A novel role for the yeast protein kinase Dbf2p in vacuolar H+-ATPase function and sorbic acid stress tolerance.
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 (dbf2Delta). Crucially, VMA2 is a multicopy suppressor of both the sorbic acid-sensitive phenotype and the impaired vacuolar-acidification defect of dbf2Delta 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.
Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
Vasso
V
Makrantoni
Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
Paul
P
Dennison
Division of Gene Regulation and Expression, College of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
Michael J R
MJR
Stark
Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
Peter J
PJ
Coote
D000222:Adaptation, Physiological; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D018869:Heat-Shock Response; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013011:Sorbic Acid / Q000494:pharmacology*; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C085768:DBF2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D025262:Vacuolar Proton-Translocating ATPases; D013011:Sorbic Acid