The SPI1 gene, encoding a glycosylphosphatidylinositol-anchored cell wall protein, plays a prominent role in the development of yeast resistance to lipophilic weak-acid food preservatives.
The Saccharomyces cerevisiae SPI1 gene encodes a member of the glycosylphosphatidylinositol-anchored cell wall protein family. In this work we show results indicating that SPI1 expression protects the yeast cell from damage caused by weak acids used as food preservatives. This is documented by a less extended period of adaptation to growth in their presence and by a less inhibited specific growth rate for a parental strain compared with a mutant with SPI1 deleted. Maximal protection exerted by Spi1p against equivalent concentrations of the various weak acids tested was registered for the more lipophilic acids (octanoic acid, followed by benzoic acid) and was minimal for acetic acid. Weak-acid adaptation was found to involve the rapid activation of SPI1 transcription, which is dependent on the presence of the Msn2p transcription factor. Activation of SPI1 transcription upon acetic acid stress also requires Haa1p, whereas this recently described transcription factor has a negligible role in the adaptive response to benzoic acid. The expression of SPI1 was found to play a prominent role in the development of yeast resistance to 1,3-beta-glucanase in benzoic acid-stressed cells, while its involvement in acetic acid-induced resistance to the cell wall-lytic enzyme is slighter. The results are consistent with the notion that Spi1p expression upon weak-acid stress leads to cell wall remodeling, especially for the more lipophilic acids, decreasing cell wall porosity. Decreased cell wall porosity, in turn, reduces access to the plasma membrane, reducing membrane damage, intracellular acidification, and viability loss.
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Centro de Engenharia Biológica e Química, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
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D002264:Carboxylic Acids / Q000494:pharmacology*; D002473:Cell Wall / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D025141:Drug Resistance, Fungal; D005520:Food Preservatives / Q000494:pharmacology*; D015966:Gene Expression Regulation, Fungal; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D018869:Heat-Shock Response; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D002264:Carboxylic Acids; D004268:DNA-Binding Proteins; D005520:Food Preservatives; D017261:Glycosylphosphatidylinositols; C081935:MSN2 protein, S cerevisiae; D008562:Membrane Glycoproteins; C516345:SPI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors