Analysis Of Programmed Cell Death Induced By Acetic Acid In Saccharomyces Cerevisiae Based On Omics Technology

In the alcoholic fermentation,acetic acid is a typical harmful inhibitor,not only reduces the quality of wine and damages traditional fermentation,but also induces cell death and hinders bioethanol production.It is beneficial to investigate the stress resistance mechanism in Saccharomyces cerevisiae under adversity by carrying out research on cell death and metabolism of yeast under acetic acid stress,and will provides theoretical guidance for developing high resistant strains and production control.In this study,we investigated the phenotype of acetic acid induced cell death in yeast,the responses of yeast to acetic acid both at transcriptional and metaboilic level,the effect on cell death induced by acetic acid of the acetylation balance,and the role of yeast Atg22p in resistance and cell death during acetic acid treatment.The main findings were as follows:1.There was no significant influence on cell death of yeast under the culture conditions ranging from pH 3.0 to 6.0,but cell death and mitochondria degradation were increased significantly with acetic acid concentration more than 30 mM.The intracellular structure and extracellular morphology of yeast cells were obviously changed during acetic acid treatment,and the cytoplasmic and mitochondrial pH were both greatly decreased upon acetic acid exposure.2.RNA-seq-based transcriptomic analysis revealed that many biological processes were greatly suppressed by acetic acid,mainly including biosynthesis of amino acids,permeases and transporters,cell wall integrity pathway,NAD(P)/NAD(P)H and intracellular pH homeostasis.In cells challenging with acetic acid,carbon metabolism and lipid metabolism were also significantly changed.In contrast,ubiquitin-dependent protein catabolic process,vesicle-mediated transport and protein folding in endoplasmic reticulum were systematically enhanced after acetic acid treatment.Moreover,the genes involved in intracellular histone acetylation and deacetylation was also changed significantly in response to acetic acid.3.GC/MS analysis showed that all analyzed intracellular amino acids were largely down-regulated in cells treated with acetic acid.The upstream metabolites of carbohydrates were accumulated,but part of downstream metabolites decreased in response to acetic acid.In addition,acetic acid treatment caused accumulation of intracellular long chain fatty acids4.10 differentially expressed genes involved in acetylation and deacetylation were selected to be overexpressed.Overexpression of 6 genes resulted in a higher mortality rate.Likewise,6 mutants of acetylation and deacetylation exhibited an increase in acetic acid-induced cell death.There was a slightly reduction in cell death with low-dose histone deacetylase inhibitor,but a massive cell death at higher dose.5.Disruption of ATG22 exhibited a reduction in acetic acid-induced cell death,which is accompanied by a decreased formation of reactive oxygen species and a higher mitochondrial membrane potential.But overexpression of Atg22p enhances cell death induced by acetic acid.atg22? mutant cells accumulate cytoplasmic amino acids during acetic acid treatment.Moreover,deletion of ATG22 promotes transcription of genes in heat shock protein family,cell wall integrity pathway and autophagy in response to acetic acid.