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Zhang C, Feng Y, Balutowski A, Miner GE, Rivera-Kohr DA, Hrabak MR, Sullivan KD, Guo A, Calderin JD, Fratti RA. The interdependent transport of yeast vacuole Ca 2+ and H + and the role of phosphatidylinositol 3,5-bisphosphate. J Biol Chem 2022; 298:102672. [PMID: 36334632 PMCID: PMC9706634 DOI: 10.1016/j.jbc.2022.102672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/27/2022] Open
Abstract
Yeast vacuoles are acidified by the v-type H+-ATPase (V-ATPase) that is comprised of the membrane embedded VO complex and the soluble cytoplasmic V1 complex. The assembly of the V1-VO holoenzyme on the vacuole is stabilized in part through interactions between the VO a-subunit ortholog Vph1 and the lipid phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2). PI(3,5)P2 also affects vacuolar Ca2+ release through the channel Yvc1 and uptake through the Ca2+ pump Pmc1. Here, we asked if H+ and Ca2+ transport activities were connected through PI(3,5)P2. We found that overproduction of PI(3,5)P2 by the hyperactive fab1T2250A mutant augmented vacuole acidification, whereas the kinase-inactive fab1EEE mutant attenuated the formation of a H+ gradient. Separately, we tested the effects of excess Ca2+ on vacuole acidification. Adding micromolar Ca2+ blocked vacuole acidification, whereas chelating Ca2+ accelerated acidification. The effect of adding Ca2+ on acidification was eliminated when the Ca2+/H+ antiporter Vcx1 was absent, indicating that the vacuolar H+ gradient can collapse during Ca2+ stress through Vcx1 activity. This, however, was independent of PI(3,5)P2, suggesting that PI(3,5)P2 plays a role in submicromolar Ca2+ flux but not under Ca2+ shock. To see if the link between Ca2+ and H+ transport was bidirectional, we examined Ca2+ transport when vacuole acidification was inhibited. We found that Ca2+ transport was inhibited by halting V-ATPase activity with Bafilomycin or neutralizing vacuolar pH with chloroquine. Together, these data show that Ca2+ transport and V-ATPase efficacy are connected but not necessarily through PI(3,5)P2.
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Affiliation(s)
- Chi Zhang
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Yilin Feng
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Adam Balutowski
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Gregory E Miner
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - David A Rivera-Kohr
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Michael R Hrabak
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Katherine D Sullivan
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Annie Guo
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Jorge D Calderin
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Rutilio A Fratti
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois, USA; Center for Biophysics & Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA.
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