pH homeostasis in yeast; the phosphate perspective

Abstract

Recent research further clarified the molecular mechanisms that link nutrient signaling and pH homeostasis with the regulation of growth and survival of the budding yeast Saccharomyces cerevisiae. The central nutrient signaling kinases PKA, TORC1, and Sch9 are intimately associated to pH homeostasis, presumably allowing them to concert far-reaching phenotypical repercussions of nutritional cues. To exemplify such repercussions, we briefly describe consequences for phosphate uptake and signaling and outline interactions between phosphate homeostasis and the players involved in intra- and extracellular pH control. Inorganic phosphate uptake, its subcellular distribution, and its conversion into polyphosphates are dependent on the proton gradients created over different membranes. Conversely, polyphosphate metabolism appears to contribute in determining the intracellular pH. Additionally, inositol pyrophosphates are emerging as potent determinants of growth potential, in this way providing feedback from phosphate metabolism onto the central nutrient signaling kinases. All these data point towards the importance of phosphate metabolism in the reciprocal regulation of nutrient signaling and pH homeostasis.

Identity and functions of inorganic and inositol polyphosphates in plants

“…Under Pi starvation, yeast cells can remobilize Pi from polyP (Shirahama et al, 1996). The vacuolar polyP store thus allows yeast cells to maintain Pi, ion (Rosenfeld et al, 2010) and pH (Eskes et al, 2018) homeostasis. PolyPs control the cell cycle by providing the Pi required for nucleotide synthesis during DNA replication (Bru et al, 2016).…”

pH homeostasis links the nutrient sensing PKA/TORC1/Sch9 ménage-à-trois to stress tolerance and longevity

“…The proton gradients established by the V-ATPase, Pma1 and other proton transport systems are of absolute importance for several processes. For instance, the driving force created by these gradients is crucial to maintain phosphate homeostasis 36 and the cation balance of alkali metals (Na + and K + ), divalent cations (Ca 2+ and Mg 2+ ) and trace metals (Fe 2+ , Zn 2+ , Cu 2+ and Mn 2+ ). Their symport/antiport along with H + helps to maintain their physiological and non-toxic levels, so as to provide a suitable environment for various biochemical reactions.…”

“…Several membrane proteins rely on the proton driving force. Examples are the proton-coupled phosphate symporters and the different amino acid permeases that reside in the plasma membrane 36 37 or the yeast AVT1-7 family members that mediate bidirectional transport of amino acids across the vacuolar membrane 38 .…”

Biotechnological synthesis of water‐soluble food‐grade polyphosphate with Saccharomyces cerevisiae

“…The polyP degradation in the vacuole is facilitated by S. cerevisiae endopolyphosphatase 1 and 2 (Gerasimaite & Mayer, 2016, 2017). P i that is generated in the vacuole is transported to the cytosol by Pho91 (Eskes, Deprez, Wilms, & Winderickx, 2018).…”