The Toxic Effects of Ppz1 Overexpression Involve Nha1-Mediated Deregulation of K<sup>+</sup> and H<sup>+</sup> Homeostasis

Marcel Albacar, Lenka Sacka, Carlos Calafí, Diego Veláquez, Antonio Casamayor, Joaquin Arino, Olga Zimmermannova

Research output: Contribution to journalArticleResearchpeer-review

2 Citations (Scopus)

Abstract

The alteration of the fine-tuned balance of phospho/dephosphorylation reactions in the cell often results in functional disturbance. In the yeast Saccharomyces cerevisiae, the overexpression of Ser/Thr phosphatase Ppz1 drastically blocks cell proliferation, with a profound change in the transcriptomic and phosphoproteomic profiles. While the deleterious effect on growth likely derives from the alteration of multiple targets, the precise mechanisms are still obscure. Ppz1 is a negative effector of potassium influx. However, we show that the toxic effect of Ppz1 overexpression is unrelated to the Trk1/2 high-affinity potassium importers. Cells overexpressing Ppz1 exhibit decreased K+ content, increased cytosolic acidification, and fail to properly acidify the medium. These effects, as well as the growth defect, are counteracted by the deletion of NHA1 gene, which encodes a plasma membrane Na+, K+/H+ antiporter. The beneficial effect of a lack of Nha1 on the growth vanishes as the pH of the medium approaches neutrality, is not eliminated by the expression of two non-functional Nha1 variants (D145N or D177N), and is exacerbated by a hyperactive Nha1 version (S481A). All our results show that high levels of Ppz1 overactivate Nha1, leading to an excessive entry of H+ and efflux of K+, which is detrimental for growth.
Original languageEnglish
JournalJournal of Fungi
Volume7
Issue number12
DOIs
Publication statusPublished - 25 Nov 2021

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