聚赖氨酸偶联活性氧诱导酿酒酵母细胞凋亡

Apoptosis of Saccharomyces cerevisiae Induced byε-Poly-L-lysine Combined with Reactive Oxygen Species

以酿酒酵母为模式真菌,研究不同致死浓度ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)及其外源添加抗氧化剂N-乙酰半胱氨酸(N-acetylcysteine,NAC)共同作用下,细胞生长密度、形态和活性氧(reactive oxygen species,ROS)含量的变化及其对酿酒酵母活性的影响。结果表明,亚致死浓度处理的细胞不光滑并凹陷,ROS迸发,出现磷脂酰丝氨酸外翻、染色质固缩、线粒体膜电位耗散和DNA损伤的荧光特征,细胞进入凋亡早期阶段。致死浓度处理的细胞粗糙凹陷并凸起,ROS减少,荧光特征明显,细胞进入凋亡后期阶段甚至死亡。添加NAC后,ROS减少,荧光特征降低。因此,说明ε-PL能够诱发ROS上升,使细胞进入凋亡阶段,抑制细胞活性,此外,NAC能够降低ε-PL的抑菌活性。

In this paper,Saccharomyces cerevisiae was used as a model fungus to study the changes in cell growth,morphology and intracellular reactive oxygen species(ROS)under the combined effects of different concentrations ofε-poly-L-lysine(ε-PL)and the exogenous antioxidant N-acetylcysteine(NAC).Meanwhile,the antifungal activity ofε-PL on S.cerevisiae was explored.The results showed that the surface of cells treated withε-PL at sublethal concentration was unsmooth with pits and the cells exhibited an increased intracellular content of ROS.Fluorescence microscopy observation revealed phosphatidylserine externalization,chromatin pyknosis,mitochondrial transmembrane potential dissipation and DNA damage,which together indicate that the cells entered the early stage of apoptosis.Cells treated withε-PL at lethal concentration had a rough surface with pits and dumps and showed decreased content of intracellular ROS.Moreover,the cells displayed obvious fluorescence characteristics and entered the late stage of apoptosis and even died.After adding NAC,the content of intracellular ROS was decreased and the fluorescence characteristics were attenuated.Therefore,it is suggested thatε-PL can induce an increase in intracellular ROS,consequently leading to cell apoptosis and inhibiting cell activity.In addition,NAC could reduce the antimicrobial activity ofε-PL.