酵母菌细胞自溶突变株的研究

细胞壁是酵母菌的重要细胞器 ,参与细胞内外多方面的生理生化过程 ,如细胞絮凝、信号转导、致病性等 ,在决定细胞结构完整性方面起着重要的作用。酵母细胞壁是由 β - 1 ,3-葡聚糖、β - 1 ,6-葡聚糖、甘露聚糖蛋白及几丁质等相互交链构成的复杂的双层网状结构1] 。细胞壁组成或结构的改变会使细胞产生对温度或低渗透压的敏感性 ,在相应的条件下发生自溶 ,使细胞内容物释放到胞外。产生上述效应的突变株称为温度敏感自溶突变株和低渗透敏感自溶突变株2～ 4 ] 。对此类突变株的研究一方面有利于进一步阐明酵母菌细胞壁代谢及组装的调控机制…

Studies on Yeast Mutants that Autolyse Under Hypo-osmolarity Condition

Saccharomyces cerevisiae osmotic fragile mutants were obtained from parental strain SH208 15 by N methyl N' nitro N nitrosoguanidine(NTG) treatments. Three mutants, HF2, HF7 and HF9 showed high degree of release of the intracellular components into medium under hypo osmotic condition and were studied in details. They showed some similar phenotypes to the previously reported fragile mutants, including hypo osmolarity sensitivity, temperature sensitivity and sensitivity to zymolyase indicating the existence of cell wall integrity defect. However, the three mutants differ from the reported mutants in some respects. Firstly, The temperature sensitivity of the isolated three mutants could not be complemented by osmotic stabilizer, while that of the PKC1 pathway mutants could be restored. Secondly, the degree of glycosylation of invertase in HF2, HF7 and HF9 did not decrease as that of srb1/vig9 mutants when compared with invertase in wild type strain respectively. In addition, the three mutants differ from each other. Hence, the three mutants are putative novel fragile mutants defect in cell wall. They can be used to further study the metabolism of yeast cell wall in biochemical and genetic levels and have the potential value to release intracellular heterologous proteins in high yield.