ADP-RIBOSYLATION OF A SMALL SIZE GTP-BINDING PROTEIN IN BOVINE NEUTROPHILS BY THE C3 EXOENZYME OF CLOSTRIDIUM-BOTULINUM AND EFFECT ON THE CELL MOTILITY

A 24-kDa G protein, ADP-ribosylable by exoenzyme C3 from Clostridium botulinum and therefore related to the rho family, was found to be abundantly present in human and bovine neutrophils, and preferentially located in cytosol. In human myeloid HL60 cells, the amount of C3 substrate increased during differentiation of the HL60 cells into granulocytes. The effect of exoenzyme C3 on different functions of bovine neutrophils, namely generation of O2-, degranulation and chemotaxis, has been tested, using electropermeabilized cells. Exoenzyme C3 hardly affected the respiratory burst and the degranulation. In contrast, it efficiently inhibited the spontaneous and chemoattractantinduced motility of the cells and disorganized the actin microfilament assembly. © 1991 Academic Press, Inc.