Immunochemical analysis of Pseudomonas aeruginosa exotoxin A. Analysis of the His426 determinant.
This study describes a combined immunochemical and genetic approach defining a site on Pseudomonas aeruginosa exotoxin A (ETA) which is critical to the ADP-ribosyltransferase (ADPRT) activity of the toxin. The sequential epitope of a monoclonal antibody (TO-1) which binds to domain III (residues 405-613), containing the ADPRT activity of ETA, has been defined using a series of synthetic peptides. This epitope spans residues 422-432 which composes the major alpha-helical segment of domain III and includes His426 which has previously been shown to be essential for ADPRT activity (Wozniak, D.J., Hsu, L.-Y., and Galloway, D. R. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 8880-8884). The critical His426 residue which projects into a major cleft becomes exposed when the ETA protein is in an ADPRT-active configuration. Since the TC-1 mAb does not block the binding of NAD+, it is possible that the alpha-helix site containing the TC-1 epitope and the His426 residue is associated with the interaction between ETA and its elongation factor 2 substrate.
McGowan
J L
JL
Department of Microbiology, Ohio State University, Columbus 43210-1292.
Kessler
S P
SP
Anderson
D C
DC
Galloway
D R
DR
D036002:ADP Ribose Transferases; D000911:Antibodies, Monoclonal / Q000276:immunology; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D005098:Exotoxins / Q000235:genetics / Q000378:metabolism*; D006639:Histidine / Q000378:metabolism; D006868:Hydrolysis; D007150:Immunohistochemistry; D009243:NAD / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000276:immunology / Q000378:metabolism; D011233:Precipitin Tests; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D014508:Urea; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D000911:Antibodies, Monoclonal; D001427:Bacterial Toxins; D000939:Epitopes; D005098:Exotoxins; D006639:Histidine; D009243:NAD; D011065:Poly(ADP-ribose) Polymerases; D014508:Urea; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A