title: Characterization of the Bacillus cereus Nhe enterotoxin.
abstract: 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 : His6-NheC was 10 : 10 : 1, and it was shown that NheB was the binding component of the enterotoxin complex.
authors.affiliation: Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, PO Box 8146 Dep., N-0033 Oslo, Norway.
authors.forename: Toril
authors.initials: T
authors.lastname: Lindbäck
authors.forename: Annette
authors.initials: A
authors.lastname: Fagerlund
authors.forename: Marianne Skeie
authors.initials: MS
authors.lastname: Rødland
authors.forename: Per Einar
authors.initials: PE
authors.lastname: Granum
mesh_terms: D000818:Animals; D001409:Bacillus cereus / Q000378:metabolism / Q000472:pathogenicity*; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D017077:Culture Media, Conditioned / Q000737:chemistry; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000633:toxicity; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D014709:Vero Cells; D014774:Virulence
chemical_list: D017077:Culture Media, Conditioned; D004768:Enterotoxins; C040792:enterotoxin, Bacillus cereus