A Novel Approach to Detect Toxin-Catalyzed ADP-Ribosylation in Intact Cells: Its Use to Study the Action of Pasteurella multocida Toxin
Certain microbial toxins are ADP-ribosyl-transferases, acting on specific substrate proteins. Although these toxins have been of great utility in studies of cellular regulatory processes, a simple procedure to directly study toxin-catalyzed ADP-ribosylation in intact cells has not been described. Ou...
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Published in | The Journal of cell biology Vol. 115; no. 4; pp. 949 - 958 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
New York, NY
Rockefeller University Press
01.11.1991
The Rockefeller University Press |
Subjects | |
Online Access | Get full text |
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Summary: | Certain microbial toxins are ADP-ribosyl-transferases, acting on specific substrate proteins. Although these toxins have been of great utility in studies of cellular regulatory processes, a simple procedure to directly study toxin-catalyzed ADP-ribosylation in intact cells has not been described. Our approach was to use [2-3H]adenine to metabolically label the cellular NAD+pool. Labeled proteins were then denatured with SDS, resolved by PAGE, and detected by fluorography. In this manner, we show that pertussis toxin, after a dose-dependent lag period, [3H]-labeled a 40-kD protein in intact cells. Furthermore, incubation of the gel with trichloroacetic acid at 95°C before fluorography caused the release of label from bands other than the pertussis toxin substrate, thus, allowing its selective visualization. The modification of the 40-kD protein was ascribed to ADP-ribosylation of a cysteine residue on the basis of inhibition of labeling by nicotinamide and the release of [3H]ADP-ribose from the labeled protein by mercuric acetate. Cholera toxin catalyzed the [3H]-labeling of a 46-kD protein in the [2-3H]adenine-labeled cells. Pretreatment of the cells with pertussis toxin before the labeling of NAD+with [2-3H]adenine blocked [2-3H]ADP-ribosylation catalyzed by pertussis toxin, but not that by cholera toxin. Thus, labeling with [2-3H]adenine permits the study of toxin-catalyzed ADP-ribosylation in intact cells. Pasteurella multocida toxin has recently been described as a novel and potent mitogen for Swiss 3T3 cell and acts to stimulate the phospholipase C-mediated hydrolysis of polyphosphoinositides. The basis of the action of the toxin is not known. Using the methodology described here, P. multocida toxin was not found to act by ADP-ribosylation. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0021-9525 1540-8140 |
DOI: | 10.1083/jcb.115.4.949 |