Requirement for guanosine triphosphate in the activation of adenylate cyclase by cholera toxin

Enomoto, Keiichi; Dm, Gill

doi:10.1002/jss.400100106

Cited by 67 publications

(20 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, there is growing recognition that adenylate cyclase is an extraordinarily complex enzyme and that a large number of cytoplasmic factors are involved in its activation [21]. ATP may play an important role as an allosteric factor [22] in maintaining the level of other factors such as GTP [23] or in other ways that are not yet recognized.…”

Section: Discussionmentioning

confidence: 99%

Effect of metabolic inhibitors on vasopressin‐stimulated transport systems in the toad bladder

1979

View full text Add to dashboard Cite

Vasopressin increases the permeability of receptor cells to water and, in tissues such as toad bladder, to solutes such as urea. While cyclic AMP appears to play a major role in mediating the effects of vasopressin, there is evidence that activation of the water permeability system and the urea permeability system involves separate pathways. In the present study, we have shown that inhibitors of oxidative metabolism (rotenone, dinitrophenol, and methylene blue) selectively inhibit either vasopressin-stimulated water flow or vasopressin-stimulated urea transport. There was no inhibition, however, when exogenous cyclic AMP was substituted for vasopressin, and little to no inhibition when the potent analogue 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) was employed. Rotenone had no effect on adenylate cyclase activity or cyclic AMP levels within the cell; dinitrophenol decreased adenylate cyclase activity minimally. Additional studies with vinblastine and nocodazole, inhibitors of microtubule assembly, demonstrated an inhibition of vasopressin and cyclic AMP-stimulated water flow but showed no effect on urea transport. We would conclude that water and urea transport, as examples of hormone-stimulated processes, have different links to cell metabolism, and that in addition to cyclic AMP, a non-nucleotide pathway may be involved in the action of vasopressin.

show abstract

Section: Discussionmentioning

confidence: 99%

Effect of metabolic inhibitors on vasopressin‐stimulated transport systems in the toad bladder

1979

View full text Add to dashboard Cite

show abstract

“…The 42 000 dalton protein was eluted with a nonhydrolyzable GTP analog, GTP~/S; this column eluate restored the responsiveness of the catalytic unit to guanine nucleotides. Gill and co-workers observed that ADP-ribosylation of this protein was dependent on GTP and a cytosolic protein of 15 000-20 000 daltons (107,109,110). The 42 000 dalton choleragen substrate has also been observed in other tissues, including human erythrocytes (113,144); in human erythrocytes, this protein may be located on the inner surface of the plasma membrane (115).…”

Section: Adp-ribosylation and Adenylate Cyclase Activation By Choleramentioning

confidence: 94%

“…Following binding of calcium, the p~otein under- (105,164,177,181,184). In addition to calmodulin, another cytosolic factor(s) appears in certain systems to enhance activation of pigeon erythrocyte adenylate cyclase by toxin (109,110). This factor has a molecular weight similar to that of calmodulin (15 000-20 000), but it is clearly different from it (109,110).…”

Section: Effects Of Calmodulin and Cytosolic Factors On Adenylate mentioning

confidence: 98%

Mechanism of action of choleragen andE. coli heat-labile enterotoxin: activation of adenylate cyclase by ADP-ribosylation

Moss

Vaughan

1981

Mol Cell Biochem

View full text Add to dashboard Cite

SummaryCholeragen exerts its effects on cells through the activation of adenylate cyclase. The initial event appears to be the binding of the B subunit of the toxin to ganglioside GM1 on the cell surface, following which there is a delay prior to activation of adenylate cyclase. Patching and capping of the toxin on the cell surface, perhaps involved in the internalization of the enzymatically active subunit, may be occuring during this time. The activation of adenylate cyclase, which is catalyzed by the A! peptide of choleragen, does not require the B subunit or ganglioside GMI. The A 1 peptide catalyzes the transfer of ADP-ribose from NAD to an amino acid, probably arginine, in a 42 000 dalton membrane protein. This protein appears to be the GTP-binding component (or G/F factor) of the adenylate cyclase system and is crucial to the regulation of cyclase activity by hormones such as epinephrine. ADP-ribosylation of the G/F factor is enhanced by GTP and, in some systems, by a cytosolic factor. GTP is also required for stabilization and optimal catalytic function of the choleragen-activated cyclase. Calmodulin, a calcium-binding protein, is necessary for expression of catalytic activity of the toxin-activated adenylate cyclase in brain and other tissues.The ADP-ribosyltransferase activity required for activation of the cyclase is an intrinsic property of the A 1 peptide of choleragen which is expressed only after the peptide is released from the holotoxin by reduction of a single disulfide bond. In the absence of cellular components, choleragen catalyzes the ADP-ribosylation of small guanidino compounds such as arginine as well as peptides and proteins that contain arginine. It is assumed, therefore, that the site of ADP-ribosylation in the natural acceptor protein is an arginine or similar amino acid. When guanidino compounds are not present as ADP-ribose acceptors, choleragen hydrolyzes NAD to ADP-ribose and nicotinamide at a considerably slower rate.E. coli heat-labile enterotoxin (LT) is very similar to choleragen in structure and function. It consists of two types of subunits, A and B, with sizes comparable to those of the A and B subunits of choleragen. Binding of LT to the cell surface is enhanced by prior incorporation of GM1 but not other gangliosides; the oligosaccharide of GMI specifically interacts with LT and its B subunit. The A subunit of LT exhibits ADP-ribosyltransferase activity following activation by thiol to release the A 1 peptide. The A subunit of LT can be isolated in an 'unnicked' form and thus requires, in addition to reduction by a thiol, proteolytic cleavage to generate the active A 1 peptide. Like choleragen, LT uses guanidino compounds as model ADP-ribose acceptors and catalyzes the ADP-ribosylation of a 42 000 dalton protein in cell membrane preparations.ADP-ribosyltransferases that use arginine as ADP-ribose acceptors are not restricted to bacterial systems; such an enzyme has been purified to apparent homogeneity (>500 000-fold) from turkey erythrocytes. Based on a subunit molecular...

show abstract

“…Choleragencatalyzed ADP-ribosylation of Gs a subunit (Gsa) inhibits GTP hydrolysis (5) and stabilizes an active Gsa-GTP dissociated from guanyl nucleotide-binding protein 8y subunit (Gp3) (6). ADP-ribosylation of Gsa is promoted by GTP and protein factors from both membrane and cytosolic fractions (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Kahn and Gilman purified a membrane protein, termed ADP-ribosylation factor (ARF), that enhanced choleragen-catalyzed ADP-ribosylation of purified Gsa (15).…”

Section: Gdp and Guanosine 5'-o-[bmentioning

confidence: 99%

Enhancement of choleragen ADP-ribosyltransferase activities by guanyl nucleotides and a 19-kDa membrane protein.

Tsai¹,

Noda²,

Adamik³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

102

View full text Add to dashboard Cite

Choleragen activates adenylate cyclase by catalyzing, in the presence of NAD, the ADP-ribosylation of Gs., the stimulatory guanyl nucleotide-binding protein of the cyclase system. Kahn and Gilman [Kahn, R. A. & Gilman, A. G. (1986) J. Biol. Chem. 261, 7906-7911] identified another guanyl nucleotide-binding protein termed ADP-ribosylation factor (ARF) that stimulated this reaction. It was proposed that the toxin substrate is an ARF-Gsa complex and that ARF may have a physiological role in regulation of Gsa activity. We have found that purified ARF from bovine brain enhances not only the ADP-ribosylation of Gsa but also Gs,,-independent choleragen-catalyzed reactions. These are (0) ADP-ribosylation of agmatine, a low molecular weight guanidino compound; (it) ADP-ribosylation of several proteins unrelated to Gsa; and (iii) auto-ADP-ribosylation of the toxin A1 peptide. These reactions, as well as the ADP-ribosylation of ARF itself, were stimulated by GTP or stable GTP analogues such as guanyl-5'-yl imidojly-diphosphate and guanosine 5'-O-[y-thioltriphosphate; GDP and guanosine 5'-O-[,B-thio]diphosphate were inactive. These observations are consistent with the conclusion that ARF interacts directly with the A subunit of choleragen in a GTP-dependent fashion thereby enhancing catalytic activity manifest as transfer of ADP-ribose to Gs, and other proteins, to the toxin Al peptide, or to agmatine. It is tempting to speculate that ARF may be involved in regulating one or another of the ADP-ribosyltransferases found in animal cells.Choleragen activates adenylate cyclase by catalyzing the ADP-ribosylation of a regulatory component of the cyclase complex (1). The adenylate cyclase system is composed of stimulatory and inhibitory receptors coupled through guanyl nucleotide-binding proteins, termed Gs and G1, respectively, to a catalytic unit that converts ATP to cAMP (1, 2). Gs and Gi are heterotrimers composed of a, ,B, and y subunits (1, 3). The a subunits bind and hydrolyze GTP (1). Gs and Gi are activated when GTP or a nonhydrolyzable GTP analogue-(e.g., guanylyl imidodiphosphate (p[NH]ppG), guanosine 5'-O-[y-thio]triphosphate (GTP[y-S])-is bound (1). Activation is believed to result from dissociation of the a and fry components (1, 4). Hydrolysis of GTP to GDP is associated with inactivation and subunit reassociation (1). Choleragencatalyzed ADP-ribosylation of Gs a subunit (Gsa) inhibits GTP hydrolysis (5) and stabilizes an active Gsa-GTP dissociated from guanyl nucleotide-binding protein 8y subunit (Gp3) (6). ADP-ribosylation of Gsa is promoted by GTP and protein factors from both membrane and cytosolic fractions (6-16). Kahn and Gilman purified a membrane protein, termed ADP-ribosylation factor (ARF), that enhanced choleragen-catalyzed ADP-ribosylation of purified Gsa (15). The effect of ARF was dependent on GTP and it was shown that ARF is a guanyl nucleotide-binding protein (15,16). It was proposed that ARF complexes with Gsa and thereby promotes the ability of Gsa to serve as a toxin substrate, leadi...

show abstract

Requirement for guanosine triphosphate in the activation of adenylate cyclase by cholera toxin

Cited by 67 publications

References 13 publications

Effect of metabolic inhibitors on vasopressin‐stimulated transport systems in the toad bladder

Effect of metabolic inhibitors on vasopressin‐stimulated transport systems in the toad bladder

Mechanism of action of choleragen andE. coli heat-labile enterotoxin: activation of adenylate cyclase by ADP-ribosylation

Enhancement of choleragen ADP-ribosyltransferase activities by guanyl nucleotides and a 19-kDa membrane protein.

Contact Info

Product

Resources

About