How Microorganisms Signal Food Shortages

To grow and survive, tiny organisms like yeast must sometimes adapt their nutrient sources to changes in their environment. FMI researchers have discovered that yeast cells communicate with each other to use less favorable nutrients if they anticipate a shortage of their preferred 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, yeast have their favorite nutrients. To study what happens when yeast cells anticipate a shortage of their favorite food, Shin Ohsawa, a postdoctoral fellow 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 key components of the mechanism yeast cells use to communicate. However, the researchers didn’t know how these molecules prompted yeast cells to switch to less favorable food sources, Ohsawa says. He and his colleagues found that increasing NSF levels led to changes in the yeast cells’ gene expression program, prompting them to switch to alternative nutrient sources.

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

The results reveal a key communication mechanism that allows yeast cells to be economical with food. Growth and survival strategies are conserved across species, and yeast has served as a wonderful model organism, Bühler says.

“The study of yeast has allowed us to acquire important knowledge about cell biology and the regulation of gene expression,” he explains. “Beyond fundamental knowledge, a deep understanding of yeast metabolism becomes particularly relevant in pathogenic situations.”