Mapping the enzymatic active site of Pseudomonas aeruginosa exotoxin A.
Pseudomonas aeruginosa exotoxin A is a representative of a class of enzymes, the mono-ADP-ribosyl transferases, which catalyze the covalent transfer of an ADP-ribose moiety of NAD+ to a target substrate. Availability of the three-dimensional structure of exotoxin A provides the opportunity for mapping substrate binding sites and suggesting which amino acid residues may be involved in catalysis. Data from several sources have been combined to develop a proposal for the NAD+ binding site of exotoxin A: the binding of NAD+ fragments adenosine, AMP, and ADP have been delineated crystallographically to 6.0, 6.0, and 2.7 A, respectively; significant sequence homology spanning 60 residues has been found between exotoxin A and diphtheria toxin, which has the identical enzymatic activity; iodination of exotoxin A, under conditions in which only tyrosine 481 is iodinated in the enzymatic domain, abolishes ADP-ribosyl transferase activity.
Brandhuber
B J
BJ
Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309.
Allured
V S
VS
Falbel
T G
TG
McKay
D B
DB
D036002:ADP Ribose Transferases; D000595:Amino Acid Sequence; D001427:Bacterial Toxins; D001665:Binding Sites; D003461:Crystallography; D004167:Diphtheria Toxin / Q000032:analysis; D005098:Exotoxins / Q000032:analysis*; D005583:Fourier Analysis; D007455:Iodine; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D010449:Peptide Mapping; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D013774:Tetranitromethane; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D004167:Diphtheria Toxin; D005098:Exotoxins; D007455:Iodine; D008024:Ligands; D009243:NAD; D013774:Tetranitromethane; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A