Reconstitution of active recombinant Shiga toxin (Stx)1 from recombinant Stx1-A and Stx1-B subunits independently produced by E-coli clones

Esckerichia coli clones expressing recombinant Shiga toxin (Stx)1-A and rec ombinant Stx1-B subunits, were established. Culture supernatants of these c lones were examined for inhibitory activity on in vitro protein synthesis u sing luciferase as a reporter enzyme. Culture supernatant of the clone expr essing Stx1-A, but not Stx1-B, showed the inhibitory activity. Neither reco mbinant Stx1-A nor Stx1-B showed Vero cell cytotoxicity. For reconstitution of biologically active toxin, the culture supernatants of the Stx1-A clone and the Stx1-B clone were mixed. The reconstituted recombinant Stx1 showed both Vero cell cytotoxicity and inhibition of in vitro protein synthesis. (C) 1999 Federation of European Microbiological Societies. Published by Els evier Science B.V. All rights reserved.