Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

From a cDNA library generated from mRNA of white leaf tissues of the ribosome-deficient mutant 'albostrians' of barley (Hordeum vulgare cv. Haisa) a cDNA was isolated carrying 54.2% identity to a recently published cDNA which codes for the diadenosine-5',5'''-P1,P4-tetraphosphate (Ap4A) hydrolase of Lupinus angustifolius (Maksel et al. (1998) Biochem. J. 329, 313-319), and 69% identity to four partial peptide sequences of Ap4A hydrolase of tomato. Overexpression in Escherichia coli revealed a protein of about 19 kDa, which exhibited Ap4A hydrolase activity and cross-reactivity with an antibody raised against a purified tomato Ap4A hydrolase (Feussner et al. (1996) Z. Naturforsch. 51c, 477-486). Expression studies showed an mRNA accumulation in all organs of a barley seedling. Possible functions of Ap4A hydrolase in plants will be discussed.
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PMID:Cloning and expression of a new cDNA from monocotyledonous plants coding for a diadenosine 5',5'''-P1,P4-tetraphosphate hydrolase from barley (Hordeum vulgare). 971 69

Human cells express at least eight members of the MutT motif protein (or nudix hydrolase) family. These enzymes are believed to eliminate toxic nucleotide derivatives from the cell and regulate the levels of important signalling nucleotides and their metabolites. Six have been fully or partially characterized: i) hMTH1 is a nucleoside triphosphatase which restricts AT-->CG transversions by specifically degrading the oxidized nucleotide 8-oxo-dGTP; ii) hAPAH1 preferentially degrades the signalling dinucleotide Ap4A; iii) DIPP is unusual in hydrolysing two seemingly unrelated signalling substrate groups - the dinucleotides Ap6A and Ap5A, and the diphosphoinositol polyphosphates; iv) DIPP2 is closely related to DIPP; v) hYSAH1 is an NDP-sugar hydrolase which prefers ADP-ribose, and vi) hGFG is a protein of unknown function encoded by the antisense transcript of the basic fibroblast growth factor gene. Although not yet associated with known hereditary or acquired disorders, the functional loss of any one of these hydrolases would be expected to be detrimental to cellular function. Furthermore, the ialA invasion gene of Bartonella bacilliformis and other invasive pathogens encodes a MutT motif Ap4A hydrolase while poxviruses express two MutT motif proteins, at least one of which is essential for infectivity. This protein family, therefore, occupies a position of some importance in controlling human health and disease.
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PMID:The MutT motif family of nucleotide phosphohydrolases in man and human pathogens (review). 1037 42

The solution structure of diadenosine 5',5'''-P1,P4-tetraphosphate hydrolase from Lupinus angustifolius L., an enzyme of the Nudix family, has been determined by heteronuclear NMR, using a torsion angle dynamics/simulated annealing protocol based on approximately 12 interresidue NOEs per residue. The structure represents the first Ap4A hydrolase to be determined, and sequence homology suggests that other members will have the same fold. The family of structures shows a well-defined fold comprised of a central four-stranded mixed beta-sheet, a two-stranded antiparallel beta-sheet and three helices (alphaI, alphaIII, alphaIV). The root-mean-squared deviation for the backbone (C',O,N,Calpha) of the rigid parts (residues 9 to 75, 97 to 115, 125 to 160) of the protein is 0.32 A. Several regions, however, show lower definition, particularly an isolated helix (alphaII) that connects two strands of the central sheet. This poor definition is mainly due to a lack of long-range NOEs between alphaII and other parts of the protein. Mapping conserved residues outside of the Nudix signature and those sensitive to an Ap4A analogue suggests that the adenosine-ribose moiety of the substrate binds into a large cleft above the four-stranded beta-sheet. Four conserved glutamate residues (Glu55, Glu58, Glu59 and Glu125) form a cluster that most likely ligates an essential magnesium ion, however, Gly41 also an expected magnesium ligand, is distant from this cluster.
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PMID:The three-dimensional structure of the Nudix enzyme diadenosine tetraphosphate hydrolase from Lupinus angustifolius L. 1118 82

Site-directed mutagenesis has been used to characterize the functions of key amino acid residues in the catalytic site of the 'nudix' hydrolase, (asymmetrical) diadenosine 5',5"'-P1,P4-tetraphosphate (Ap4A) hydrolase (EC 3.6.1.17) from Lupinus angustifolius, the three-dimensional solution structure of which has recently been solved. Residues within the nudix motif, Gly-(Xaa)5-Glu-(Xaa)7-Arg-Glu-Uaa-Xaa-(Glu)2-Xaa-Gly (where Xaa represents unspecified amino acids and Uaa represents the bulky aliphatic amino acids Ile, Leu or Val) conserved in 'nudix enzymes', and residues important for catalysis from elsewhere in the molecule, were mutated and the expressed proteins characterized. The results reveal a high degree of functional conservation between lupin asymmetric Ap4A hydrolase and the 8-oxo-dGTP hydrolase from Escherichia coli. Charged residues in positions equivalent to those that ligate an enzyme-bound metal ion in the E. coli 8-oxo-dGTP hydrolase [Harris, Wu, Massiah and Mildvan (2000) Biochemistry 39, 1655-1674] were shown to contribute to catalysis to similar extents in the lupin enzyme. Mutations E55Q, E59Q and E125Q all reduced kcat markedly, whereas mutations R54Q, E58Q and E122Q had smaller effects. None of the mutations produced a substantial change in the Km)for Ap4A, but several extensively modified the pH-dependence and fluoride-sensitivities of the hydrolase. It was concluded that the precisely positioned glutamate residues Glu-55, Glu-59 and Glu-125 are conserved as functionally significant components of the hydrolytic mechanism in both of these members of the nudix family of hydrolases.
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PMID:Characterization of active-site residues in diadenosine tetraphosphate hydrolase from Lupinus angustifolius. 1143 89

Asymmetrically cleaving diadenosine 5',5"'-P(1),P(4)-tetraphosphate (Ap4A) hydrolase activity has been detected in extracts of adult Caenorhabditis elegans and the corresponding cDNA amplified and expressed in Escherichia coli. As expected, sequence analysis shows the enzyme to be a member of the Nudix hydrolase family. The purified recombinant enzyme behaves as a typical animal Ap4A hydrolase. It hydrolyses Ap4A with a K(m) of 7 microM and k(cat) of 27 s(-1) producing AMP and ATP as products. It is also active towards other adenosine and diadenosine polyphosphates with four or more phosphate groups, but not diadenosine triphosphate, always generating ATP as one of the products. It is inhibited non-competitively by fluoride (K(i)=25 microM) and competitively by adenosine 5'-tetraphosphate with Ap4A as substrate (K(i)=10 nM). Crystals of diffraction quality with the morphology of rectangular plates were readily obtained and preliminary data collected. These crystals diffract to a minimum d-spacing of 2 A and belong to either space group C222 or C222(1). Phylogenetic analysis of known and putative Ap4A hydrolases of the Nudix family suggests that they fall into two groups comprising plant and Proteobacterial enzymes on the one hand and animal and archaeal enzymes on the other. Complete structural determination of the C. elegans Ap4A hydrolase will help determine the basis of this grouping.
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PMID:Cloning, characterisation and crystallisation of a diadenosine 5',5"'-P(1),P(4)-tetraphosphate pyrophosphohydrolase from Caenorhabditis elegans. 1173 85

Several 3'-[(32)P]adenylated dinucleoside polyphosphates (Np(n)N'p*As) were synthesized by the use of poly(A) polymerase (Sillero MAG et al., 2001, Eur J Biochem.; 268: 3605-11) and three of them, ApppA[(32)P]A or ApppAp*A, AppppAp*A and GppppGp*A, were tested as potential substrates of different dinucleoside polyphosphate degrading enzymes. Human (asymmetrical) dinucleoside tetraphosphatase (EC 3.6.1.17) acted almost randomly on both AppppAp*A, yielding approximately equal amounts of pppA + pAp*A and pA + pppAp*A, and GppppGp*, yielding pppG + pGp*A and pG + pppGp*A. Narrow-leafed lupin (Lupinus angustifolius) tetraphosphatase acted preferentially on the dinucleotide unmodified end of both AppppAp*A (yielding 90% of pppA + pAp*A and 10 % of pA + pppAp*A) and GppppGp*A (yielding 89% pppG + pGp*A and 11% of pG + pppGp*A). (Symmetrical) dinucleoside tetraphosphatase (EC 3.6.1.41) from Escherichia coli hydrolyzed AppppAp*A and GppppGp*A producing equal amounts of ppA + ppAp*A and ppG + ppGp*A, respectively, and, to a lesser extent, ApppAp*A producing pA + ppAp*A. Two dinucleoside triphosphatases (EC 3.6.1.29) (the human Fhit protein and the enzyme from yellow lupin (Lupinus luteus)) and dinucleoside tetraphosphate phosphorylase (EC 2.7.7.53) from Saccharomyces cerevisiae did not degrade the three 3'-adenylated dinucleoside polyphosphates tested.
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PMID:Selective splitting of 3'-adenylated dinucleoside polyphosphates by specific enzymes degrading dinucleoside polyphosphates. 1267 52

Dinucleoside 5',5"'- P (1), P ( n )-polyphosphates, and particularly the diadenosine compounds, have been implicated in extracellular purinergic signalling and in various intracellular processes, including DNA metabolism, tumour suppression and stress responses. If permitted to accumulate, they may also be toxic. One approach to understanding their function is through the various specific degradative enzymes that regulate their levels. Eight adenosine-5'- O -phosphorylated polyols (derivatives of glycerol, erythritol and pentaerythritol) and 11 adenosine-5'- O -phosphorothioylated polyols (derivatives of glycerol, erythritol, pentaerythritol, butanediol and pentanediol) have been tested as inhibitors of specific diadenosine tetraphosphate (Ap(4)A) hydrolases. Of these two groups of novel nucleotides, the adenosine-5'- O -phosphorothioylated polyols were generally stronger inhibitors than their adenosine-5'- O -phosphorylated counterparts. 1,4-Di(adenosine-5'- O -phosphorothio) erythritol appeared to be the strongest inhibitor of ( asymmetrical ) Ap(4)A hydrolases (EC 3.6.1.17) from both lupin and human, with K (i) values of 0.15 microM and 1.5 microM respectively. Of eight adenosine-5'- O -phosphorylated polyols, 1,4-di(adenosine-5'- O -phospho) erythritol was the only compound that inhibited the lupin enzyme. Two derivatives of pentaerythritol, di(adenosine-5'- O -phosphorothio)-di(phosphorothio) pentaerythritol and tri(adenosine-5'- O -phosphorothio)-phosphorothio-pentaerythritol, proved to be the strongest inhibitors of the prokaryotic ( symmetrical ) Ap(4)A hydrolase (EC 3.6.1.41) so far reported. The estimated K (i) values were 0.04 microM and 0.08 microM respectively. All of these inhibitors were competitive with respect to Ap(4)A. These new selectively acting Ap(4)A analogues should prove to be valuable tools for further studies of Ap(4)A function and of the enzymes involved in its metabolism.
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PMID:Adenosine-5'-O-phosphorylated and adenosine-5'-O-phosphorothioylated polyols as strong inhibitors of (symmetrical) and (asymmetrical) dinucleoside tetraphosphatases. 1269 25

Diadenosine tetraphosphate (Ap4A) hydrolase (EC 3.6.1.41) hydrolyzes Ap4A symmetrically in prokaryotes. It plays a potential role in organisms by regulating the concentration of Ap4A in vivo. To date, no three-dimensional structures of proteins with significant sequence homology to this protein have been determined. The 31.3 kDa Ap4A hydrolase from Shigella flexneri 2a has been cloned, expressed and purified using an Escherichia coli expression system. Crystals of Ap4A hydrolase have been obtained by the hanging-drop technique at 291 K using PEG 550 MME as precipitant. Ap4A hydrolase crystals diffract X-rays to 3.26 A and belong to space group P2(1), with unit-cell parameters a = 118.9, b = 54.6, c = 128.5 A, beta = 95.7 degrees.
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PMID:Preparation, crystallization and preliminary X-ray crystallographic studies of diadenosine tetraphosphate hydrolase from Shigella flexneri 2a. 1651 Dec 39

Dinucleoside polyphosphates (Np(n)N's; where N and N' are nucleosides and n = 3-6 phosphate residues) are naturally occurring compounds that may act as signaling molecules. One of the most successful approaches to understand their biological functions has been through the use of Np(n)N' analogs. Here, we present the results of studies using novel diadenosine polyphosphate analogs, with an oxymethylene group replacing one or two bridging oxygen(s) in the polyphosphate chain. These have been tested as potential substrates and/or inhibitors of the symmetrically acting Ap(4)A hydrolase [bis(5'-nucleosyl)-tetraphosphatase (symmetrical); EC 3.6.1.41] from E. coli and of two asymmetrically acting Ap(4)A hydrolases [bis(5'-nucleosyl)-tetraphosphatase (asymmetrical); EC 3.6.1.17] from humans and narrow-leaved lupin. The six chemically synthesized analogs were: ApCH(2)OpOCH(2)pA (1), ApOCH(2)pCH(2)OpA (2), ApOpCH(2)OpOpA (3), ApCH(2)OpOpOCH(2)pA (4), ApOCH(2)pOpCH(2)OpA (5) and ApOpOCH(2)pCH(2)OpOpA (6). The eukaryotic asymmetrical Ap(4)A hydrolases degrade two compounds, 3 and 5, as anticipated in their design. Analog 3 was cleaved to AMP (pA) and beta,gamma-methyleneoxy-ATP (pOCH(2)pOpA), whereas hydrolysis of analog 5 gave two molecules of alpha,beta-oxymethylene ADP (pCH(2)OpA). The relative rates of hydrolysis of these analogs were estimated. Some of the novel nucleotides were moderately good inhibitors of the asymmetrical hydrolases, having K(i) values within the range of the K(m) for Ap(4)A. By contrast, none of the six analogs were good substrates or inhibitors of the bacterial symmetrical Ap(4)A hydrolase.
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PMID:Novel diadenosine polyphosphate analogs with oxymethylene bridges replacing oxygen in the polyphosphate chain: potential substrates and/or inhibitors of Ap4A hydrolases. 1921 May 43

In this study, Rv2613c, a protein that is encoded by the open reading frame Rv2613c in Mycobacterium tuberculosis H37Rv, was expressed, purified, and characterized for the first time. The amino acid sequence of Rv2613c contained a histidine triad (HIT) motif consisting of H-phi-H-phi-H-phi-phi, where phi is a hydrophobic amino acid. This motif has been reported to be the characteristic feature of several diadenosine 5',5'''-P(1),P(4)-tetraphosphate (Ap4A) hydrolases that catalyze Ap4A to adenosine 5'-triphosphate (ATP) and adenosine monophosphate (AMP) or 2 adenosine 5'-diphosphate (ADP). However, enzymatic activity analyses for Rv2613c revealed that Ap4A was converted to ATP and ADP, but not AMP, indicating that Rv2613c has Ap4A phosphorylase activity rather than Ap4A hydrolase activity. The Ap4A phosphorylase activity has been reported for proteins containing a characteristic H-X-H-X-Q-phi-phi motif. However, no such motif was found in Rv2613c. In addition, the amino acid sequence of Rv2613c was significantly shorter compared to other proteins with Ap4A phosphorylase activity, indicating that the primary structure of Rv2613c differs from those of previously reported Ap4A phosphorylases. Kinetic analysis revealed that the K(m) values for Ap4A and phosphate were 0.10 and 0.94mM, respectively. Some enzymatic properties of Rv2613c, such as optimum pH and temperature, and bivalent metal ion requirement, were similar to those of previously reported yeast Ap4A phosphorylases. Unlike yeast Ap4A phosphorylases, Rv2613c did not catalyze the reverse phosphorolysis reaction. Taken together, it is suggested that Rv2613c is a unique protein, which has Ap4A phosphorylase activity with an HIT motif.
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PMID:Purification and molecular characterization of a novel diadenosine 5',5'''-P(1),P(4)-tetraphosphate phosphorylase from Mycobacterium tuberculosis H37Rv. 1977 16


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