"The Defined Toxin-binding Region of the Cadherin G-protein Coupled Receptor, BT-R1, for the Active Cry1Ab Toxin of Bacillus thuringiensis".
"The Defined Toxin-binding Region of the Cadherin G-protein Coupled Receptor, BT-R1, for the Active Cry1Ab Toxin of Bacillus thuringiensis".
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DOI：
10.4172/0974-276x.1000487
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发表时间：
2018-01-01
期刊：
影响因子：
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通讯作者：
Winkler, Duane D
中科院分区：
文献类型：
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作者：
Liu, Li;Boyd, Stefanie D;Winkler, Duane D
苏云金芽孢杆菌（Bt）在副孢子晶体中产生原蛋白。原毒素的蛋白质水解产生一种活性毒素，它是一种有效的微生物杀虫剂。此外，Bt毒素基因已被引入转基因作物，以产生杀虫毒素，保护作物免受昆虫入侵。Cry毒素的杀虫活性是由毒素与其细胞受体之间的特异性相互作用介导的。其中一种毒素（Cry1Ab）首先靶向蛾钙粘蛋白受体BT-R1的第12外结构域（EC12）发挥毒性。结合促进高度调控的信号级联事件，最终导致肿瘤样细胞死亡。我们之前确定了EC12的N和c端附近的保守序列基序对昆虫细胞中的毒素结合至关重要。在这里，我们已经确定Cry1Ab特异性结合EC12作为一个可溶性异二聚体复合物具有极高的亲和力（Kd = 19.5±1.6 nM）。用Cry1Ab毒素和荧光标记的EC12结合实验表明，异二聚体复合物具有高度特异性，在EC12和其他抗甲虫和蚊子的Cry毒素之间不会形成这种复合物。破坏EC12的一个或两个末端序列基序可以消除复杂的形成。到目前为止，BT-R1受体对Cry1Ab识别和结合的全面生物物理特性尚未得到解决。本文提出的研究结果提供了对Cry毒素家族分子决定因素的见解，并应促进其作为杀虫剂的评估和发展。
The bacterium Bacillus thuringiensis (Bt) produces protoxin proteins in parasporal crystals. Proteolysis of the protoxin generates an active toxin which is a potent microbial insecticide. Additionally, Bt toxin genes have been introduced into genetically modified crops to produce insecticidal toxins which protect crops from insect invasion. The insecticidal activity of Cry toxins is mediated by specific interaction between toxins and their respective cellular receptors. One such toxin (Cry1Ab) exerts toxicity by first targeting the 12th ectodomain region (EC12) of the moth cadherin receptor BT-R1. Binding promotes a highly regulated signaling cascade event that concludes in oncotic-like cell death. We previously determined that conserved sequence motifs near the N- and C-termini of EC12 are critical for toxin binding in insect cells. Here, we have established that Cry1Ab specifically binds to EC12 as a soluble heterodimeric complex with extremely high affinity (Kd = 19.5 ± 1.6 nM). Binding assays using Cry1Ab toxin and a fluorescently labeled EC12 revealed that the heterodimeric complex is highly specific in that no such formation occurs between EC12 and other Cry toxins active against beetle and mosquito. Disruption of one or both terminal sequence motifs in EC12 eliminates complex formation. Until now, comprehensive biophysical characterization of Cry1Ab recognition and binding by the BT-R1 receptor was unresolved. The findings presented here provide insight on the molecular determinants in the Cry family of toxins and should facilitate the assessment and advancement of their use as pesticidal agents.