title: Glutathione depletion activates the yeast vacuolar transient receptor potential channel, Yvc1p, by reversible glutathionylation of specific cysteines.
abstract: Glutathione depletion and calcium influx into the cytoplasm are two hallmarks of apoptosis. We have been investigating how glutathione depletion leads to apoptosis in yeast. We show here that glutathione depletion in yeast leads to the activation of two cytoplasmically inward-facing channels: the plasma membrane, Cch1p, and the vacuolar calcium channel, Yvc1p. Deletion of these channels partially rescues cells from glutathione depletion-induced cell death. Subsequent investigations on the Yvc1p channel, a homologue of the mammalian TRP channels, revealed that the channel is activated by glutathionylation. Yvc1p has nine cysteine residues, of which eight are located in the cytoplasmic regions and one on the transmembrane domain. We show that three of these cysteines, Cys-17, Cys-79, and Cys-191, are specifically glutathionylated. Mutation of these cysteines to alanine leads to a loss in glutathionylation and a concomitant loss in calcium channel activity. We further investigated the mechanism of glutathionylation and demonstrate a role for the yeast glutathione S-transferase Gtt1p in glutathionylation. Yvc1p is also deglutathionylated, and this was found to be mediated by the yeast thioredoxin, Trx2p. A model for redox activation and deactivation of the yeast Yvc1p channel is presented.
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali 140306, Punjab, India.
authors.forename: Avinash
authors.initials: A
authors.lastname: Chandel
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali 140306, Punjab, India.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Das
authors.affiliation: Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali 140306, Punjab, India anand@iisermohali.ac.in anand.bachhawat@gmail.com.
authors.forename: Anand K
authors.initials: AK
authors.lastname: Bachhawat
mesh_terms: D017209:Apoptosis; D015220:Calcium Channels / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D005978:Glutathione; D005982:Glutathione Transferase; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D050052:TRPC Cation Channels / Q000235:genetics* / Q000378:metabolism*; D050051:Transient Receptor Potential Channels / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism
chemical_list: C108765:CCH1 protein, S cerevisiae; D015220:Calcium Channels; D029701:Saccharomyces cerevisiae Proteins; D050052:TRPC Cation Channels; D050051:Transient Receptor Potential Channels; C446509:Yvc1 protein, S cerevisiae; D005982:Glutathione Transferase; D005978:Glutathione; D003545:Cysteine