Article

Cells respond to their environment. For example, when the unicellular budding yeast is short of nutrients, its cytoplasm becomes acidic. The functional role of this pH change has not been understood so far. The lab of Simon Alberti at the MPI-CBG now shows that low pH triggers the assembly of the key metabolic enzyme glutamine synthetase (Gln1) into thin elongated protein structures, so called filaments. The researchers further show that filament formation causes enzymatic inactivation and that the enzymes contained in filaments can be recycled when yeast resume normal growth.

Other metabolic enzymes also assemble into filaments at low pH. This suggests that filament formation may be a general mechanism to shut down the metabolism of a cell when nutrients are scarce. These findings may also explain how cells and organisms enter into states of suspended animation, such as dormancy or quiescence.