Glucosylation of Rho proteins by Clostridium difficile toxin B.
Toxin A and B, the major virulence factors of Clostridium difficile, are the causative agents of antibiotic-associated pseudomembranous colitis. In cultured cell lines their potent cytotoxicity results from their ability to induce disaggregation of the microfilament cytoskeleton. Toxin B acts on the low-molecular-mass GTPase RhoA, which is involved in the regulation of the actin cytoskeleton. We report here that toxin B catalyses the incorporation of up to one mole of glucose per mole of RhoA at the amino acid threonine at position 37. The modification was identified and localized by tandem electrospray mass spectrometry. UDP-glucose selectively serves as cosubstrate for the monoglucosylation reaction catalysed by toxin B. Microinjection of RhoA previously glucosylated by toxin B into monolayer cells caused disaggregation of actin filaments, indicating a dominant-negative activity of glucosylated RhoA.
Just
I
I
Institut für Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany.
Selzer
J
J
Wilm
M
M
von Eichel-Streiber
C
C
Mann
M
M
Aktories
K
K
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000378:metabolism*; D002384:Catalysis; D002478:Cells, Cultured; D016360:Clostridioides difficile; D003599:Cytoskeleton / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism*; D006031:Glycosylation; D008394:Marsupialia; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D014407:Tumor Cells, Cultured; D020742:rhoA GTP-Binding Protein
D000199:Actins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D011994:Recombinant Proteins; C031815:toxB protein, Clostridium difficile; D013912:Threonine; D005964:Glucosyltransferases; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D005947:Glucose