根虫瘟霉原始菌株及转寄主菌株在不同培养条件下胞外蛋白酶的诱导表达特性  

Characteristics of inducible extracellular proteases expressed by Zoophthora radicans original and host-adapted strains under different culture conditions

作　　者：邓米霞[1] 徐均焕[1] 

机构地区：[1]浙江大学微生物研究所,杭州310058

出　　处：《昆虫学报》2006年第6期924-929,共6页Acta Entomologica Sinica

基　　金：国家自然科学基金项目(30470063);教育部及浙江省留学归国科研启动基金

摘　　要：通过比较根虫瘟霉Zoophthora radicans3个菌株(原始菌株R0、转寄主菌株R1和R5)在不同培养条件下诱导胞外蛋白酶的差异,发现在含昆虫表皮和明胶的培养基中,均能诱导表达高水平的胞外蛋白酶,而在营养缺乏的MS培养基和营养丰富的萨氏培养基中则胞外蛋白酶的表达水平均很低。37kD的丝氨酸蛋白酶在任何条件下都能被诱导表达,是各菌株中的保守序列所编码的胞外蛋白酶。46kD的金属蛋白酶仅能在含明胶的培养基中被诱导表达,而葡萄糖可抑制其表达。在萨氏培养基中,67kD的蛋白酶条带在转寄主过程中消失了,而46kD的金属蛋白酶条带和117kD的条带随着转寄主传代数增加而明显,表明菌株在转染过程中选择表达了对新寄主具有较高基质特异性的胞外蛋白酶。A high level of protease activities were expressed both by Zoophthora radicans original strain （R0） and host-adapted strains （R1 and R5 ） when they grew in MS medium containing insect cuticle or gelatin. On the contrary, very low level of protease activities were detected in extremely poor nutrient medium （MS） or rich nutrient medium （Sabouraud＇ s dexteose broth, SDB）. A 37 kD band belonging to serine protease was found to be induced in any cultural condition, suggesting it is a conservative sequence coding protease for three strains. On the other hand, a 46 kD band belonging to metalloprotease was expressed only in MS medium containing gelatin; however, its expression could be inhibited by MS medium containing glucose. Interestingly, a protease band with molecular weight of 67 kD disappeared, whereas the bands of 46 kD and 117 kD became more obvious for isolates after several infection cycles through Plutella xylostella when isolates grew in SDB medium. The results indicated that inducible high substrate-specific extracellular protease was greatly expressed to adapt to new host during passages of subculture through P. xylosteUa.

关 键 词：根虫瘟霉 转寄主传代 胞外蛋白酶 基质特异性 诱导表达 

分 类 号：Q965.8[生物学—昆虫学]