Crystal structure of the cell-binding B oligomer of verotoxin-1 from E. coli
Abstract
THE Shiga toxin family, a group of cytotoxins associated with diarrhoeal diseases and the haemolytic uraemic syndrome, includes Shiga toxin from Shigella dysenteriae type 1 and verotoxins1 produced by enteropathogenic Escherichia coli. The family belongs to the A-B class of bacterial toxins, which includes the cholera toxin family, pertussis and diphtheria toxins. These toxins all have bipartite structures consisting of an enzymatic A subunit associated with a B oligomer which binds to specific cell-surface receptors, but their amino-acid sequences and pathogenic mechanisms differ. We have determined the crystal structure of the B oligomer of verotoxin-1 from E. coll. The structure unexpectedly resembles that of the B oligomer of the cholera toxin-like heat-labile enterotoxin fromE. coli2, despite the absence of detectable sequence similarity between these two proteins. This result implies a distant evolutionary relationship between the Shiga toxin and cholera toxin families. We suggest that the cell surface receptor-binding site lies in a cleft between adjacent subunits of the B pentamer, providing a potential target for drugs and vaccines to prevent toxin binding and effect.
- Publication:
-
Nature
- Pub Date:
- February 1992
- DOI:
- 10.1038/355748a0
- Bibcode:
- 1992Natur.355..748S