Pore-forming properties of the Bacillus thuringiensis toxin Cry9Ca in Manduca sexta brush border membrane vesicles
Pore-forming properties of the Bacillus thuringiensis toxin Cry9Ca in Manduca sexta brush border membrane vesicles
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DOI：
10.1016/j.bbamem.2010.02.006
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发表时间：
2010-06-01
影响因子：
3.4
通讯作者：
Laprade, Raynald
中科院分区：
文献类型：
--
作者：
Brunet, Jean-Frederic;Vachon, Vincent;Laprade, Raynald
分别使用 Manduca sexta 新生幼虫和五龄幼虫中肠刷状缘膜囊泡，研究了苏云金芽孢杆菌 Cry9Ca 杀虫毒素、其单位点突变体 R164A 和 R164K 以及其在残基 164 处蛋白水解裂解产生的 55-kDa 片段的毒性和成孔能力。突变和蛋白水解都没有改变 Cry9Ca 的毒性。与Cry1Ac相比，Cry9Ca及其突变体在囊泡中形成了大的选择性差的孔。然而，孔的形成高度依赖于 pH，特别是对于野生型 Cry9Ca 和两种突变体。将 pH 从 6.5 增加到 10.5 会导致膜透化作用不规则地逐步降低，这与孔的离子选择性的变化无关。与 Cry1Ac 相比，Cry9Ca 及其衍生物（包括 55 kDa 片段）的孔形成速度要慢得多，并且其速率不受蛋白酶抑制剂或还原剂存在的影响。(C) 2010 Elsevier B.V. 保留所有权利。
The toxicity and pore-forming ability of the Bacillus thuringiensis Cry9Ca insecticidal toxin, its single-site mutants, R164A and R164K, and the 55-kDa fragment resulting from its proteolytic cleavage at residue 164 were investigated using Manduca sexta neonate larvae and fifth-instar larval midgut brush border membrane vesicles, respectively. Neither the mutations nor the proteolytic cleavage altered Cry9Ca toxicity. Compared with Cry1Ac, Cry9Ca and its mutants formed large poorly selective pores in the vesicles. Pore formation was highly dependent on pH, however, especially for wild-type Cry9Ca and both mutants. Increasing pH from 6.5 to 10.5 resulted in an irregular step-wise decrease in membrane permeabilization that was not related to a change in the ionic selectivity of the pores. Pore formation was much slower with Cry9Ca and its derivatives, including the 55-kDa fragment, than with Cry1Ac and its rate was not influenced by the presence of protease inhibitors or a reducing agent.(C) 2010 Elsevier B.V. All rights reserved.