title: Salmonella enterica SpvB ADP-ribosylates actin at position arginine-177-characterization of the catalytic domain within the SpvB protein and a comparison to binary clostridial actin-ADP-ribosylating toxins.
abstract: The SpvB protein from Salmonella enterica was recently discovered as an actin-ADP-ribosylating toxin. SpvB is most likely delivered via a type-III secretion system into eukaryotic cells and does not have a binding/translocation component. This is in contrast to the family of binary actin-ADP-ribosylating toxins from various Bacillus and Clostridium species. However, there are homologies in amino acid sequences between the C-terminal domain of SpvB and the catalytic domains of the actin-ADP-ribosylating toxins such as C2 toxin from Clostridium botulinum and iota toxin from Clostridium perfringens. We compared the biochemical properties of the catalytic C-terminal domain of SpvB (C/SpvB) with the enzyme components of C2 toxin and iota toxin. The specificity of C/SpvB concerning the modification of G- or F-actin was comparable to the C2 and iota toxins, although there were distinct differences regarding the recognition of actin isoforms. C/SpvB and iota toxin modify both muscle alpha-actin and nonmuscle beta/gamma-actin, whereas C2 toxin only modifies beta/gamma-actin. In contrast to the iota and C2 toxins, C/SpvB possessed no detectable glycohydrolase activity in the absence of a protein substrate. The maximal reaction rates were comparable for all toxins, whereas variable K(m) values for NAD were evident. We identified arginine-177 as the modification site for C/SpvB with the actin homologue protein Act88F from Drosophila.
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany.
authors.forename: Henrike
authors.initials: H
authors.lastname: Hochmann
authors.forename: Sascha
authors.initials: S
authors.lastname: Pust
authors.forename: Guido
authors.initials: G
authors.lastname: von Figura
authors.forename: Klaus
authors.initials: K
authors.lastname: Aktories
authors.forename: Holger
authors.initials: H
authors.lastname: Barth
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism; D001905:Botulinum Toxins / Q000378:metabolism*; D020134:Catalytic Domain; D004330:Drosophila / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D009244:NAD+ Nucleosidase / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity; D013997:Time Factors; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D001427:Bacterial Toxins; D011994:Recombinant Proteins; D037521:Virulence Factors; C050737:iota toxin, Clostridium perfringens; C076399:flight muscle protein, Act88F; D001120:Arginine; D036002:ADP Ribose Transferases; C415223:spvB protein, Salmonella enterica virulence plasmid; D009244:NAD+ Nucleosidase; D001905:Botulinum Toxins; C096324:botulinum toxin type C