TitlePEP3 overexpression shortens lag phase but does not alter growth rate in Saccharomyces cerevisiae exposed to acetic acid stress.
Publication TypeJournal Article
Year of Publication2015
AuthorsDing, J, Holzwarth, G, C Bradford, S, Cooley, B, Yoshinaga, AS, Patton-Vogt, J, Abeliovich, H, Penner, MH, Bakalinsky, AT
JournalAppl Microbiol Biotechnol
Date Published2015 Oct
KeywordsAcetic Acid, Adaptor Proteins, Vesicular Transport, Gene Expression, Hydrogen-Ion Concentration, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Stress, Physiological, Vacuolar Proton-Translocating ATPases, Vacuoles

In fungi, two recognized mechanisms contribute to pH homeostasis: the plasma membrane proton-pumping ATPase that exports excess protons and the vacuolar proton-pumping ATPase (V-ATPase) that mediates vacuolar proton uptake. Here, we report that overexpression of PEP3 which encodes a component of the HOPS and CORVET complexes involved in vacuolar biogenesis, shortened lag phase in Saccharomyces cerevisiae exposed to acetic acid stress. By confocal microscopy, PEP3-overexpressing cells stained with the vacuolar membrane-specific dye, FM4-64 had more fragmented vacuoles than the wild-type control. The stained overexpression mutant was also found to exhibit about 3.6-fold more FM4-64 fluorescence than the wild-type control as determined by flow cytometry. While the vacuolar pH of the wild-type strain grown in the presence of 80 mM acetic acid was significantly higher than in the absence of added acid, no significant difference was observed in vacuolar pH of the overexpression strain grown either in the presence or absence of 80 mM acetic acid. Based on an indirect growth assay, the PEP3-overexpression strain exhibited higher V-ATPase activity. We hypothesize that PEP3 overexpression provides protection from acid stress by increasing vacuolar surface area and V-ATPase activity and, hence, proton-sequestering capacity.

Alternate JournalAppl. Microbiol. Biotechnol.
PubMed ID26051671
PubMed Central IDPMC5497686
Grant ListP30 ES000210 / ES / NIEHS NIH HHS / United States
R15 GM104876 / GM / NIGMS NIH HHS / United States
P30ES000210-42 / ES / NIEHS NIH HHS / United States
R15GM104876 / GM / NIGMS NIH HHS / United States