Studies on the active-site structure of C3-like exoenzymes: involvement of glutamic acid in catalysis of ADP-ribosylation.
Various C3-like ADP-ribosyltransferases like Clostridium botulinum exoenzyme C3, C limosum transferase, B cereus transferase and a transferase from Staphylococcus aureus (EDIN) selectively modify the low-molecular mass GTP-binding proteins RhoA,B,C. UV-irradiation of C limosum transferase in the presence of [carbonyl-14C]NAD resulted in radiolabeling of Glu-174. Concomitantly, ADP-ribosyltransferase and NAD glycohydrolase activities were inhibited. Site-directed mutagenesis of Glu-174 (E174D, E174Q) which resulted in more than 1000-fold reduction of enzyme activity, suggests that the glutamic acid residue is essentially involved in the catalytic action of C3-like transferases. These findings support the view that all bacterial ADP-ribosyltransferases share a similar active-site structure.
Institut für Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg-Saar, Germany.
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Aktories
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Jung
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Böhmer
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Fritz
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Vandekerckhove
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D036002:ADP Ribose Transferases / Q000737:chemistry* / Q000378:metabolism* / Q000528:radiation effects; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000345:Affinity Labels; D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D001905:Botulinum Toxins; D003014:Clostridium botulinum / Q000201:enzymology*; D018698:Glutamic Acid; D007700:Kinetics; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014466:Ultraviolet Rays
D000345:Affinity Labels; D001427:Bacterial Toxins; D000246:Adenosine Diphosphate Ribose; D018698:Glutamic Acid; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins