An evolutionarily conserved mechanism controls reversible amyloids of pyruvate kinase via pH-sensing regions

Amyloids are known as irreversible aggregates associated with neurodegenerative diseases. However, recent evidence shows that a subset of amyloids can form reversibly and fulfill essential cellular functions. Yet, the molecular mechanisms regulating functional amyloids and distinguishing them from pathological aggregates remain unclear. Here, we investigate the conserved principles of amyloid reversibility by studying the essential metabolic enzyme pyruvate kinase (PK) in yeast and human cells. We demonstrate that yeast PK (Cdc19) and human PK (PKM2) form reversible amyloids through a pH-sensitive amyloid core. Stress-induced cytosolic acidification promotes aggregation via protonation of specific glutamate (yeast) or histidine (human) residues within the amyloid core. Mutations mimicking protonation cause constitutive PK aggregation, while non-protonatable PK mutants remain soluble even upon stress. Physiological PK aggregation is coupled to metabolic rewiring and glycolysis arrest, causing severe growth defects when misregulated. Our work thus identifies an evolutionarily conserved, potentially widespread mechanism regulating functional amyloids during stress. [Display omitted] •Yeast and human pyruvate kinase (PK) form reversible amyloids upon stress•Reversible PK aggregation is regulated by a conserved pH-sensing amyloid core motif•Protonation of specific residues neutralizes the net charge of the amyloid core•Reversible PK aggregation is linked to profound changes in cellular metabolism Cereghetti et al. identify an evolutionarily conserved mechanism that regulates the formation and disassembly of functional pyruvate kinase amyloids in response to cellular stress. This physiological process is controlled by cytosolic pH changes and significantly impacts cellular metabolism and growth.