title: Identification of the region of rho involved in substrate recognition by Escherichia coli cytotoxic necrotizing factor 1 (CNF1).
abstract: The Escherichia coli cytotoxic necrotizing factor 1 (CNF1) and the Bordetella dermonecrotic toxin (DNT) activate Rho GTPases by deamidation of Gln(63) of RhoA (Gln(61) of Cdc42 and Rac). In addition, both toxins possess in vitro transglutaminase activity in the presence of primary amines. Here we characterized the region of Rho essential for substrate recognition by the toxins using Rho/Ras chimeras as protein substrates. The chimeric protein Ras55Rho was deamidated or transglutaminated by CNF1. Rat pheochromocytoma PC12 cells microinjected with Ras55Rho developed formation of neurite-like structures after treatment with the CNF1 holotoxin indicating activation of the Ha-Ras chimera and Ras-like effects in intact cells. The Ras59Rho78Ras chimera protein contained the minimal Rho sequence allowing deamidation or transglutamination by CNF1. A peptide covering mainly the switch II region and consisting of amino acid residues Asp(59) through Asp(78) of RhoA was substrate for CNF1. Changes of amino acid residues Arg(68) or Leu(72) of RhoA into the corresponding residues of Ras (R68ARhoA and L72QRhoA) inhibited deamidation and transglutamination of the mutants by CNF1. In contrast to CNF1, DNT did not modify Rho/Ras chimeras or the switch II peptide (Asp(59) through Asp(78)). Glucosylation of RhoA at Thr(37) blocked deamidation by DNT but not by CNF. The data indicate that CNF1 recognizes Rho GTPases exclusively in the switch II region, whereas the substrate recognition by DNT is characterized by additional structural requirements.
authors.affiliation: Institut für Pharmakologie und Toxikologie der Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 5, D-79104 Freiburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lerm
authors.forename: G
authors.initials: G
authors.lastname: Schmidt
authors.forename: U M
authors.initials: UM
authors.lastname: Goehring
authors.forename: J
authors.initials: J
authors.lastname: Schirmer
authors.forename: K
authors.initials: K
authors.lastname: Aktories
mesh_terms: D000595:Amino Acid Sequence; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D003603:Cytotoxins / Q000378:metabolism*; D017931:DNA Primers; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006031:Glycosylation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016716:PC12 Cells; D010455:Peptides / Q000737:chemistry; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D011503:Transglutaminases / Q000378:metabolism; D010566:Virulence Factors, Bordetella; D018631:ras Proteins / Q000235:genetics
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; D010566:Virulence Factors, Bordetella; C060969:dermonecrotic toxin, Bordetella; C060296:cytotoxic necrotizing factor type 1; D000641:Ammonia; D011503:Transglutaminases; D019204:GTP-Binding Proteins; D018631:ras Proteins