The Golgi apparatus plays a significant role in the maintenance of Ca2+ homeostasis in the vps33Delta vacuolar biogenesis mutant of Saccharomyces cerevisiae

J Biol Chem. 1999 Feb 26;274(9):5939-47. doi: 10.1074/jbc.274.9.5939.

Abstract

The vacuole is the major site of intracellular Ca2+ storage in yeast and functions to maintain cytosolic Ca2+ levels within a narrow physiological range. In this study, we examined how cellular Ca2+ homeostasis is maintained in a vps33Delta vacuolar biogenesis mutant. We found that growth of the vps33Delta strain was sensitive to high or low extracellular Ca2+. This strain could not properly regulate cytosolic Ca2+ levels and was able to retain only a small fraction of its total cellular Ca2+ in a nonexchangeable intracellular pool. Surprisingly, the vps33Delta strain contained more total cellular Ca2+ than the wild type strain. Because most cellular Ca2+ is normally found within the vacuole, this suggested that other intracellular compartments compensated for the reduced capacity to store Ca2+ within the vacuole of this strain. To test this hypothesis, we examined the contribution of the Golgi-localized Ca2+ ATPase Pmr1p in the maintenance of cellular Ca2+ homeostasis. We found that a vps33Delta/pmr1Delta strain was hypersensitive to high extracellular Ca2+. In addition, certain combinations of mutations effecting both vacuolar and Golgi Ca2+ transport resulted in synthetic lethality. These results indicate that the Golgi apparatus plays a significant role in maintaining Ca2+ homeostasis when vacuolar biogenesis is compromised.

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Base Sequence
  • Calcium / metabolism*
  • Cytosol / metabolism
  • DNA Primers
  • Golgi Apparatus / enzymology
  • Golgi Apparatus / metabolism*
  • Homeostasis*
  • Magnesium / metabolism
  • Mutation*
  • Oxidative Stress
  • Phosphates / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Vacuoles / metabolism*

Substances

  • DNA Primers
  • Phosphates
  • Adenosine Triphosphatases
  • Magnesium
  • Calcium