Donovan W P, Dankocsik C, Gilbert M P
Ecogen Inc., Langhorne, Pennsylvania 19047.
J Bacteriol. 1988 Oct;170(10):4732-8. doi: 10.1128/jb.170.10.4732-4738.1988.
A gene encoding a 72,357-dalton (Da) crystal protein of Bacillus thuringiensis var. israelensis was isolated from a native 75-MDa plasmid by the use of a gene-specific oligonucleotide probe. Bacillus megaterium cells harboring the cloned gene (cryD) produced significant amounts of the 72-kDa protein (CryD), and the cells were highly toxic to mosquito larvae. In contrast, cryD-containing Escherichia coli cells did not produce detectable levels of the 72-kDa CryD protein. The sequence of the CryD protein, as deduced from the sequence of the cryD gene, was found to contain regions of homology with two previously described B. thuringiensis crystal proteins: a 73-kDa coleopteran-toxic protein and a 66-kDa lepidopteran- and dipteran-toxic protein of B. thuringiensis subsp. kurstaki. A second gene encoding the B. thuringiensis subsp. israelensis 28-kDa crystal protein was located approximately 1.5 kilobases upstream from and in the opposite orientation to the cryD gene.
利用基因特异性寡核苷酸探针，从天然75兆道尔顿（Da）质粒中分离出编码苏云金芽孢杆菌以色列变种72357道尔顿晶体蛋白的基因。携带克隆基因（cryD）的巨大芽孢杆菌细胞产生了大量的72千道尔顿蛋白（CryD），且这些细胞对蚊虫幼虫具有高毒性。相比之下，含有cryD的大肠杆菌细胞未产生可检测水平的72千道尔顿CryD蛋白。根据cryD基因序列推导得出的CryD蛋白序列，被发现与之前描述的两种苏云金芽孢杆菌晶体蛋白存在同源区域：一种73千道尔顿的对鞘翅目有毒的蛋白，以及苏云金芽孢杆菌库尔斯塔克亚种的一种66千道尔顿的对鳞翅目和双翅目有毒的蛋白。编码苏云金芽孢杆菌以色列变种28千道尔顿晶体蛋白的第二个基因，位于cryD基因上游约1.5千碱基处，且方向相反。
