THE RAS-RELATED PROTEIN RAL IS MONOGLUCOSYLATED BY CLOSTRIDIUM-SORDELLII LETHAL TOXIN

Clostridium sordellii lethal toxin (LT), a cytotoxin which causes pref erential destruction of the actin cytoskeleton, has been recently iden tified as glucosyltransferase to modify the low molecular mass GTPases Rac, Ras and Rap. We report here on LT produced by C. sordellii strai n 6018 which glucosylates in addition lo Rac, Ras and Rap the Ral prot ein. LT from strain VPI9048 however does not glucosylate Ral. Besides recombinant Ral, cellular Ral is also substrate. In the GDP-bound form , Ral is a superior substrate to the GTP form. Acceptor amino acid for glucose is threonine-46 which is equivalent to threonine-35 in H-Ras located in the effector region. The Ral-glucosylating toxin is a novel isoform of Ras-modifying clostridial cytotoxins. (C) 1996 Academic Pr ess, Inc.