title: Purification and characterization of an ADP-ribosyltransferase produced by Clostridium limosum.
abstract: We purified a novel ADP-ribosyltransferase produced by a Clostridium limosum strain isolated from a lung abscess and compared the exoenzyme with Clostridium botulinum ADP-ribosyltransferase C3. The C. limosum exoenzyme has a molecular weight of about 25,000 and a pI of 10.3. The specific activity of the ADP-ribosyltransferase is 3.1 nmol/mg/min with a Km for NAD of 0.3 microM. Partial amino acid sequence analysis of the tryptic peptides revealed about 70% homology with C3. The novel exoenzyme modifies selectively the small GTP-binding proteins of the rho family in human platelet membranes presumably at the same amino acid (asparagine 41) as known for C3. Recombinant rhoA and rhoB serve as substrates for C3 and the C. limosum exoenzyme. Whereas recombinant rac1 protein is only marginally ADP-ribosylated by C3 or by the C. limosum exoenzyme in the absence of detergent, in the presence of 0.01% sodium dodecyl sulfate rac1 is modified by C3 but not by the C. limosum exoenzyme. Recombinant CDC42Hs protein is a poor substrate for C. limosum exoenzyme and is even less modified by C3. The C. limosum exoenzyme is auto-ADP-ribosylated in the presence of 0.01% sodium dodecyl sulfate by forming an ADP-ribose protein bond highly stable toward hydroxylamine. The data indicate that ADP-ribosylation of small GTP-binding proteins of the rho family is not unique to C. botulinum C3 ADP-ribosyltransferase but is also catalyzed by a C3-related exoenzyme from C. limosum.
authors.affiliation: Institut für Pharmakologie and Toxikologie, Universität des Saarlandes, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Just
authors.forename: C
authors.initials: C
authors.lastname: Mohr
authors.forename: G
authors.initials: G
authors.lastname: Schallehn
authors.forename: L
authors.initials: L
authors.lastname: Menard
authors.forename: J R
authors.initials: JR
authors.lastname: Didsbury
authors.forename: J
authors.initials: J
authors.lastname: Vandekerckhove
authors.forename: J
authors.initials: J
authors.lastname: van Damme
authors.forename: K
authors.initials: K
authors.lastname: Aktories
mesh_terms: D036002:ADP Ribose Transferases / Q000302:isolation & purification* / Q000378:metabolism; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000595:Amino Acid Sequence; D001345:Autoradiography; D015153:Blotting, Western; D001905:Botulinum Toxins; D002851:Chromatography, High Pressure Liquid; D003013:Clostridium / Q000201:enzymology*; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D013379:Substrate Specificity
chemical_list: D007527:Isoenzymes; D000246:Adenosine Diphosphate Ribose; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins