Characterization of the Bacillus cereus Nhe enterotoxin
Characterization of the Bacillus cereus Nhe enterotoxin
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DOI：
10.1099/mic.0.27359-0
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发表时间：
2004-12-01
期刊：
影响因子：
2.8
通讯作者：
Granum, PE
中科院分区：
文献类型：
--
作者：
Lindbäck, T;Fagerlund, A;Granum, PE
非溶血性肠毒素 (Nhe) 是导致蜡样芽孢杆菌引起的腹泻性食物中毒综合征的两种三组分肠毒素之一。 Nhe由NheA、NheB和NheC组成。编码Nhe组分的三个基因构成一个操纵子，转录起始位点位于nheA翻译起始位点上游61bp处。 nhe 基因被单独克隆，并在枯草芽孢杆菌或大肠杆菌中表达。单独表达表明所有三种成分都是生物活性所必需的。此外，NheA和NheB是从蜡样芽孢杆菌培养物上清液中纯化的。由于 NheC 似乎仅由蜡状芽胞杆菌表达少量，因此 NheC 作为组氨酸标记的融合蛋白进行表达和纯化。当NheA:NheB:His(6)-NheC的摩尔比为10:10:1时获得最大的细胞毒活性，表明NheB是肠毒素复合物的结合成分。
The non-haemolytic enterotoxin (Nhe) is one of two three-component enterotoxins responsible for the diarrhoeal food-poisoning syndrome caused by Bacillus cereus. Nhe is composed of NheA, NheB and NheC. The three genes encoding the Nhe components constitute an operon, and the transcriptional start site is located 61 bp upstream of the nheA translational start site. The nhe genes were cloned separately, and expressed in either Bacillus subtilis or Escherichia coli. Separate expression showed that all three components were required for biological activity. In addition, NheA and NheB were purified from B. cereus culture supernatants. As NheC seems to be expressed in only small amounts by B. cereus, NheC was expressed and purified as a histidine-tagged fusion protein. The maximum cytotoxic activity was obtained when the molar ratio between NheA: NheB: His(6)-NheC was 10: 10: 1, and it was shown that NheB was the binding component of the enterotoxin complex.