SMALL GTP-BINDING PROTEINS OF THE RHO-SUBFAMILY AND RAS-SUBFAMILY ARENOT INVOLVED IN THE ACTIN REARRANGEMENTS INDUCED BY ATTACHING AND EFFACING ESCHERICHIA-COLI

Attaching and effacing Escherichia coli (AEEC) are extracellular patho gens that induce the formation of actin-rich structures at their sites of attachment to eukaryotic host cells. We analysed whether small GTP -binding proteins of the Rho- and Ras-subfamilies, which control the c ellular actin system, are essential for these bacterial-induced microf ilament reorganizations. For this purpose we specifically inactivated them using the Clostridium difficile toxins TcdB-10463 and TcdB-1470. Such treatment led to a dramatic breakdown of the normal actin cytoske leton, but did not abrogate the bacterial-induced actin rearrangements . Our data therefore indicate that the microfilament reorganizations i nduced by AEEC are independent of those small GTP-binding proteins tha t under normal conditions control the dynamics and maintenance of the actin cytoskeleton. (C) 1998 Federation of European Microbiological So cieties. Published by Elsevier Science B.V, All rights reserved.