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Molecular and Cellular Biology, August 2007, p. 5534-5543, Vol. 27, No. 15
0270-7306/07/$08.00+0 doi:10.1128/MCB.00302-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Pulmonary-Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1590,1 Laboratory Research Program, Transgenic Mouse Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-15902
Received 19 February 2007/ Returned for modification 7 May 2007/ Accepted 16 May 2007
Cholera toxin (CT) produced by Vibrio cholerae causes the devastating diarrhea of cholera by catalyzing the ADP-ribosylation of the
subunit of the intestinal Gs protein (Gs
), leading to characteristic water and electrolyte losses. Mammalian cells contain ADP-ribosyltransferases similar to CT and an ADP-ribosyl(arginine)protein hydrolase (ADPRH), which cleaves the ADP-ribose-(arginine)protein bond, regenerating native protein and completing an ADP-ribosylation cycle. We hypothesized that ADPRH might counteract intoxication by reversing the ADP-ribosylation of Gs
. Effects of intoxication on murine ADPRH/ cells were greater than those on wild-type cells and were significantly reduced by overexpression of wild-type ADPRH in ADPRH/ cells, as evidenced by both ADP-ribose-arginine content and Gs
modification. Similarly, intestinal loops in the ADPRH/ mouse were more sensitive than their wild-type counterparts to toxin effects on fluid accumulation, Gs
modification, and ADP-ribosylarginine content. Thus, CT-catalyzed ADP-ribosylation of cell proteins can be counteracted by ADPRH, which could function as a modifier gene in disease. Further, our study demonstrates that enzymatic cross talk exists between bacterial toxin ADP-ribosyltransferases and host ADP-ribosylation cycles. In disease, toxin-catalyzed ADP-ribosylation overwhelms this potential host defense system, resulting in persistence of ADP-ribosylation and intoxication of the cell.
Published ahead of print on 25 May 2007.
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