Cloning and sequencing of a Shiga-like toxin II-related gene from Escherichia coli O157:H7 strain 7279.
Escherichia coli O157:H7 strains are newly recognized pathogens associated with haemorrhagic colitis and haemolytic-uremic syndrome. In addition to Shiga-like toxin types I and II known to be produced by E. coli O157 isolates, we have identified in E. coli O157:H7 strain 7279 a third toxin, designated SLT-IIvhc, that is neutralized neither by anti-SLT-I nor by anti-SLT-II antibodies. The genes for this toxin were isolated by using a PCR-mediated cell-free cloning technique. DNA sequence analysis revealed a high degree of homologies to SLT-II and several SLT-II variants. The predicted amino acid sequence of the A subunit of SLT-IIvhc differed from that of the O91:H7 toxin VT2ha and SLT-IIc from E. coli O157:H- strain E2511 by 2 and 3 amino acids, respectively. The amino acid sequence of its B subunit was identical to VT2ha and SLT-IIc but different from SLT-II and SLT-IIv. Immunological differences of SLT-IIvhc and SLT-II as well as their different toxicity to HeLa cells presumably resulted from the small deviations within the primary structure of the B subunit.
Meyer
T
T
Institut für Hygiene und Mikrobiologie, Universität, Würzburg.
Karch
H
H
Hacker
J
J
Bocklage
H
H
Heesemann
J
J
D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry*; D004587:Electrophoresis, Agar Gel; D004768:Enterotoxins / Q000737:chemistry / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D022641:Shiga Toxin 2
D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004768:Enterotoxins; D015345:Oligonucleotide Probes; D022641:Shiga Toxin 2