生长条件影响新型隐球酵母漆酶表达的比较分析

Regulation of Laccase Activity in Cryptococcus Neoformans by Different Growth Conditions

对病原真菌新型隐球酵母致病因子漆酶的表达进行了分析,实验发现不同血清型菌株漆酶表达调控有所不同,高毒性血清型A型菌株H99在稳定期初期漆酶活性高于血清型D型菌株,但漆酶活性最终值远低于D型菌株JEC21。铜离子的对二者漆酶的诱导作用也不一致,血清型A型菌株H99,漆酶的表达量随培养基中的铜离子浓度的增加而增加;而对于血清型D型菌株JEC21,则是在低浓度铜离子(10μmol/L)诱导时漆酶活性达最大值,而当培养基中铜离子的浓度继续增大,漆酶的活性逐渐降低,与葡萄糖不同,培养基中氮源对漆酶的表达有一定抑制作用,但不同氮源对漆酶的表达抑制作用不同。培养温度升高使漆酶活性降低,铜离子可以在有高糖、高温等抑制条件下诱导漆酶表达,这些观察均未见报道,对研究漆酶的生产应用和揭示其生物学功能有一定参考价值。

We presented the observations on the regulation of laccase expression by some environmental elements in Cryptococcus neoformans. We showed that regulation of laccase expression differentiated in the two most seen serotypes ： A and D. In the early stationary phase, laccase activity in serotype A strain H99 was higher than that of serotype D strain JEC21 although its maximum activity was much lower than that of JEC21. Copper induction was also distinct. Laccase activity in H99 kept increasing with a higher concentration of the copper in the medium. In contrast, the maximum laccase activity in JEC21 was obtained at low concentration of copper （10 μmol/L）, then the activity started to decrease with higher copper. Unlike glucose, nitrogen had no repression effect on laccase, rather different nitrogen sources regulated laccase expression in different fashions. Additionally, laccase activity was inhibited by ele- vated temperature in both serotypes, and copper could still activate laccase expression in 2% glucose and at high temperature, e.g. 37 ℃.