苏云金杆菌伴孢晶体的蛋白质和抗蛋白酶多肽及其毒力特性

PROTEINS AND PROTEINASE-RESISTANT POLYPEPTIDES OF δ-ENDOTOXINS FROM BACILLUS THURINGIENSIS AND THEIR INSECTICIDAL ACTIVITY

以SDS-聚丙烯酰胺凝胶电泳分析了19种苏云金杆菌伴孢晶体的蛋白质和抗胰蛋白酶多肽。以鳞翅目的家蚕和双翅目的致倦库蚊进行了毒力测定。根据蛋白质和抗酶多肽的特性,19种晶体可分为7个类型。晶体蛋白质的组成、溶解特性及抗酶多肽的性质与其对两种昆虫的毒力特性密切相关。含分子量为130—138 kD(千道尔顿)或130—138 kD及60—65 kD蛋白质,抗蛋白酶多肽(PRP)为68—75kD的晶体,对家蚕高毒,但绝大部分对库蚊无毒或微毒。含3种以上蛋白质(15—138kD),抗酶多肽为35—65kD的晶体,对库蚊有强烈毒性,对家蚕则无毒。缺少135kD蛋白质的两种晶体对家蚕低毒。HD-282和L-14晶体的P1蛋白质中同时含有杀鳞翅目和杀蚊毒素。讨论了伴孢晶体的蛋白质结构及结构与毒力之间的关系、晶体蛋白质及毒性肽的性质在菌株定向筛选和遗传工程研究中的意义。

Proteins, solubility in alkaline buffer and proteinase-resistant polypeptides (PRP) of parasporal crystals (δ-endotoxin) from Bacillus thuringiensis were investigated. 19 sorts of crystals were divided into 7 types. Difference of crystalline proteins were coincident with their solubility and PRP. The characters of the protein, solubility and PRP were subspecies-specific basically, but in a few of crystals they were strain-specific. There was a closed relation between the biochemistry property of crystal protein and the toxicity in 2 species of insects. Crystal. with protein of MW 130—138 kD or MW 130—138 kD and 60—65 kD, and PRP of MW 68—75 kD were high toxic in Bombyx mori (Lepidoptera), but most of them only showed weak or no toxicity in Culex fatigans (Diptera). Crystals containingmore than 3 sorts of proteins with MW 15—138 kD in major protein and MW 35—75 kD in minor protein and PRP of 35—65 kD had very strong toxicity in Culex fatigans, but no toxicity in Bombyx mori. The constructure of the crystal protein and the importance of the character in protein and PRP for the selection of expected strain and for the work of genetic engineering in Bacillus thuringiensis were discussed.