Vacuolar Cation/H+ Antiporters of Saccharomyces cerevisiae

We previously demonstrated that Saccharomyces cerevisiae vnx1Δ mutant strains displayed an almost total loss of Na+ and K+/H+ antiporter activity in a vacuole-enriched fraction. However, using different in vitro transport conditions, we were able to reveal additional K+/H+ antiporter activity. By di...

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Bibliographic Details
Published in:The Journal of biological chemistry 2010-10, Vol.285 (44), p.33914-33922
Main Authors: Cagnac, Olivier, Aranda-Sicilia, Maria Nieves, Leterrier, Marina, Rodriguez-Rosales, Maria-Pilar, Venema, Kees
Format: Article
Language:English
Subjects:
Antiporters - chemistry
Cadmium - chemistry
Cations - chemistry
Cinnamates - chemistry
Exchangers
Hygromycin B - analogs & derivatives
Hygromycin B - chemistry
Ion Homeostasis
Membrane Biology
Membrane Isolation
Microscopy, Fluorescence - methods
Mutant
Mutation
Plasmids - metabolism
Point Mutation
Potassium - chemistry
Potassium Transport
Saccharomyces cerevisiae
Saccharomyces cerevisiae - metabolism
Saccharomyces cerevisiae Proteins - chemistry
Sodium-Hydrogen Exchangers - chemistry
Subcellular Fractions - chemistry
Vacuolar Membrane
Vacuoles - metabolism
Yeast
Zinc - chemistry
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Summary:We previously demonstrated that Saccharomyces cerevisiae vnx1Δ mutant strains displayed an almost total loss of Na+ and K+/H+ antiporter activity in a vacuole-enriched fraction. However, using different in vitro transport conditions, we were able to reveal additional K+/H+ antiporter activity. By disrupting genes encoding transporters potentially involved in the vnx1 mutant strain, we determined that Vcx1p is responsible for this activity. This result was further confirmed by complementation of the vnx1Δvcx1Δ nhx1Δ triple mutant with Vcx1p and its inactivated mutant Vcx1p-H303A. Like the Ca2+/H+ antiporter activity catalyzed by Vcx1p, the K+/H+ antiporter activity was strongly inhibited by Cd2+ and to a lesser extend by Zn2+. Unlike as previously observed for NHX1 or VNX1, VCX1 overexpression only marginally improved the growth of yeast strain AXT3 in the presence of high concentrations of K+ and had no effect on hygromycin sensitivity. Subcellular localization showed that Vcx1p and Vnx1p are targeted to the vacuolar membrane, whereas Nhx1p is targeted to prevacuoles. The relative importance of Nhx1p, Vnx1p, and Vcx1p in the vacuolar accumulation of monovalent cations will be discussed.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M110.116590