What can stressed yeast teach us about fundamental processes in the cell? A lot, according to scientists at the European Molecular Biology Laboratory (EMBL). The team studies, among other topics, how cells adapt to stress -- such as nutrient deprivation. One of their favourite test subjects is the yeast species S.
pombe, for centuries used in traditional brewing. As a eukaryote, it's in many ways similar to human cells, so biologists often use it as model organism to study fundamental cellular processes. Ribosomes turn upside-down in hungry cells Scientists have observed that yeast cells have a remarkable adaptation to starvation: their mitochondria get coated by a swarm of massive molecular complexes called ribosomes.
Intrigued by this odd phenomenon, the Mattei Team at EMBL Heidelberg and the Jomaa Lab at the University of Virginia School of Medicine explored it in greater detail using single-particle cryo-electron microscopy and cryo-electron tomography. Ribosomes are the cell's heavyweight molecular machinery that produces proteins. It turned out, however, that in hungry yeast cells, the ribosomes that crowd on the surface of the mitochondria don't produce anything.
They are hibernating. "One way for a cell to survive stressful conditions until better days is to reduce its use of energy to a minimum," explained Olivier Gemin, EIPOD Postdoctoral Fellow in the Mattei Team who led this new study. "Producing proteins demands a lot of energy, which can be saved by blocking rib.