Metabolic control of acclimation to nutrient deprivation dependent on polyphosphate synthesis

Abstract

Polyphosphate, an energy-rich polymer conserved in all kingdoms of life, is integral to many cellular stress re-sponses, including nutrient deprivation, and yet, the mechanisms that underlie its biological roles are not wellunderstood. In this work, we elucidate the physiological function of this polymer in the acclimation of the modelalga Chlamydomonas reinhardtii to nutrient deprivation. Our data reveal that polyphosphate synthesis is vital tocontrol cellular adenosine 5′-triphosphate homeostasis and maintain both respiratory and photosynthetic elec-tron transport upon sulfur deprivation. Using both genetic and pharmacological approaches, we show that elec-tron flow in the energy-generating organelles is essential to induce and sustain acclimation to sulfur deprivationat the transcriptional level. These previously unidentified links among polyphosphate synthesis, photosyntheticand respiratory electron flow, and the acclimation of cells to nutrient deprivation could unveil the mechanism bywhich polyphosphate helps organisms cope with a myriad of stress conditions in a fluctuating environment.