title: ADP-ribosylation and de-ADP-ribosylation of the rho protein by Clostridium botulinum exoenzyme C3. Regulation by EDTA, guanine nucleotides and pH.
abstract: Pretreatment of rho protein purified from pig brain cytosol with EDTA (3 mM) for 10 min at 30 degrees C inhibited its ADP-ribosylation by Clostridium botulinum C3 ADP-ribosyltransferase by more than 90%. The EDTA effect was not caused by alteration of C3. GDP or GDP beta S present during the pretreatment period completely prevented the decrease in ADP-ribosylation with half-maximal and maximal effects at 3 and 300 microM, respectively. GTP or GTP gamma S were less efficacious in preventing the decrease in ADP-ribosylation, but were more potent (half-maximal and maximal effects at 0.1 and 3 microM, respectively). [32P]ADP-ribose incorporated in pig brain rho by C3 was de-ADP-ribosylated by the enzyme in the presence of nicotinamide and at low pH. Concomitantly, [32P]NAD was formed. The pH optima for ADP-ribosylation and de-ADP-ribosylation were pH 7.5 and 5.5, respectively. De-ADP-ribosylation was most efficient with nicotinamide, less effective with 3-acetylpyridine and not observed with 3-aminopyridine, 4-aminopyridine, 4-acetylpyridine and isonicotinic acid. As observed for the ADP-ribosylation, the de-ADP-ribosylation by C3 was maximal with the GDP-bound form of rho and blocked after EDTA treatment.
authors.affiliation: Rudolf-Buchheim-Institut für Pharmakologie, Universität Giessen, F.R.G.
authors.forename: B
authors.initials: B
authors.lastname: Habermann
authors.forename: C
authors.initials: C
authors.lastname: Mohr
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*; D000818:Animals; D001905:Botulinum Toxins; D003014:Clostridium botulinum / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000378:metabolism*; D009536:Niacinamide / Q000494:pharmacology; D013552:Swine; D020743:rhoB GTP-Binding Protein
chemical_list: D006150:Guanine Nucleotides; D008565:Membrane Proteins; D000246:Adenosine Diphosphate Ribose; D009536:Niacinamide; D004492:Edetic Acid; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020743:rhoB GTP-Binding Protein