Nagamatsu Yasunori, Okamura Shoutarou, Saitou Hiroyuki, Akao Tetsuyuki, Mizuki Eiichi
Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Japan.
Biosci Biotechnol Biochem. 2010;74(3):494-8. doi: 10.1271/bbb.90615. Epub 2010 Mar 7.
Bacillus thuringiensis strain M019, non-pathogenic to lepidopteran and dipteran insects, produces a parasporal inclusion that consists of three 84-kDa Cry proteins (CPs). CP78A and CP78B, which exhibit 83.5% amino acid identity, were new variants of the previously reported HeLa cell-killing protein (parasporin-1). CP84 was a novel CP showing low-level homology, of 21.9% (56.4% similarity), with the insecticidal Cry2 toxin. In vitro solubilization with dithiothreitol at pH 10.2 and limited hydrolysis with trypsin resulted in the removal of N-terminal portions of the CPs and their activation. The 70-kDa proteins (15- and 55-kDa fragments) from CP78A and CP78B and the 73-kDa protein (14- and 59-kDa fragments) from CP84 exhibited varying degrees of cytocidal activity preferentially toward human hepatocyte cancer HepG2 cells and uterus cervix cancer HeLa cells causing cell swelling or the formation of vacuoles in the cytoplasm. These toxins appeared to attack an identical target on human cells.
苏云金芽孢杆菌菌株M019对鳞翅目和双翅目昆虫无致病性，可产生一种伴孢晶体，该晶体由三种84 kDa的Cry蛋白（CPs）组成。CP78A和CP78B的氨基酸同一性为83.5%，它们是先前报道的HeLa细胞杀伤蛋白（杀孢子菌素-1）的新变体。CP84是一种新型CP，与杀虫Cry2毒素的同源性较低，为21.9%（相似性为56.4%）。在pH 10.2条件下用二硫苏糖醇进行体外溶解，并用胰蛋白酶进行有限水解，导致CPs的N端部分被去除并被激活。CP78A和CP78B的70 kDa蛋白（15 kDa和55 kDa片段）以及CP84的73 kDa蛋白（14 kDa和59 kDa片段）对人肝癌HepG2细胞和子宫颈癌HeLa细胞表现出不同程度的杀细胞活性，导致细胞肿胀或细胞质中形成空泡。这些毒素似乎攻击人类细胞上的同一靶点。
