Cloning and sequencing of a Shiga-like toxin type II variant from Escherichia coli strain responsible for edema disease of swine.

Abstract

A Shiga-like toxin type II variant (SLT-IIv) is produced by strains of Escherichia coli responsible for edema disease of swine and is antigenically related to Shiga-like toxin type II (SLT-II) of enterohemorrhagic E. coli. However, SLT-IIv is only active against Vero cells, whereas SLT-II is active against both Vero and HeLa cells. The structural genes for SLT-IIv were cloned from E. coli S1191, and the nucleotide sequence was determined and compared with those of other members of the Shiga toxin family. The A subunit genes for SLT-IIv and SLT-II were highly homologous (94%), whereas the B subunit genes were less homologous (79%). The SLT-IIv genes were more distantly related (55 to 60% overall homology) to the genes for Shiga toxin of Shigella dysenteriae type 1 and the nearly identical Shiga-like toxin type I (SLT-I) of enterohemorrhagic E. coli. (These toxins are referred to together as Shiga toxin/SLT-I.) The A subunit of SLT-IIv, like those of other members of this toxin family, had regions of homology with the plant lectin ricin. SLT-IIv did not bind to galactose-alpha 1-4-galactose conjugated to bovine serum albumin, which is an analog of the eucaryotic cell receptor for Shiga toxin/SLT-I and SLT-II. These findings support the hypothesis that SLT-IIv binds to a different cellular receptor than do other members of the Shiga toxin family but has a similar mode of intracellular action. The organization of the SLT-IIv operon was similar to that of other members of the Shiga toxin family. Iron did not suppress SLT-IIv or SLT-II production, in contrast with its effect on Shiga toxin/SLT-I. Therefore, the regulation of synthesis of SLT-IIv and SLT-II differs from that of Shiga toxin/SLT-I.

• Authors: D L Weinstein, M P Jackson, J E Samuel, R K Holmes, A D O'Brien
• Journal: Journal of bacteriology (J Bacteriol) Vol. 170 Issue 9 Pg. 4223-30 (Sep 1988) ISSN: 0021-9193 [Print] United States
• PMID: 3045088 (Publication Type: Comparative Study, Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Bacterial Toxins
• Cytotoxins
• Shiga Toxin 1
• Ricin

Topics

• Amino Acid Sequence
• Animals
• Bacterial Toxins (genetics)
• Base Sequence
• Cloning, Molecular
• Cytotoxins (genetics)
• Edema (microbiology, veterinary)
• Escherichia coli (genetics)
• Escherichia coli Infections (microbiology, veterinary)
• Genes
• Genes, Bacterial
• Molecular Sequence Data
• Operon
• Promoter Regions, Genetic
• Ricin (genetics)
• Sequence Homology, Nucleic Acid
• Shiga Toxin 1
• Swine
• Swine Diseases (microbiology)
• Vero Cells