Importance of Cry1 δ-endotoxin domain II loops for binding specificity in Heliothis virescens (L.)
Importance of Cry1 δ-endotoxin domain II loops for binding specificity in Heliothis virescens (L.)
复制标题
DOI：
10.1128/aem.67.1.323-329.2001
复制
发表时间：
2001-01-01
影响因子：
4.4
通讯作者：
Adang, MJ
中科院分区：
文献类型：
--
作者：
Jurat-Fuentes, JL;Adang, MJ
我们构建了苏云金芽孢杆菌Cry 1毒素与烟芽夜蛾中肠膜囊泡结合的模型。刷状缘膜囊泡结合试验进行了5个Cry 1毒素，共享同源结构域II环。Cry 1Ab、Cry 1Ac、Cry 1 Ja和Cry 1Fa与I-125-Cry 1Aa竞争，证明每种毒素都与H.绿色的Cry 1Ac以高亲和力（竞争常数[K-com] = 1.1 nM）竞争I-125 Cry 1Ab结合位点。Cry 1Aa、Cry 1Fa和Cry 1 Ja也竞争I-125-Cry 1Ab结合位点，但K-com值范围为179至304 nM。Cry 1Ab竞争I-125-Cry 1AC结合位点（K-com = 73.6 nM），亲和力高于Cry 1Aa、Cry 1Fa或Cry 1 Ja。Cry 1 Ea和Cry 2Aa都不与任何I-125-Cry 1A毒素竞争。从膜囊泡制备的配体印迹，与Cry 1毒素一起探测，以扩展H.绿色的三种Cry 1A毒素，Cry 1Fa和Cry 1 Ja识别170-和110-kDa的蛋白质，可能是氨肽酶。Cry 1Ab和Cry 1Ac，以及在一定程度上Cry 1Fa，也识别130 kDa的分子。我们的囊泡结合和配体印迹结果支持结构域II环在Cry毒素对H.绿色的这些Cry 1毒素的共同结合特性与在H.绿色的
We constructed a model for Bacillus thuringiensis Cry1 toxin binding to midgut membrane vesicles from Heliothis virescens. Brush border membrane vesicle binding assays were performed with five Cry1 toxins that share homologies in domain II loops. Cry1Ab, Cry1Ac, Cry1Ja, and Cry1Fa competed with I-125-Cry1Aa, evidence that each toxin binds to the Cry1Aa binding site in H. virescens. Cry1Ac competed with high affinity (competition constant [K-com] = 1.1 nM) for I-125 Cry1Ab binding sites. Cry1Aa, Cry1Fa, and Cry1Ja also competed for I-125-Cry1Ab binding sites, though the K-com values ranged from 179 to 304 nM. Cry1Ab competed for I-125-Cry1AC binding sites (K-com = 73.6 nM) with higher affinity than Cry1Aa, Cry1Fa, or Cry1Ja. Neither Cry1Ea nor Cry2Aa competed with any of the I-125-Cry1A toxins. Ligand blots prepared from membrane vesicles were probed,vith Cry1 toxins to expand the model of Cry1 receptors in H. virescens. Three Cry1A toxins, Cry1Fa, and Cry1Ja recognized 170- and 110-kDa proteins that are probably aminopeptidases. Cry1Ab and Cry1Ac, and to some extent Cry1Fa, also recognized a 130-kDa molecule. Our vesicle binding and ligand blotting results support a determinant role for domain II loops in Cry toxin specificity for H. virescens. The shared binding properties for these Cry1 toxins correlate with observed cross-resistance in H. virescens.