Kita E, Kamikaidou N, Nakano A, Kashiba S
Department of Bacteriology, Nara Medical University, Japan.
FEMS Microbiol Lett. 1993 May 15;109(2-3):179-84. doi: 10.1016/0378-1097(93)90016-u.
A cytotoxic protein was isolated from the sodium dodecyl sulphate (SDS)-solubilized extract of the stable L forms of Salmonella typhimurium by ion-retardation chromatography, ion-exchange chromatography, isoelectric focusing and gel filtration. The purified toxin, with a molecular mass of 32 kDa and with isoelectric point of 6.4, was thermolabile and trypsin-sensitive. Against mouse macrophages, its cytolytic effect was detectable in vitro at concentrations higher than 0.7 micrograms/ml, with a complete lysis obtained at 5 micrograms/ml. In contrast, it stimulated C3H/HeJ macrophages in the dose range of 0.1-0.5 micrograms/ml to allow the cell to respond to endotoxin, resulting in the significant production of tumor necrosis factor alpha. By Northern blot analysis, this effect was detectable at a dose as low as 0.01 micrograms/ml. These findings suggest that the transformation of bacillary S. typhimurium into L forms in vivo may induce alterations in host resistance against murine typhoid.
通过离子阻滞色谱法、离子交换色谱法、等电聚焦和凝胶过滤，从鼠伤寒沙门氏菌稳定L型的十二烷基硫酸钠（SDS）增溶提取物中分离出一种细胞毒性蛋白。纯化后的毒素分子量为32 kDa，等电点为6.4，对热不稳定且对胰蛋白酶敏感。对于小鼠巨噬细胞，其体外溶细胞作用在浓度高于0.7微克/毫升时可检测到，在5微克/毫升时可实现完全裂解。相反，在0.1 - 0.5微克/毫升的剂量范围内，它可刺激C3H/HeJ巨噬细胞，使细胞对内毒素产生反应，从而显著产生肿瘤坏死因子α。通过Northern印迹分析，在低至0.01微克/毫升的剂量下即可检测到这种作用。这些发现表明，体内鼠伤寒杆菌向L型的转变可能会引起宿主对鼠伤寒抵抗力的改变。
