组蛋白不同乙酰化位点突变对酵母细胞生长和Ssa3、Gal1基因表达的影响

组蛋白乙酰化对基因表达和细胞生长非常重要.为揭示组蛋白H3K14和H4K8的乙酰化修饰对不同条件下细胞生长和Ssa3、Gal1基因表达的重要性及二者功能差异.构建了H3K14、H4K8分别突变为精氨酸的单突变株S14、S8及二者同时突变的双突变株D814,并对其在正常、高温、咖啡因存在等条件下生长及Ssa3、Gal1表达进行比较.结果表明,所有突变株对咖啡因敏感性增加;D814对温度敏感,且在供试条件下其生长及Ssa3和Gal1激活均明显慢于野生型和单突变株;除半乳糖和葡萄糖为单一碳源,30℃时两单突变株差别不大外,其它条件下S8生长及Ssa3和Gal1激活均慢于S14.表明H3K14、H4K8乙酰化对细胞生长和适应不利环境非常重要,而且在对不利条件的快速适应方面,H4K8的乙酰化修饰可能更为重要.组蛋白突变株的表型缺陷是因该条件下细胞生存所必需的基因激活延迟所致.

Effects of Different Mutations in Histone Acetylation Site on Ssa3 and Gal1 Transcription and Growth of Yeast Cells

Previous studies have indicated that histone acetylated modifications have great effects on gene expression and cell growth. To elucidate the different roles of H3 K14 and H4 K8 acetylated modification in yeast cell growth and SSA3，CAL1 gene expression. We constructed yeast strains carrying all three possible combinations of mutations among lysine 14 and 8 to arginine in the histone H3 and H4 tail respectively, mimicking positively charged, unacetylated lysine states, and characterized the resulting changes in SSA3 and GAL1 gene expression and cell growth by using semi-quantitative RT-PCR and sensitive assay for high temperature, caffine, high consentration of NaCl and 6-AU. In various tested conditions, three histone acetylation mutants exhibited more severe growth and SSA3， GAL1 activation defects than those of wild type; H4 K8→R / H3 K14→R double mutant strain D814 has most severe phynotype. H4 K8→R mutants S8 exhibited more severe defects than those of H3 K14→R mutants S14 except for growing on galactose and glucose plates at 30℃. H3 K14 and H4 K8 acetylation modifications are very important for the normal growth and survival at poor condition of yeast cells, different acetylation sites in histone have different effects on the gene expression in vivo. Perhaps, the acetylation of H4 K8 is more important than H3 in K14 when adaption to poor condition. The defect phynotype of histone mutant strains was result in the slow activation of induciable gene essensial for survival at new condition.