Several GTP-binding proteins, including p21c-H-ras, are preferred substrates of Pseudomonas aeruginosa exoenzyme S.
Pseudomonas aeruginosa exoenzyme S has appeared to be relatively indiscriminate in its choice of substrates, but in fact it ADP-ribosylates only a small subset of cellular proteins and exhibits a marked preference for several different membrane-associated proteins of apparent Mr = 23,000-25,000, at least some of which appear to bind GTP. One of these is the p21 product of the proto-oncogene c-H-ras, which can be labeled to completion. ADP-ribosylation does not alter the interaction of p21c-H-ras with guanyl nucleotides, but does cause a shift in electrophoretic mobility that implies a large conformational change. Exoenzyme S modifies all of its substrates at arginine residues.
Coburn
J
J
Department of Molecular Biology and Microbiology, Tufts University Schools of Medicine, Boston, Massachusetts 02111.
Wyatt
R T
RT
Iglewski
B H
BH
Gill
D M
DM
D036002:ADP Ribose Transferases; D000818:Animals; D001427:Bacterial Toxins; D002478:Cells, Cultured; D010856:Columbidae; D015180:Electrophoresis, Gel, Two-Dimensional; D004910:Erythrocyte Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000097:blood / Q000378:metabolism*; D051379:Mice; D008970:Molecular Weight; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras); D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D013379:Substrate Specificity
D001427:Bacterial Toxins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases; C444820:exoenzyme S; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras)