How microorganisms communicate food shortages

To grow and survive, tiny organisms such as yeast must sometimes adapt their nutrient sources in response to changes in the environment. FMI researchers have now found that yeast cells communicate with each other to use less favorable nutrients if they foresee a shortage of their favorite food. This communication is facilitated by secreted molecules that interact with a protein in mitochondria, the cells’ energy factories.

The findings reveal a crucial mechanism that allows microorganisms to choose the right menu. The research is published in The EMBO Journal.

Like humans, yeasts have their favorite nutrients. To investigate what happens when yeast cells anticipate a shortage of their favorite food, Shin Ohsawa—a postdoc in the Bühler lab—and his collaborators at the RIKEN Center for Sustainable Resource Science and the University of Tokyo in Japan studied the fission yeast Schizosaccharomyces pombe.

Previous research by the RIKEN team had identified specific molecules called Nitrogen Signaling Factors (NSFs) as essential components of the mechanism that yeast cells use to communicate. However, the researchers didn’t know how these molecules sway yeast cells to turn to less favorable food sources, Ohsawa says. He and his colleagues discovered that increasing NSFs levels lead to changes in the gene expression program of yeast cells, prompting them to switch to alternative nutrient sources.

Using chemically modified molecules to capture the interactions between NSFs and yeast proteins, the researchers found that NSFs interact directly with a mitochondrial protein involved in metabolism, maximizing growth in response to an imminent change in nutrient availability.

The findings unveil a key communication mechanism that allows yeast cells to be frugal with food. Strategies for growth and survival are conserved across species, and yeast has served as a tremendous model organism, Bühler says.

“We gained significant insights into cell biology and gene expression regulation through studying yeast,” he says. “Beyond fundamental knowledge, a thorough understanding of yeast metabolism becomes particularly relevant in pathogenic situations.”