Newly discovered protein could be used to produce life-saving antifungals

Like bacteria, yeasts are found everywhere, even in and around our bodies. And, as with bacteria, you can become infected by yeasts and become ill. Yeasts infect about 150 million people a year and kill about 1.7 million, especially those who are immunocompromised.

Yeast cells and human immune system cells rely on surprisingly similar chemical reactions to know when to grow. University of Arizona scientists have identified subtle differences between the two cell types that could help spur the development of antifungal drugs that are able to attack disease-causing yeasts in the body while sparing the immune system.

Their findings, published in the journal eLife, not only have implications for drug development, they also provide important insight into the evolution of an ancient growth control pathway found in all multicellular organisms.

It is well known in the scientific community that a conglomerate of proteins called TORC1 — short for Target of Rapamycin kinase Complex 1 — controls the growth of cells in everything from humans to yeasts. But researchers have now identified and named the protein that triggers this process in yeasts — a nutrient sensor and TORC1 regulator they named Ait1. When working normally, Ait1 shuts down TORC1 in yeasts when cells are starved for nutrients, blocking cell growth.

“Ait1 is kind oflike a hand holding TORC1 in place, with a finger that reaches over the top and flicks TORC1 on and off depending on how many nutrients a cell has,” said study co-author Andrew Capaldi, an associate professor in the UArizona Department of Molecular and Cellular Biology and BIO5 Institute member.

The Capaldi Lab is interested in determining how cells sense stress and starvation and then decide how fast to grow. Understanding how TORC1 is triggered in different organisms is important for developing treatments for a wide variety of diseases.

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