Publications

• Cloning and characterization of a mammalian lithium-sensitive bisphosphate 3'-nucleotidase inhibited by inositol 1,4-bisphosphate.

  Spiegelberg B.D., Xiong J.-P., Smith J.J., Gu R.F., York J.D.

  Discovery of a structurally conserved metal-dependent lithium-inhibited phosphomonoesterase protein family has identified several potential cellular targets of lithium as used to treat manic depression. Here we describe identification of a novel family member using a "computer cloning" strategy. H ... >> More

  Discovery of a structurally conserved metal-dependent lithium-inhibited phosphomonoesterase protein family has identified several potential cellular targets of lithium as used to treat manic depression. Here we describe identification of a novel family member using a "computer cloning" strategy. Human and murine cDNA clones encoded proteins sharing 92% identity and were highly expressed in kidney. Native and recombinant protein harbored intrinsic magnesium-dependent bisphosphate nucleotidase activity (BPntase), which removed the 3'-phosphate from 3'-5' bisphosphate nucleosides and 3'-phosphoadenosine 5'-phosphosulfate with Km and Vmax values of 0.5 microM and 40 micromol/min/mg. Lithium uncompetitively inhibited activity with a Ki of 157 microM. Interestingly, BPntase was competitively inhibited by inositol 1,4-bisphosphate with a Ki of 15 microM. Expression of mammalian BPntase complemented defects in hal2/met22 mutant yeast. These data suggest that BPntase's physiologic role in nucleotide metabolism may be regulated by inositol signaling pathways. The presence of high levels of BPntase in the kidney are provocative in light of the roles of bisphosphorylated nucleotides in regulating salt tolerance, sulfur assimilation, detoxification, and lithium toxicity. We propose that inhibition of human BPntase may account for lithium-induced nephrotoxicity, which may be overcome by supplementation of current therapeutic regimes with inhibitors of nucleotide biosynthesis, such as methionine. << Less

  J. Biol. Chem. 274:13619-13628(1999) [PubMed] [EuropePMC]

• A salt-sensitive 3'(2'),5'-bisphosphate nucleotidase involved in sulfate activation.

  Murguia J.R., Belles J.M., Serrano R.

  Overexpression of a yeast gene, HAL2, allows the cells to tolerate higher than normal extracellular salt concentrations. HAL2 encodes a 3'(2')5'-bisphosphate nucleotidase that serves to remove the end products of sulfate transfer during cellular metabolism. The enzyme is inhibited by lithium and s ... >> More

  Overexpression of a yeast gene, HAL2, allows the cells to tolerate higher than normal extracellular salt concentrations. HAL2 encodes a 3'(2')5'-bisphosphate nucleotidase that serves to remove the end products of sulfate transfer during cellular metabolism. The enzyme is inhibited by lithium and sodium and is activated by potassium. Metabolic systems that are sensitive to salt, as well as those governing osmolyte synthesis and ion transport, offer routes by which genetic engineering can be used to improve the tolerance of various organisms to salt. << Less

  Science 267:232-234(1995) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• YtqI from Bacillus subtilis has both oligoribonuclease and pAp-phosphatase activity.

  Mechold U., Fang G., Ngo S., Ogryzko V., Danchin A.

  Oligoribonuclease is the only RNase in Escherichia coli that is able to degrade RNA oligonucleotides five residues and shorter in length. Firmicutes including Bacillus subtilis do not have an Oligoribonuclease (Orn) homologous protein and it is not yet understood which proteins accomplish the equi ... >> More

  Oligoribonuclease is the only RNase in Escherichia coli that is able to degrade RNA oligonucleotides five residues and shorter in length. Firmicutes including Bacillus subtilis do not have an Oligoribonuclease (Orn) homologous protein and it is not yet understood which proteins accomplish the equivalent function in these organisms. We had previously identified oligoribonucleases Orn from E. coli and its human homolog Sfn in a screen for proteins that are regulated by 3'-phosphoadenosine 5'-phosphate (pAp). Here, we identify YtqI as a potential functional analog of Orn through its interaction with pAp. YtqI degrades RNA oligonucleotides in vitro with preference for 3-mers. In addition, YtqI has pAp-phosphatase activity in vitro. In agreement with these data, YtqI is able to complement both orn and cysQ mutants in E. coli. An ytqI mutant in B. subtilis shows impairment of growth in the absence of cysteine, a phenotype resembling that of a cysQ mutant in E. coli. Phylogenetic distribution of YtqI, Orn and CysQ supports bifunctionality of YtqI. << Less

  Nucleic Acids Res. 35:4552-4561(2007) [PubMed] [EuropePMC]

• Rv2131c from Mycobacterium tuberculosis is a CysQ 3'-phosphoadenosine-5'-phosphatase.

  Hatzios S.K., Iavarone A.T., Bertozzi C.R.

  Mycobacterium tuberculosis ( Mtb) produces a number of sulfur-containing metabolites that contribute to its pathogenesis and ability to survive in the host. These metabolites are products of the sulfate assimilation pathway. CysQ, a 3'-phosphoadenosine-5'-phosphatase, is considered an important re ... >> More

  Mycobacterium tuberculosis ( Mtb) produces a number of sulfur-containing metabolites that contribute to its pathogenesis and ability to survive in the host. These metabolites are products of the sulfate assimilation pathway. CysQ, a 3'-phosphoadenosine-5'-phosphatase, is considered an important regulator of this pathway in plants, yeast, and other bacteria. By controlling the pools of 3'-phosphoadenosine 5'-phosphate (PAP) and 3'-phosphoadenosine 5'-phosphosulfate (PAPS), CysQ has the potential to modulate flux in the biosynthesis of essential sulfur-containing metabolites. Bioinformatic analysis of the Mtb genome suggests the presence of a CysQ homologue encoded by the gene Rv2131c. However, a recent biochemical study assigned the protein's function as a class IV fructose-1,6-bisphosphatase. In the present study, we expressed Rv2131c heterologously and found that the protein dephosphorylates PAP in a magnesium-dependent manner, with optimal activity observed between pH 8.5 and pH 9.5 using 0.5 mM MgCl 2. A sensitive electrospray ionization mass spectrometry-based assay was used to extract the kinetic parameters for PAP, revealing a K m (8.1 +/-3.1 microM) and k cat (5.4 +/-1.1 s (-1)) comparable to those reported for other CysQ enzymes. The second-order rate constant for PAP was determined to be over 3 orders of magnitude greater than those determined for myo-inositol 1-phosphate (IMP) and fructose 1,6-bisphosphate (FBP), previously considered to be the primary substrates of this enzyme. Moreover, the ability of the Rv2131c-encoded enzyme to dephosphorylate PAP and PAPS in vivo was confirmed by functional complementation of an Escherichia coli Delta cysQ mutant. Taken together, these studies indicate that Rv2131c encodes a CysQ enzyme that may play a role in mycobacterial sulfur metabolism. << Less

  Biochemistry 47:5823-5831(2008) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• A role for a lithium-inhibited Golgi nucleotidase in skeletal development and sulfation.

  Frederick J.P., Tafari A.T., Wu S.M., Megosh L.C., Chiou S.T., Irving R.P., York J.D.

  Sulfation is an important biological process that modulates the function of numerous molecules. It is directly mediated by cytosolic and Golgi sulfotransferases, which use 3'-phosphoadenosine 5'-phosphosulfate to produce sulfated acceptors and 3'-phosphoadenosine 5'-phosphate (PAP). Here, we ident ... >> More

  Sulfation is an important biological process that modulates the function of numerous molecules. It is directly mediated by cytosolic and Golgi sulfotransferases, which use 3'-phosphoadenosine 5'-phosphosulfate to produce sulfated acceptors and 3'-phosphoadenosine 5'-phosphate (PAP). Here, we identify a Golgi-resident PAP 3'-phosphatase (gPAPP) and demonstrate that its activity is potently inhibited by lithium in vitro. The inactivation of gPAPP in mice led to neonatal lethality, lung abnormalities resembling atelectasis, and dwarfism characterized by aberrant cartilage morphology. The phenotypic similarities of gPAPP mutant mice to chondrodysplastic models harboring mutations within components of the sulfation pathway lead to the discovery of undersulfated chondroitin in the absence of functional enzyme. Additionally, we observed loss of gPAPP leads to perturbations in the levels of heparan sulfate species in lung tissue and whole embryos. Our data are consistent with a model that clearance of the nucleotide product of sulfotransferases within the Golgi plays an important role in glycosaminoglycan sulfation, provide a unique genetic basis for chondrodysplasia, and define a function for gPAPP in the formation of skeletal elements derived through endochondral ossification. << Less

  Proc. Natl. Acad. Sci. U.S.A. 105:11605-11612(2008) [PubMed] [EuropePMC]

• A rice HAL2-like gene encodes a Ca(2+)-sensitive 3'(2'),5'-diphosphonucleoside 3'(2')-phosphohydrolase and complements yeast met22 and Escherichia coli cysQ mutations.

  Peng Z., Verma D.P.S.

  A plant homolog of yeast HAL2 gene (RHL) was cloned from rice (Orizya sativa L.). The RHL cDNA complemented an Escherichia coli cysteine auxotrophic mutant, cysQ, and the yeast HAL2 mutant, met22. The latter is a methionine auxotroph and cannot use sulfate, sulfite, or sulfide as sulfur sources bu ... >> More

  A plant homolog of yeast HAL2 gene (RHL) was cloned from rice (Orizya sativa L.). The RHL cDNA complemented an Escherichia coli cysteine auxotrophic mutant, cysQ, and the yeast HAL2 mutant, met22. The latter is a methionine auxotroph and cannot use sulfate, sulfite, or sulfide as sulfur sources but exhibits wild-type activities of the enzymes necessary to assimilate sulfate and has normal sulfur uptake system. These results demonstrated that HAL2, cysQ, and RHL genes encode proteins with similar function in sulfur assimilatory pathway. The RHL cDNA expressed a 40-kDa protein that was shown to catalyze the conversion of adenosine 3'-phosphate 5'-phosphosulfate (PAPS) to adenosine 5'-phosphosulfate (APS) and 3'(2')-phosphoadenosine 5'-phosphate (PAP) to AMP. The enzyme activity is Mg(2+)-dependent, sensitive to Ca2+, Li+, and Na+ and activated by K+. The inhibition by Ca2+ depends on the Mg2+/Ca2+ ratio and is reversible by high Mg2+ concentration. The substrate specificity and kinetics of RHL enzyme are very similar to the Chlorella 3'(2'),5'-diphosphonucleoside 3'(2')-phosphohydrolase (DPNPase). Our evidence suggests that this enzyme regulates the flux of sulfur in the sulfur-activation pathway by converting PAPS to APS. Several residues that are essential for the activity of this enzyme were identified by site-directed mutagenesis, and the possible role of DPNPase in salt tolerance is discussed. << Less

  J. Biol. Chem. 270:29105-29110(1995) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.