RESUMO
High hydrostatic pressure (HHP) interferes with cellular membrane structure. The orientation of lipid molecules is changed, especially in the vicinity of proteins, leading to decreased membrane fluidity. Adaptation to HHP requires increased membrane fluidity, often achieved through a rise in the proportion of unsaturated fatty acids. In this work, a desaturase-deficient Saccharomyces cerevisiae mutant strain (OLE1 gene deletion) was grown in media supplemented with fatty acids differing in size and number of unsaturations and submitted to pressure up to 200 MPa for 30 min. Desaturase-deficient yeast supplemented with palmitoleic acid demonstrated increased sensitivity to pressure compared to cells supplemented with oleic acid or a proportionate mixture of both acids. In contrast, yeast cells grown with linoleic and linolenic acids were more piezoresistant than cells treated with oleic acid. Furthermore, growth with palmitoleic acid led to higher levels of lipid peroxidation. Intracellular trehalose during HHP treatment increased cell tolerance to pressure. However, when trehalose remained extracellular cells were sensitised to pressure. Therefore, fatty acid composition and trehalose content might play a role in the protection of the cell membrane from oxidative damage produced by HHP, confirming that alteration in cell membrane fluidity is correlated with pressure resistance in yeast.
Assuntos
Membrana Celular/metabolismo , Ácido Linoleico/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Estresse Fisiológico , Ácido alfa-Linolênico/metabolismo , Meios de Cultura/metabolismo , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Monoinsaturados/metabolismo , Deleção de Genes , Regulação Fúngica da Expressão Gênica , Pressão Hidrostática , Peroxidação de Lipídeos/genética , Ácido Oleico/metabolismo , Saccharomyces cerevisiae/genética , Estearoil-CoA Dessaturase , Trealose/metabolismoRESUMO
The brewing and baking yeast Saccharomyces cerevisiae is a useful eukaryotic model of stress response systems whose study could lead to the understanding of stress response mechanisms in other organisms. High hydrostatic pressure (HHP) exerts broad effects upon yeast cells, interfering with cell membranes, cellular architecture, and the processes of polymerization and denaturation of proteins. In this review, we focus on the effect of HHP on the S. cerevisiae cell membrane and describe the main signaling pathways involved in the pressure response.