with the goals of the LowTempGAL system. Moreover, the development of programmable genetic circuits, as facilitated by tools like the Cello software, has revolutionized the design of synthetic biological systems[4]. Cello enables the automatic design of DNA sequences for programmable circuits based on high-level software descriptions and a library of characterized DNA parts. This approach allows for modular design and formalized circuit transformations, which are essential for creating complex genetic systems like the LowTempGAL. In summary, the LowTempGAL system represents a significant advancement in the field of synthetic biology and metabolic engineering. By leveraging temperature as a control mechanism, the researchers have developed a highly responsive genetic system that can be fine-tuned for various applications in precision biomanufacturing. This study not only builds on previous research but also opens new avenues for optimizing the production of valuable chemicals using microbial organisms.

BiotechGeneticsBiochem

References

Main Study

1) LowTempGAL: a highly responsive low temperature-inducible GAL system in Saccharomyces cerevisiae.

Published 29th May, 2024

https://doi.org/10.1093/nar/gkae460

Related Studies

2) Dynamic control in metabolic engineering: Theories, tools, and applications.

https://doi.org/10.1016/j.ymben.2020.08.015

3) Synthetic Promoters and Transcription Factors for Heterologous Protein Expression in Saccharomyces cerevisiae.

https://doi.org/10.3389/fbioe.2017.00063

4) Genetic circuit design automation with Cello 2.0.

https://doi.org/10.1038/s41596-021-00675-2


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