Effects Of Deletion Of Elp3 Gene On Caffeine And Hydrogen Peroxide Tolerance In S.Cerevisiae

An excess of caffeine is cytotoxic to all eukaryotic cell types.Elongator complex is six subunit histone acetyltransferase complexes,which has functional integrity.The catalytic subunit Elp3 can specifically acetylate lysine on histone H3 14th?H3K14?and histone H4 8th?H4K8?.The absence of this subunit or point mutations reduced its HAT activity can affect Elongator function,so that the yeast generate caffeine-sensitive phenotype.Elp3 not only involves in gene transcription,but also participates in cell polarity transportation and tRNA modification.To study the caffeine tolerance of Saccharomyces cerevisiae,cell growth was detected in wild-type,elp3?,H3K14R/elp3?,H3K14R/H4K8R/elp3? and full length or partial deletion Elp3 transformant by sensitivity detection and growth curve drawing under different concentrations of caffeine and/or high temperature stress conditions.The results showe that elp1? and elp3? strains are sensitive to caffeine and have similar phenotypes.Under the stress of caffeine,the growth of two conserved domain deleted elp3? transformant strains are similar to elp3? strain,While elp3? transformant strain with the full-length ELP3 gene has a phenotype that is similar to WT.In addition,the mutation on two locus?H3K14 and H4K8?will reduce the caffeine tolerance of cells.Compared with corresponding elp3? transformant strains with wild histone,transformant strains of the same gene have lower extreme concentration of caffeine.High temperature co-processing will reduce extreme concentration of the caffeine tolerance of strains.Through qRT-PCR experiments,we study the expression of three kinds of heat shock protein gene?HSP26?SSA3?HSP82?of strains under the stress of caffeine.Results show that the deletion of Elp3 or two conservative structure domain of Elp3 seriously affect the expression of heat shock proteins,and that the full-length ELP3 gene largely compensate defects in gene transcription of elp3? strain.But with the mutation on two locus?H3K14 and H4K8?,full-length ELP3 gene has almost no compensation for transcription of three heat shock proteins gene.These results indicate that the deletion of Elp3 or two conservative structure domain of Elp3 can reduce the caffeine tolerance of Saccharomyces cerevisiae,and that effects of deletion of Elp3 gene on caffeine tolerance in Saccharomyces cerevisiaehindrance may be related to hindrance in the expression of stress-related gene.We have known that Elp3 can modify tRNA,and the overexpression of tRNA^LysUUU and tRNA^GlnUUG can most compensate defective function of Elp3 deletion.To investigate whether the tRNA modify functions of Elp3 involved in the survival of saccharomyces cerevisiae under caffeine stress,we will transfer two over-expression plasmid into various strains respectively and do caffeine sensitive experiments.The results show that over-expression of two tRNAs almost no effect on caffeine tolerance of strains.Elp3 participate in stress response of Saccharomyces cerevisiae not by its influence on translation of gene.Hydrogen peroxide is an oxidizing agent commonly used in scientific research,oxidative stress response will occur in the cells under Hydrogen peroxide stress.To study the relationship between oxidative stress and Elp3,cell growth was detected in above strains by tolerance detection.The results show that Elp3 can affect the total protein content of yeast cells and the activity of superoxide dismutase?SOD?and catalase?CAT?,and its deletion decreases the hydrogen peroxide tolerance of Saccharomyces cerevisiae.With the mutation on two locus?H3K14 and H4K8?,HAT domain is more important than SAM domain in oxidative stress response in the yeast.HSP26?SSA3 and HSP82 expression in stains was detected by qRT-PCR experiments under hydrogen peroxide stress.Results show that expression of heat shock protein in the strain under hydrogen peroxide stress,and that the deletion of Elp3 or two conservative structure domain of Elp3 seriously affect the expression of heat shock proteins,and that the full-length ELP3 gene largely compensate defects in gene transcription of elp3? strain.The mutation on two locus?H3K14 and H4K8?seriously weaken the compensation of ELP3 gene for gene transcription.In addition,the overexpression of tRNA^LysUUU and tRNA^GlnUUG can partly remedy the sensitivity of strains to hydrogen peroxide.Elp3 may affect the expression of stress genes through its function on transcription and translation and by that Elp3 involve in oxidative stress response in S.cerevisiae.