The Reduced Level of Inorganic Polyphosphate Mobilizes Antioxidant and Manganese-Resistance Systems in Saccharomyces cerevisiae

Abstract

Inorganic polyphosphate (polyP) is crucial for adaptive reactions and stress response in microorganisms. A convenient model to study the role of polyP in yeast is the Saccharomyces cerevisiae strain CRN/PPN1 that overexpresses polyphosphatase Ppn1 with stably decreased polyphosphate level. In this study, we combined the whole-transcriptome sequencing, fluorescence microscopy, and polyP quantification to characterize the CRN/PPN1 response to manganese and oxidative stresses. CRN/PPN1 exhibits enhanced resistance to manganese and peroxide due to its pre-adaptive state observed in normal conditions. The pre-adaptive state is characterized by up-regulated genes involved in response to an external stimulus, plasma membrane organization, and oxidation/reduction. The transcriptome-wide data allowed the identification of particular genes crucial for overcoming the manganese excess. The key gene responsible for manganese resistance is PHO84 encoding a low-affinity manganese transporter: Strong PHO84 down-regulation in CRN/PPN1 increases manganese resistance by reduced manganese uptake. On the contrary, PHM7, the top up-regulated gene in CRN/PPN1, is also strongly up-regulated in the manganese-adapted parent strain. Phm7 is an unannotated protein, but manganese adaptation is significantly impaired in Δphm7, thus suggesting its essential function in manganese or phosphate transport.

Mössbauer and LC-ICP-MS investigation of iron trafficking between vacuoles and mitochondria in vma2Δ Saccharomyces cerevisiae

“…vma2Δ W cells and cytosol contained less Mn than in WT cells and cytosol; a similar decline has been observed in PPN1-UP cells ( 47 ) which have elevated levels of the polyphosphatase Ppn1. In both strains, cells contain low levels of polyphosphate relative to WT.…”

VTC4 Polyphosphate Polymerase Knockout Increases Stress Resistance of Saccharomyces cerevisiae Cells

“…The resistance to manganese and peroxide stresses observed in the Δvtc4 strain was also observed for the Ppn1-overexpressing CRN/PPN1 strain, which also had decreased polyP level [14]. The CRN/PPN1 strain showed constitutively higher expression of genes associated with response to external stimulus, plasma membrane organization, and oxidation/reduction.…”

“…The high-affinity phosphate transporter Pho84 of S. cerevisiae is involved in the uptake of both Pi and divalent metal ions [59,60]. Therefore, we expected a decrease in the magnesium-stimulated accumulation of phosphate by the cells of both strains with decreased PHO84 expression, СRN/PPN1 [14] and Δvtc4.…”

“…Biology 2021, 10, 487 2 of 13 In yeast, polyPs are involved in the control of the cell cycle [12], stress response [13][14][15], and virulence [16]. Yeast genomes do not contain orthologs of bacterial polyphosphate kinases, and polyP synthesis is performed by the Vtc4 protein [17].…”

Vtc5 is localized to the vacuole membrane by the conserved AP-3 complex to regulate polyphosphate synthesis in budding yeast

“…In addition to being the only known polyP synthetase in yeast, the VTC complex has been demonstrated or suggested to play a role in a myriad of cellular activities such as the stability of vacuolar V-ATPase subunits, in vacuole fusion, and in microautophagy [15][16][17] . PolyP itself has also been implicated in the regulation of pH balance 18 , ion homeostasis [19][20][21] , and phosphate metabolism 18,[22][23][24] .…”