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Pseudomonas aeruginosa exoenzyme S: an adenosine diphosphate ribosyltransferase distinct from toxin A.

“…1 and Tables 2 and 3 suggest that exoenzyme S and toxin A are structurally different. The data in Table 4 show that in the presence of excess NAD+ and limiting amounts of wheat germ extract, exoenzyme S catalyzed the transfer of far more ADP-Rib than could be accounted for by the formation of an ADP-ribosylated EF-2 product such as has been described (1)(2)(3)(4) An investigation of the product formed in the presence of exoenzyme S revealed it to be stable to treatment with DNase or RNase but digestible with trypsin or Pronase. When this radiolabeled product was subjected to electrophoresis on sodium dodecyl sulfate/polyacrylamide gels, the acid-precipitable material obtained after elution of the individual gel slices indicated that the product was heterogeneous in size (Fig.…”

“…The only eukaryotic protein known to be modified by these two toxins is EF-2, and all existing information supports the conclusion that the ADP-ribosylation of EF-2 is responsible for the lethality of these two toxins (2,4). Diphtheria toxin is encoded by a phage gene (2,5), but the location of the structural gene for Pseudononas toxin A is unknown. Approximately 90% of all isolates of Pseudomonas aeruginosa tested produce toxin A (6,7).…”

“…Five prokaryotic ADP-ribosyltransferases have been described: diphtheria toxin (1,2), Pseudomonas toxin A (3, 4), T4 phage "alteration" enzyme (22), T4 phage "modification" enzyme (23), and an N4 phage enzyme (24). Existng evidence indicates that these enzymes play major roles in infection (i.e., diphtheria The reaction was carried out as described in Materials and Methods with 10 Ml of exoenzyme S and an incubation time of 15 min, with the following exceptions: both preparations of EF-1 were incubated for 60 min and the NAD+ concentration was 0.14 mM (16.5 Ci/ mol).…”

“…Existng evidence indicates that these enzymes play major roles in infection (i.e., diphtheria The reaction was carried out as described in Materials and Methods with 10 Ml of exoenzyme S and an incubation time of 15 min, with the following exceptions: both preparations of EF-1 were incubated for 60 min and the NAD+ concentration was 0.14 mM (16.5 Ci/ mol). toxin) or in the regulation of various cellular activities (i.e., T4 modification enzyme) (2,21). In addition, preliminary evidence has been presented that choleragen may be an ADP-ribosyltransferase (25).…”

“…EF-2 failed to serve as an acceptor in the reaction catalyzed by exoenzyme S, indicating a substrate specificity different from that of Pseudononas toxin A and diphtheria toxin. Furthermore, lysozyme, which serves as an acceptor in the in vitro reaction catalyzed by the T4 phage alteration enzyme (22) and the N4 virion-associated enzyme (24), was not ADP-ribosylated in the presence of exoenzyme S. The T4 modification enzyme reportedly does not ADP-ribosylate proteins present in rabbit retlculocyte extracts (2) as did exoenzyme S (Table 5). Thus, exoqnzyme S differs in its substrate specificity from previously desdribed prokaryotic ADP-ribosyltransferases.…”