Indian Institute of Science, Bengaluru
Researchers at the Department of Biochemistry, Indian Institute of Science, have developed a novel method for the production of recombinant proteins.
According to IISc, mass production of recombinant proteins using yeast cell factories needs methanol, a compound that requires safe handling, carries the risk of catching fire, and sometimes produces harmful byproducts. However, researchers have now developed an alternative, safer process that instead relies on a common food additive called monosodium glutamate (MSG).
Recombinant proteins, such as vaccine antigens, insulin and monoclonal antibodies, are mass-produced by growing modified bacterial, viral or mammalian cells in large bioreactors. The most widely used organism is the yeast Pichia pastoris (now called Komagataella phaffii).
A unique promoter
“It contains a unique promoter – a specific gene region which can be activated by methanol. This promoter codes for an enzyme called alcohol oxidase (AOX),” IISc said.
To mass-produce a recombinant protein, the gene coding for that protein is spliced into the yeast genome right next to the AOX promoter. The yeast cells are then fed glycerol or glucose as the carbon source. Once enough cells have formed, methanol is added, which activates the AOX promoter, and the cells start producing the recombinant protein in copious amounts.
“Most industries use this methanol-induced process for producing recombinant proteins. However, methanol is highly flammable and hazardous, requiring stringent safety precautions. Methanol is also metabolized to form hydrogen peroxide which can induce oxidative stress in the yeast cells or damage the recombinant proteins,” said Prof P.N. Rangarajan, corresponding author of the study published in Microbial Cell Factories.
Role of MSG
To solve this problem, Trishna Dey, a former PhD student at the Department of Biochemistry, started looking for alternatives. After an extensive search, the team found that monosodium glutamate (MSG), a USFDA-approved food additive, can activate a different promoter in the yeast genome that codes for an enzyme called phosphoenolpyruvate carboxykinase (PEPCK). Activating this promoter with MSG led to protein production similar to methanol activation of the AOX promoter.
The researchers hope that this novel and indigenous expression system can be used in biotech industries to mass-produce valuable proteins, including milk and egg proteins, baby food supplements, and nutraceuticals, as well as therapeutic molecules.
