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Determining the Effects of Intracellular pH on the Translational Response to Heat Shock
Author(s) -
Triandafillou Catherine G,
Dinner Aaron R.,
Drummond D. Allan
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.928.1
Subject(s) - intracellular , cytosol , biophysics , intracellular ph , microbiology and biotechnology , chemistry , heat shock , cytoplasm , heat shock protein , biochemistry , biology , gene , enzyme
Single‐celled organisms must be able to dynamically respond to changes in their environment to ensure survival and replication. The budding yeast S. cerevisiae grows best in acidic conditions, yet maintains cytosolic pH at or just above neutrality, expending a considerable portion of cellular ATP resources to do so. When cells experience stresses such as high temperatures or energy depletion, intracellular pH drops, equilibrating with the acidic environment. Given the strong buffering capacity of the cytosol, due mainly to an abundance of ionizable groups in biological molecules, this pH drop reflects a dramatic chemical change with wide‐ranging consequences for biological reactions in the cell. It has been shown that acidification drastically alters the material state of the cytoplasm, leading to solidification and decreased diffusion. Furthermore, acidification has been shown to be important for long‐term fitness following energy depletion. In the case of heat shock, very little is known about the interplay between changes in pH and other, more well‐studied cellular changes such as the transcription and translation of the heat shock genes, reduction in cellular energy production, and the formation of mRNA‐protein granules. In order to understand how changes in intracellular pH are interpreted by the cell, and to what degree they affect the heat shock response and cellular fitness, we use a pH‐sensitive, ratiometric GFP derivative to measure intracellular pH during acute heat shock and recovery while simultaneously measuring the induction of heat shock response proteins using quantitative, multi‐color flow cytometry. We find that the degree of cytosolic acidification alters the expression dynamics of molecular chaperones, independent of heat shock temperature and duration. We also find that cells which fail to acidify their interior suffer long‐term defects in pH regulation following stress, potentially indicating a loss of fitness. Support or Funding Information Research reported in this publication was supported by the National Institute of Biomedical Imaging And Bioengineering of the National Institutes of Health under Award Number T32EB009412 and the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE‐1144082.