A novel role for the yeast protein kinase Dbf2p in vacuolar H+-ATPase function and sorbic acid stress tolerance Makrantoni, Vasso and Dennison, Paul and Stark, Michael J. R. and Coote, Peter J.,, 153, 4016-4026 (2007), doi = https://doi.org/10.1099/mic.0.2007/010298-0, publicationName = Microbiology Society, issn = 1350-0872, abstract= In Saccharomyces cerevisiae, the serine-threonine protein kinase activity of Dbf2p is required for tolerance to the weak organic acid sorbic acid. Here we show that Dbf2p is required for normal phosphorylation of the vacuolar H+-ATPase (V-ATPase) A and B subunits Vma1p and Vma2p. Loss of V-ATPase activity due to bafilomycin treatment or deletion of either VMA1 or VMA2 resulted in sorbic acid hypersensitivity and impaired vacuolar acidification, phenotypes also observed in both a kinase-inactive dbf2 mutant and cells completely lacking DBF2 (dbf2Δ). Crucially, VMA2 is a multicopy suppressor of both the sorbic acid-sensitive phenotype and the impaired vacuolar-acidification defect of dbf2Δ cells, confirming a functional interaction between Dbf2p and Vma2p. The yeast V-ATPase is therefore involved in mediating sorbic acid stress tolerance, and we have shown a novel and unexpected role for the cell cycle-regulated protein kinase Dbf2p in promoting V-ATPase function., language=, type=