Sidén I, Dalhammar G, Telander B, Boman H G, Somerville H
J Gen Microbiol. 1979 Sep;114(1):45-52. doi: 10.1099/00221287-114-1-45.
We have previously shown that Bacillus thuringiensis subsp. alesti, serotype 3, produces two extracellular inhibitors of the immune system of Saturniid pupae (designated inhibitors A and B; Edlund et al., 1976). Starting from the culture supernatant of a new mutant of B. thuringiensis with a decreased extracellular proteolytic activity, we have now purified immune inhibitor A(InA). The procedure described consists of three steps: ultrafiltration, precipitation with ammonium sulphate and chromatography on hydroxylapatite. Purified InA gave a single band on polyacrylamide gel electrophoresis using either a gel concentration of 7.5% (w/v) and reducing and denaturing conditions or a gradient gel and native conditions. In both cases the apparent molecular weight was 78 000. A certain amount of proteolytic activity was always co-purified with InA but the two activities could be dissociated by heat or EDTA treatment. Antiserum against purified InA gave only one sharp precipitation band on immunodiffusion against InA with or without EDTA. InA inhibited the in vitro killing of Escherichia coli by immune haemolymph but did not affect the killing of Bacillus subtilis. InA was toxic for Drosophila when injected into the abdomen of adult male flies.
我们先前已表明，苏云金芽孢杆菌亚种阿莱斯特亚种，血清型3，能产生两种抑制天蚕蛾蛹免疫系统的细胞外抑制剂（命名为抑制剂A和B；埃德伦德等人，1976年）。从一株细胞外蛋白水解活性降低的苏云金芽孢杆菌新突变体的培养上清液出发，我们现在已纯化出免疫抑制剂A（InA）。所述步骤包括三个阶段：超滤、硫酸铵沉淀以及羟基磷灰石层析。纯化后的InA在聚丙烯酰胺凝胶电泳上呈现单一条带，使用的凝胶浓度为7.5%（w/v），且处于还原和变性条件下，或者使用梯度凝胶并处于天然条件下。在这两种情况下，其表观分子量均为78000。总有一定量的蛋白水解活性与InA共同纯化出来，但这两种活性可通过加热或EDTA处理而解离。针对纯化后的InA制备的抗血清在与含或不含EDTA的InA进行免疫扩散时，仅产生一条清晰的沉淀带。InA抑制了免疫血淋巴对大肠杆菌的体外杀伤作用，但不影响对枯草芽孢杆菌的杀伤。将InA注射到成年雄蝇腹部时，对果蝇具有毒性。
