Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.4.2.30 (PARP)
13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pertussis toxin, a protein virulence factor produced by Bordetella pertussis, is composed of an A protomer and a B oligomer. The A protomer consists of a single polypeptide, termed the S1 subunit, which disrupts transmembrane signaling by ADP-ribosylating eukaryotic G-proteins. The B oligomer, containing five polypeptides, binds to cell receptors (most likely containing carbohydrate) and delivers the S1 subunit. Current knowledge suggests that expression of ADP-ribosyltransferase activity in target eukaryotic cells arises after 1) nucleotides and membrane lipids allosterically promote the release of the S1 subunit; and 2) the single disulfide bond in the S1 subunit is reduced by reductants such as glutathione. This model suggests conditions for the proper use of the toxin as an experimental reagent.
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PMID:Pertussis toxin and target eukaryotic cells: binding, entry, and activation. 161 92

We have used site-directed insertion and point mutagenesis in an attempt to increase the cytotoxic potency and receptor-binding affinity of the diphtheria-toxin-related interleukin-2 (IL-2) fusion toxins. Previous studies have demonstrated that both the DAB486-IL-2 and DAB389-IL-2 forms of the fusion toxin consist of three functional domains: the N-terminal fragment-A-associated ADP-ribosyltransferase, the hydrophobic-membrane-associating domains, and the C-terminal receptor-binding domain of human IL-2. By insertion mutagenesis we have increased the apparent flexibility of the polypeptide chain between the membrane-associating domains and the receptor-binding domain of this fusion toxin. In comparison to DAB486-IL-2, the cytotoxic potency of the insertion mutants was increased by approximately 17-fold for high-affinity IL-2-receptor-bearing cell lines in vitro. Moreover, competitive displacement experiments using [125I]rIL-2 demonstrate that the increase in cytotoxic potency correlates with an increase in receptor-binding affinity for both the high and intermediate forms of the IL-2 receptor.
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PMID:Protein engineering of diphtheria-toxin-related interleukin-2 fusion toxins to increase cytotoxic potency for high-affinity IL-2-receptor-bearing target cells. 188 72

The post-translational poly ADP-ribosylation of proteins by the nuclear enzyme poly(ADP-ribose) polymerase (EC 2.4.2.30) involves a complex pattern of ADP-ribose polymers. We have determined how this enzyme produces the various polymer size patterns responsible for altered protein function. The results show that histone H1 and core histones are potent regulators of both the numbers and sizes of ADP-ribose polymers. Each histone induced the polymerase to synthesize a specific polymer size pattern. Various other basic and/or DNA binding proteins as well as other known stimulators of poly(ADP-ribose) polymerase (spermine, MgCl2, nicked DNA) were ineffective as polymer size modulators. Testing specific proteolytic fragments of histone H1, the polymer number and polymer size modulating activity could be mapped to specific polypeptide domains. The results suggest that histones specifically regulate the polymer termination reaction of poly(ADP-ribose) polymerase.
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PMID:Regulation of poly(ADP-ribose) polymerase. Histone-specific adaptations of reaction products. 190 93

The macromolecular self-association of ADP-ribosyltransferase protein in solution was studied by several experimental techniques: quantitative gel filtration, electrophoretic analyses in non-denaturing gels, and cross-linking the enzyme protein with glutaraldehyde, dimethyl pimelimidate, dimethyl suberimidate, dimethyl 3,3'-dithiobisproprionimidate and tetranitromethane. The self-association of the polypeptide components obtained by plasmin digestion was also determined by using the above cross-linking agents. Monomers and cross-linked dimers of the enzyme protein, possessing enzymic activity, were separated in non-denaturing gels by electrophoresis. The basic polypeptide fragments, exhibiting molecular masses of 29 kDa and 36 kDa, self-associated, whereas the polypeptides with molecular masses of 56 kDa and 42 kDa associated only to a negligible extent, indicating that the peptide regions that also bind DNA and histones are probable sites of self-association in the intact enzyme molecule. Macromolecular association of the enzyme was indicated by a protein-concentration-dependent red-shift in protein fluorescence. The specific enzymic activity of the isolated ADP-ribosyltransferase depended on the concentration of the enzyme protein, and at 2.00 microM concentration the enzyme was self-inhibitory. Dilution of the enzyme protein to 30-40 nM resulted in a large increase in its specific activity. Further dilution to 1-3 nM coincided with a marked decrease of specific activity. Direct enzymic assays of electrophoretically separated monomers and cross-linked dimers demonstrated that the dimer appears to be the active molecular species that catalyses poly(ADP-ribose) synthesis. The NAD+ glycohydrolase activity of the enzyme was also dependent on protein concentration and was highest at 1-3 nM enzyme concentration, when polymerase activity was minimal, indicating that the monomeric enzyme behaved as a glycohydrolase, whereas poly(ADP-ribosyl)ation of enzyme molecules was maximal when the enzyme tends to be self-associated to the dimeric form.
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PMID:Macromolecular association of ADP-ribosyltransferase and its correlation with enzymic activity. 214 19

The A subunit of cholera toxin contains the ADP-ribosyltransferase activity in its major constituent polypeptide A1 (Mr 23,000) which is responsible for the elevation of cAMP typically observed with most mammalian cell types after exposure to the toxin. The primary structure of the A subunit, recently established by sequence analyses, is presented and used as the basis for the secondary structure prediction according to the method of Chou and Fasman. The results indicated the presence of 27% alpha-helix, 25% beta-structure, 12% beta-turn, and 36% random coil. The majority of the beta-structure consisted of six strands located in the NH2-terminal portion of the molecule (residues 33-106) covering one-half of the region corresponding to the A1 polypeptide portion. The beta-sheet domain led immediately into the active site region characterized by the alternating structures of beta-pleated sheet and alpha-helix (residues 95-140) similar to that reported for other NAD+ binding proteins. The presence of this structural feature in the region was confirmed by the use of another predictive method (J. Garnier et al., J. Mol. Biol. 1978, 120, 97-120). In addition, two regions (residues 14-18 and 200-214), previously identified to contain binding sites for the B subunit as evidenced by chemical modification and monoclonal antibody studies, were found to be in alpha-helix configuration.
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PMID:Cholera toxin A subunit: functional sites correlated with regions of secondary structure. 240 74

Simple competitive inhibitors of the nuclear enzyme ADP-ribosyltransferase, such as 3-methoxybenzamide (3MB), are known to block mitogen-induced activation of lymphocytes by inhibiting an early event. We now report that 3MB affects neither the generation of inositol phosphates nor the increase in cytoplasmic calcium in human T lymphocytes stimulated with phytohaemagglutinin (PHA), indicating that it acts on later or parallel events. The proliferative response to the phorbol ester 12-o-tetradecanoylphorbol-13-acetate (TPA) was much less sensitive to 3MB than was the response to PHA. Similarly, the TPA-induced increases in the expression of the c-myc proto-oncogene and of the Tac polypeptide of the interleukin-2 receptor were not affected by 3MB, whereas the same responses to either PHA or the calcium ionophore A23187 were inhibited by 3MB. The data suggest that 3MB affects the calcium-mediated signal for T-lymphocyte activation, acting after the increase in cytoplasmic calcium, and possibly also affects other signal transduction pathways distinct from the hydrolysis of polyphosphoinositides. There are some similarities between the actions of 3MB and cyclosporin.
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PMID:Differential role for ADP-ribosylation in gene expression during the activation of T lymphocytes by various stimuli. 250 98

A 1.5 kilobase cDNA coding for the complete amino acid sequence of Gb, the substrate for ADP-ribosyltransferase in C1 and D botulinum toxins from bovine adrenal gland, has been isolated from a cDNA library of bovine adrenal gland. This cDNA encodes a polypeptide of 21,770 Da consisting of 193 amino acid residues, and the deduced amino acid sequence contains all the partial amino acid sequences reported previously (Narumiya, S., Sekine, A., and Fujiwara, M. (1988) J. Biol. Chem., 263, 17255-17257). Sequence comparison revealed that Gb is identical with the product of human rho clone 12 (rho A). The present results also confirmed our suggestion that the ADP-ribosylation occurs at Asn41 in the putative effector domain of the rho gene product.
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PMID:cDNA cloning of Gb, the substrate for botulinum ADP-ribosyltransferase from bovine adrenal gland and its identification as a rho gene product. 250 52

Clostridium spiroforme iotalike toxin produced time- and concentration-dependent incorporation of ADP-ribose into homo-poly-L-arginine. Polyasparagine, polyglutamic acid, polylysine, and agmatine were poor substrates. Enzyme activity was associated with the light-chain polypeptide of the toxin. The heavy chain did not possess ADP-ribosyltransferase activity, nor did it enhance or inhibit activity of the light chain. In broken-cell assays, the toxin acted mainly on G-actin, rather than F-actin. A single ADP-ribose group was transferred to each substrate molecule (G-actin). The enzyme was heat sensitive, had a pH optimum in the range of 7 to 8, was inhibited by high concentrations of nicotinamide, and was reversibly denatured by urea and guanidine. Physiological levels of nucleotides (AMP, ADP, ATP, and ADP-ribose) and cations (Na+, K+, Ca2+, and Mg2+) were not very active as enzyme inhibitors. The toxin was structurally and functionally similar to Clostridium botulinum type C2 toxin and Clostridium perfringens iota toxin. When combined with previous findings, the data suggest that a new class of mono(ADP-ribosyl)ating toxins has been found and that these agents belong to a related and possibly homologous series of binary toxins.
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PMID:Production by Clostridium spiroforme of an iotalike toxin that possesses mono(ADP-ribosyl)transferase activity: identification of a novel class of ADP-ribosyltransferases. 252 Dec 14

Recently we demonstrated the presence in calf thymocytes of a GTP-binding protein (G-protein) composed of three polypeptides, 54, 41, and 27 kDa, which was physically and functionally associated with a soluble phosphoinositides-specific phospholipase C (PI-phospholipase C). The properties of this G protein were further investigated with the following results. 1) In addition to the ability to bind [35S]guanosine-5'-[gamma-thio]triphosphate (GTP gamma S), the G-protein exhibited GTPase activity, which was enhanced by Mg2+, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol, but inhibited by sodium cholate, GTP gamma S and F-.2) The 54-kDa polypeptide was ADP-ribosylated by pertussis toxin and also by endogenous membrane-bound ADP-ribosyltransferase, but none of these three polypeptides was ADP-ribosylated by cholera toxin. 3) The G-protein did not cross-react with either anti-rat brain alpha 1 (alpha-subunit of inhibitory G-protein, G1), alpha 0 (alpha-subunit of other G1-like G-protein, G0) or beta gamma antibodies. 4) Incubation of this G Protein with GTP gamma S caused dissociation of the three polypeptides. 5) The 27 kDa polypeptide showed GTP-binding activity and enhanced the phosphatidylinositol 4,5-bisphosphate hydrolysis by purified PI-phospholipase C. These results suggest that the PI-phospholipase C-associated G-protein in calf thymocytes may be a novel one and that it is involved in the regulation of PI-phospholipase C activity.
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PMID:Properties of a novel GTP-binding protein which is associated with soluble phosphoinositides-specific phospholipase C. 283 52

Proteolysis by plasmin inactivates bovine ADP-ribosyltransferase; therefore, enzymatic activity depends exclusively on the intact enzyme molecule. The transferase was hydrolyzed by plasmin to four major polypeptides, which were characterized by affinity chromatography and N-terminal sequencing. Based on the cDNA sequence for human ADP-ribosyltransferase enzyme [Uchida, K., Morita, T., Sato, T., Ogura, T., Yamashita, R., Noguchi, S., Suzuki, H., Nyunoya, H., Miwa, M., & Sugimura, T. (1987) Biochem. Biophys. Res. Commun. 148, 617-622], a polypeptide map of the bovine enzyme was constructed by superposing the experimentally determined N-terminal sequences of the isolated polypeptides on the human sequence deduced from its cDNA. Two polypeptides, the N-terminal peptide (Mr 29,000) and the polypeptide adjacent to it (Mr 36,000), exhibited binding affinities toward DNA, whereas the C-terminal peptide (Mr 56,000), which accounts for the rest of the transferase protein, bound to the benzamide-Sepharose affinity matrix, indicating that it contains the NAD+-binding site. The fourth polypeptide (Mr 42,000) represents the C-terminal end of the larger C-terminal fragment (Mr 56,000) and was formed by a single enzymatic cut by plasmin of the polypeptide of Mr 56,000. The polypeptide of Mr 42,000 still retained the NAD+-binding site. The plasmin-catalyzed cleavage of the polypeptide of Mr 56,000-42,000 was greatly accelerated by the specific ligand NAD+. Out of a total of 96 amino acid residues sequenced here, there were only 6 conservative replacements between human and bovine ADP-ribosyltransferase.
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PMID:Polypeptide domains of ADP-ribosyltransferase obtained by digestion with plasmin. 297 49


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