Schwartz J L, Juteau M, Grochulski P, Cygler M, Préfontaine G, Brousseau R, Masson L
Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec.
FEBS Lett. 1997 Jun 30;410(2-3):397-402. doi: 10.1016/s0014-5793(97)00626-1.
Disulfide bridges were introduced into CrylAa, a Bacillus thuringiensis lepidopteran toxin, to stabilize different protein domains including domain I alpha-helical regions thought to be involved in membrane integration and permeation. Bridged mutants could not form functional ion channels in lipid bilayers in the oxidized state, but upon reduction with beta-mercaptoethanol, regained parental toxin channel activity. Our results show that unfolding of the protein around a hinge region linking domain I and II is a necessary step for pore formation. They also suggest that membrane insertion of the hydrophobic hairpin made of alpha-helices 4 and 5 in domain I plays a critical role in the formation of a functional pore.
二硫键被引入到苏云金芽孢杆菌鳞翅目毒素CrylAa中，以稳定不同的蛋白质结构域，包括被认为参与膜整合和渗透的结构域Iα-螺旋区域。在氧化状态下，桥接突变体无法在脂质双层中形成功能性离子通道，但在用β-巯基乙醇还原后，恢复了亲本毒素通道活性。我们的结果表明，围绕连接结构域I和II的铰链区域展开蛋白质是形成孔道的必要步骤。它们还表明，由结构域I中的α-螺旋4和5组成的疏水发夹在膜中的插入在功能性孔道的形成中起关键作用。
