Red light can control bacterial genes

Researchers have developed a technique in which bacterial gene expression is controlled using red light. The technique can be utilised, for example, in the production of pharmaceutical proteins.

Researchers have developed a new way to regulate gene expression of E. coli bacteria by employing red light. The optogenetic pREDusk tools, developed by researchers at the University of Helsinki, the University of Jyväskylä, and the University of Bayreuth, can stop or initiate gene expression in bacteria with red light.

“The task of genes is to instruct cells to produce molecules, such as proteins. Cells contain countless variety of proteins, which affect, among other things, cell metabolism. The ability to control gene expression with light provides a new tool for investigating these phenomena,” says Doctoral Researcher Elina Multamäki from the Department of Anatomy, University of Helsinki.

A previous study demonstrated how a red-light–sensing photoreceptor protein known as phytochrome functions. The researchers had also noticed that the light-sensing part of the phytochrome can be used to control the functioning of other proteins. The pREDusk tools were developed on the basis of these earlier findings.

“By using a fluorescent marker protein, we were able to assess that the control of protein production was successful in both 100-millilitre liquid cultures and at the level of individual bacterial cells,” Multamäki says.

Light controls protein production

The optogenetic pREDusk tools can be used, for example, to control the protein production in bacterial cells. There are target applications in both biotechnology and patient care.

For years, E. coli bacteria have been used in the production of insulin and other pharmaceutical proteins. According to Multamäki, light would make bacterial cells produce proteins increasingly efficiently. At the same time, using light would replace chemical compounds that regulate protein production.

“Chemical compounds are difficult, since they can no longer be removed once they have been added to the mix. In contrast, light intensity can be freely varied at different stages of protein production,” Multamäki says.

One target for application may be found in the gut.

“Disturbances in the gut microbiota have proven to be a significant factor in many diseases, such as Crohn’s disease and type 2 diabetes. Since red light penetrates deep into mammalian tissues, we could also control bacterial protein production in intestines.”

The study was published in August 2022 in the ACS Synthetic Biology journal. It is part of the joint research in the field of optogenetics carried out by research groups headed by Dr Heikki Takala, (University of Helsinki and University of Jyväskylä), and Professor Andreas Möglich (University of Bayreuth).