#Singapore #NUS #Synthetic Biology #Baker's Yeast

Breakthrough in Yeast Engineering by NUS Researchers

Researchers at the National University of Singapore (NUS) have made significant strides in biotechnology with their latest development: a baker’s yeast capable of sensing and responding to various colors of light. This advancement allows for greater control over cellular behavior using red and blue light. Baker's yeast, a key microorganism used in baking and brewing, has recently found applications in synthetic biology, extending its use to convert sugars into medicines, fuels, and industrial chemicals.

However, harnessing these engineered yeast cells effectively has posed challenges in achieving precise control rapidly and efficiently. To address this, the NUS team, led by Associate Professor POH Chueh-Loo from the Department of Biomedical Engineering, employed a technique known as optogenetics. This method creates a biological system where specific genes can be activated or deactivated in response to light signals.

By implementing this technology, the researchers were able to demonstrate that they could dynamically deliver biological instructions through different colors and patterns of light, thus eliminating the need for repetitive applications of chemical inducers. As Associate Professor Poh emphasized, “Achieving precise, dynamic control over cellular machinery has been a goal in synthetic biology.” This research represents a significant leap toward making biological manufacturing more predictable and programmable.

Development of Y-iLight: A Novel Tool for Yeast

Previously, yeast had been engineered to respond to single colors of light; however, this is the first instance of a strain capable of responding to multiple colors. One of the key challenges in this endeavor was to ensure reliability in response to red light. Earlier optogenetic systems needed multiple gene insertions or other factors to function effectively, which created obstacles for integration with other light-based systems.

To overcome this, the NUS team adapted a light-sensitive tool that had been successful in bacterial and mammalian systems, resulting in the creation of the y-iLight protein, specifically responsive to red light. When yeast is exposed to red light, y-iLight binds to specific DNA sequences, activating targeted genes. Importantly, this system operates without requiring additional chemicals beyond what is inherently found in yeast, enhancing its practicality for real-world applications.

Addressing Crosstalk Between Light Responses

Although y-iLight represents a breakthrough, it initially had a drawback where blue light could also trigger it. This overlap limited the independent operation of the red light system alongside the already established blue light system. The researchers tackled this issue creatively by employing a modular protein-engineering approach to develop y-iLight in a way that blocks its activity specifically under blue light conditions. The end result was successful independent control of two gene-expression channels within the same yeast strain, marking a key advancement in multiplexed optogenetics.

PhD student Linus TAN Yu-Han noted, “Achieving independent control without interference between the two systems was a significant challenge in yeast.” The team’s success paves the way for more intricate genetic programming possibilities, harnessing color light cues.

Multipurpose Applications of the Dual-Channel Optogenetic Strain

With their improved dual-channel optogenetic yeast, the researchers investigated how they could use multicolored light to control more sophisticated biological processes. They managed to link two enzymes required for synthesizing luteolin, a natural plant chemical, to independent red and blue light signals. By manipulating the timing and intensity of these light inputs, the researchers could fine-tune the yeast’s production of luteolin.

Moreover, the capacity to control yeast cell behavior through light is also notable. The team linked the FLO1 gene, which regulates cell clumping, to a red light-activated switch. When the yeast was exposed to red light, it triggered the cells to aggregate and settle, demonstrating how light can regulate both production and separation effectively.

Creating Living Images: A Technicolor Future for Yeast

Optogenetics also allows for spatial gene control, enabling genes to be activated only where light is focused. The NUS team applied this concept, programming yeast to generate differently colored compounds in response to red and blue lights. By spreading these yeast cells thinly on agar and projecting light through masks, they succeeded in creating patterned, multicolored designs termed “living images.”

Associate Professor Poh explained, “Together, this work illustrates that yeast can be controlled using various colors of light to regulate gene expression, metabolic pathways, and even spatial patterns.” Such advancements could greatly influence future biomanufacturing processes, optimizing pathways, and contributing to innovative living materials.

Future Prospects of Yeast Research at NUS

Currently, Associate Professor Poh and his laboratory are focusing on utilizing selectively designed gene networks to enhance these light-sensing proteins' effectiveness. In enhancing their strength and sensitivity, they aim to unlock new potentials for microbial applications in producing valuable chemicals and materials. The extensive possibilities from this research underscore the transformative impact of optogenetics in modern biotechnology and synthetic biology.

For more details, visit NUS News.