title: ADP-ribosylation by Clostridium botulinum C3 exoenzyme increases steady-state GTPase activities of recombinant rhoA and rhoB proteins.
abstract: ADP-ribosylation of recombinant rhoA and rhoB proteins by Clostridium botulinum C3 exoenzyme increased steady-state GTP hydrolysis by 50 to 80%. ADP-ribosylation and increase in GTP hydrolysis occurred at similar concentrations of C3, depended on the presence of NAD and were prevented by anti-C3 antibody or heat inactivation of C3. In contrast, GTP hydrolysis by Ile-41 rhoA or Ha-ras, which are no substrates for the transferase, were not affected by C3. ADP-ribosylation facilitated the [3H]GDP release and subsequently, the binding of [3H]GTP to rhoA. The data indicate that the increase in the steady-state GTPase activity by ADP-ribosylation is caused by increasing the rate of GDP release which is suggested to be the rate limiting step of the GTPase cycle of the small GTP-binding proteins.
authors.affiliation: Rudolf-Buchheim-Institut für Pharmakologie, Universität Giessen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Mohr
authors.forename: G
authors.initials: G
authors.lastname: Koch
authors.forename: I
authors.initials: I
authors.lastname: Just
authors.forename: K
authors.initials: K
authors.lastname: Aktories
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism*; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D001905:Botulinum Toxins; D003014:Clostridium botulinum / Q000201:enzymology*; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020742:rhoA GTP-Binding Protein; D020743:rhoB GTP-Binding Protein
chemical_list: D008565:Membrane Proteins; D011994:Recombinant Proteins; D000246:Adenosine Diphosphate Ribose; D006160:Guanosine Triphosphate; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D020743:rhoB GTP-Binding Protein