AI Article Synopsis
- Yeast cells have a negative surface potential due to their cell membrane's negative charges, leading to higher local concentrations of cations at the membrane.
- A new method was developed to measure local pH at the cell membrane surface, which relates to the cell's surface potential, using a specific pH reporter in yeast cells.
- The study found that the pH at the yeast cell surface was around two units lower than the surrounding medium, and this pH difference decreased when the ionic strength of the medium increased; the estimated cell surface potential was about -130 mV.
Article Abstract
Yeast cells exhibit a negative surface potential due to negative charges at the cell membrane surface. Consequently, local concentrations of cations at the periplasmic membrane surface may be significantly increased compared to their bulk environment. However, in cell suspensions only bulk concentrations of cations can be measured directly. Here we present a novel method enabling the assessment of local pH at the periplasmic membrane surface which can be directly related to the underlying cell surface potential. In this proof of concept study using Saccharomyces cerevisiae cells with episomally expressed pH reporter, pHluorin, intracellular acidification induced by the addition of the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) was measured using synchronously scanned fluorescence spectroscopy (SSF). The analysis of titration curves revealed that the pH at the periplasmic surface of S. cerevisiae cells was about two units lower than the pH of bulk medium. This pH difference was significantly decreased by increasing the ionic strength of the bulk medium. The cell surface potential was estimated to amount to -130 mV. Comparable results were obtained also with another protonophore, pentachlorophenol (PCP).
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| http://dx.doi.org/10.1007/s10863-017-9710-3 | DOI Listing |
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