Nisnevitch Marina, Cohen Shmuel, Ben-Dov Eitan, Zaritsky Arieh, Sofer Yossef, Cahan Rivka
Department of Chemical Engineering and Biotechnology, College of Judea and Samaria, Ariel 44837, Israel.
Biochem Biophys Res Commun. 2006 May 26;344(1):99-105. doi: 10.1016/j.bbrc.2006.03.134.
The gene cyt2Ba of Bacillus thuringiensis subsp. israelensis was cloned for expression, together with p20, in an acrystalliferous strain. The large hexagonal crystals formed were composed of Cyt2Ba, which facilitated its purification. Crystal solubilization in the presence of endogenous proteases (with spores and cell debris) enabled quick and simple procedure to obtain rather pure and active toxin species by cleavage between amino acid residues 34 and 35, most likely by a camelysin-like protease that was discovered in association with activated Cyt2Ba. The product of this cleavage displayed haemolytic activity comparable to that of exogenously activated Cyt2Ba. The sequence of this putative protease shares high homology with the cell envelope-bound metalloprotease (camelysin) of the closely related species Bacillus cereus.
苏云金芽孢杆菌以色列亚种的cyt2Ba基因与p20一起被克隆，以便在无晶体菌株中表达。形成的大的六边形晶体由Cyt2Ba组成，这有利于其纯化。在内源蛋白酶（存在孢子和细胞碎片）的情况下使晶体溶解，通过在氨基酸残基34和35之间切割，能够快速简单地获得相当纯且有活性的毒素种类，最有可能是由与活化的Cyt2Ba相关联而发现的一种类溶胞素蛋白酶进行切割。这种切割产物显示出与外源活化的Cyt2Ba相当的溶血活性。这种假定蛋白酶的序列与密切相关物种蜡样芽孢杆菌的细胞膜结合金属蛋白酶（溶胞素）具有高度同源性。
