Extracellular Ca(2+) sensing contributes to excess Ca(2+) accumulation and vacuolar fragmentation in a pmr1Delta mutant of S. cerevisiae.

Academic Article

Abstract

  • Previous studies have suggested that yeast strains lacking the Ca(2+)-ATPase Pmr1p are unable to maintain an adequate level of Ca(2+) within the Golgi apparatus. It is thought that this compartmental store depletion induces a signal that causes an increased rate of Ca(2+) uptake and accumulation in a manner similar to the capacitative Ca(2+) entry (CCE) response in non-excitable mammalian cells. To explore this model further, we examined cellular Ca(2+) uptake and accumulation in a pmr1Delta strain grown in the presence of a reduced level of divalent cations. We found that the level of Ca(2+) uptake and accumulation in a pmr1Delta strain increased as the concentration of divalent cations in the growth medium decreased. These results are inconsistent with a model in which cellular Ca(2+) uptake and accumulation are determined solely by the depletion of Ca(2+) in an intracellular compartment. Instead, our results suggest that a second regulatory mechanism couples cellular Ca(2+) uptake to the availability of Ca(2+) in the extracellular environment. Furthermore, we found that various conditions that increase the level of cytosolic Ca(2+) correlate with vacuolar fragmentation in wild-type (WT), pmr1Delta and pmr1Delta/pmc1Delta yeast strains. This suggests that vacuolar fragmentation might function as a normal physiological response to Ca(2+) stress that increases the vacuolar surface/volume ratio, thereby maximizing the sequestration of this important signaling molecule.
  • Published In

    Keywords

  • Blotting, Northern, Calcium, Calcium-Transporting ATPases, Dose-Response Relationship, Drug, Gene Expression Regulation, Enzymologic, Gene Expression Regulation, Fungal, Golgi Apparatus, Homeostasis, Models, Biological, Molecular Chaperones, Mutation, RNA, Messenger, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Vacuoles
  • Digital Object Identifier (doi)

    Pubmed Id

  • 6248202
  • Author List

  • Kellermayer R; Aiello DP; Miseta A; Bedwell DM
  • Start Page

  • 1637
  • End Page

  • 1646
  • Volume

  • 116
  • Issue

  • Pt 8