TITLE:
Analysis of Volutin Granule Formation in Saccharomyces cerevisiae
AUTHORS:
Pamela A. Marshall, David B. De La Rosa, Lorenzo G. Sanchez, Matthew L. Starr
KEYWORDS:
Saccharomyces cerevisiae, Vacuole, Volutin, Polyphosphate
JOURNAL NAME:
Advances in Microbiology,
Vol.4 No.8,
June
23,
2014
ABSTRACT: The budding yeast Saccharomyces cerevisiae serves as an
effective model organism for many cellular pathways including phosphate
transport, accumulation, and storage. In S.
cerevisiae, phosphate is actively transported across the plasma membrane
via several phosphate carriers and is then transported into the acidic vacuole
(roughly equivalent to the mammalian lysosome with degradative functions but
with additional storage functions, such as calcium) where it is synthesized
into volutin, a storage form of polyphosphate, found in many organisms. We have
been studying volutin granule formation in wild type cells to determine the
physiological requirements for formation and in mutants to determine the
pathway by which the volutin biosynthetic proteins are transported to the
vacuole. Undertaking an analysis of volutin formation in yeast vacuoles by
blocking vacuole function with pharmacological agents, such as ionomycin and
CCCP, we see that vacuole pH as well as vacuolar calcium seems critical for
volutin formation. Different blocks in vacuolar protein sorting have
differential effects on volutin granule accumulation, with volutin granule
formation seen in all mutant strains thus far tested, except for vps33, a mutant cell strain lacking all
vacuolar structure. Our data are consistent with pleiotrophic effects of
vacuolar physiological function blocks leading to a decrease in volutin
formation.