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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sequence analysis of the two cDNA clones 47/11 and 50A which were isolated by differential screening of an explant cDNA library obtained from the monocot Tritordeum (hexaploid hybrid of diploid wild barley and tetraploid wheat lines) reveals that both clones include the same open reading frame (ORF). The sequence of this ORF shows a high degree of similarity with dicot S-adenosylmethionine decarboxylase (SAMDC) gene sequences and contains regions highly conserved in all known SAMDC sequences. It is further shown that the sequence represented by the cDNA clones 47/11 and 50A is derived from the wild barley (Hordeum chilense) genome, where it is present as a single-copy gene. Northern analyses indicate the corresponding transcript to accumulate in response to wounding and the transcript level changes with a circadian rhythm, having a beak in the middle of the light period. The periodicity continues in constant light, but is changed in constant darkness.
Plant Mol Biol 1996 Mar
PMID:Isolation and characterization of a Tritordeum cDNA encoding S-adenosylmethionine decarboxylase that is circadian-clock-regulated. 863 39

In the present study we have examined the regulation of the polyamine biosynthetic pathway in a cell line deficient in ornithine decarboxylase (ODC) activity. These cells were unable to grow unless polyamines were provided in their growth medium. Seeding the cells in the absence of polyamines rapidly resulted in a cellular depletion of putrescine and spermidine. Although the cells were devoid of ODC activity they were demonstrated to express an inactive ODC which was feedback regulated by polyamines in a normal manner. Cells seeded in the absence of polyamines exhibited a marked increase in ODC synthesis rate which was not correlated with an equal change in the ODC mRNA level. The synthesis of S-adenosylmethionine decarboxylase (AdoMetDC) was also increased in the cells seeded in the absence of polyamines. However, this increase was essentially explained by a change in the amount of AdoMetDC mRNA. The addition of putrescine to the growth medium appeared to stimulate the conversion of AdoMetDC proenzyme into its two subunits, indicating a physiological role of putrescine in the regulation of AdoMetDC expression.
Mol Cell Biochem 1996 Sep 20
PMID:Regulation of ornithine decarboxylase and S-adenosylmethionine decarboxylase in a polyamine auxotrophic cell line. 890 33

The polyamines are ubiquitous, multifunctional aliphatic amines with roles in cell growth, proliferation, differentiation, and malignant development. After growth stimulation, rapid and transient changes occur in polyamine regulatory enzymes. In this respect, acute effects of growth hormone (GH) injection on polyamine metabolic enzymes have earlier been shown. The present investigation comprises studies of the effects on polyamine metabolism of constitutively elevated levels of circulating GH in elderly transgenic (tg+) mice, overexpressing bovine GH. Polyamine levels were found to be constitutively altered in the liver and kidney of tg+ mice. Less changes were found in the spleen and none in the brain. The cellular uptake of polyamines in the liver from tg+ mice showed an increase and considerable changes were observed in the activity of ornithine decarboxylase (ODC) in the liver and kidney and S-adenosylmethionine decarboxylase (AdoMetDC) in the liver. A conspicuous finding was the distribution pattern of ODC protein in the liver and both tg- and tg+ animals. The results show that the effects of chronically elevated GH levels are organ-dependent and complex, and differ from acute GH effects. Despite high ODC activity and polyamine levels in liver, these mice did not display any malignant transformation even at an advanced age, indicating that high ODC activity is not sufficient to induce tumorigenesis in vivo.
Mol Cell Endocrinol 1997 Jan 03
PMID:Effects of chronically elevated growth hormone levels on polyamine metabolism in elderly transgenic mice. 902 63

S-adenosylmethionine decarboxylase (SAMDC; EC 4.1.4.50) is one of the key enzymes in polyamine biosynthesis, and the product of its catalytic reaction, decarboxylated S-adenosylmethionine (dcSAM), serves as an aminopropyl donor in the biosynthesis of spermidine and spermine. In order to provide information on the structure and regulation of SAMDC, we have isolated and sequenced two different SAMDC cDNA clones from carnation petals. The nucleotide sequences of CSDC9 and CSDC16 show 78.3% identity, and the deduced amino acid sequences show 81.7% identity and 86.5% similarity [12]. There are several regions with highly conserved sequences among SAMDC cDNAs of potato, spinach, periwinkle, man and yeast. These conserved regions include a cleavage site for the processing of SAMDC proenzyme and a putative PEST sequence that may be relevant to the rapid degradation of SAMDC protein. Carnation SAMDC cDNAs have long transcript leaders of 472 bp and 502 bp for CSDC9 and CSDC16, respectively. Both sequences contain short upstream open reading frames (uORFs) in their 5'-untranslated regions. The CSDC9 uORF is 54 amino acids from 152 to 317 while the corresponding sequence in CSDC16 is 52 amino acids located from 156 to 314 in each 5'-untranslated region. The nucleotide sequences of uORFs in CSDC9 and CSDC16 were 89.9% identical. In vitro transcription/translation experiments showed: (1) each proenzyme of both cDNAs of SAMDC was converted to two polypeptides consisting of a large subunit (calculated as 31,544 Da and 32,537 Da, respectively) and a small subunit (calculated as 9704 and 9041 Da, respectively) after 20 min of translation; (2) the processing occurs rapidly during the translation of protein. But once the translation process is stopped accumulation of the subunits slows and never reaches completion even after 300 min. The processing of carnation SAMDC enzyme is not stimulated by putrescine in in vitro transcription/translation reaction.
Plant Mol Biol 1997 Jun
PMID:Characterization and expression of two members of the S-adenosylmethionine decarboxylase gene family in carnation flower. 922 49

S-adenosylmethionine decarboxylase is a key enzyme in the synthesis of polyamines. These small cationic molecules are required for growth and development in all organisms. A wealth of biological processes, including synthesis of DNA and protein and condensation of chromatin, involve polyamines. Inhibition of polyamine synthesis has been proposed for treatment of cancer but this requires more knowledge about the in vivo function of polyamines. We report here the cloning of the S-adenosylmethionine decarboxylase gene from Drosophila melanogaster and the analysis of corresponding mutants. The mutant phenotypes are similar to those previously described for ribosomal protein genes (Minutes) and rRNA genes (bobbed). This work elucidates the in vivo consequences of impaired polyamine synthesis with respect to the development of a whole animal.
Mol Gen Genet 1997 Nov
PMID:Cloning, mapping and mutational analysis of the S-adenosylmethionine decarboxylase gene in Drosophila melanogaster. 943 90

A cDNA of tobacco BY-2 cells corresponding to an mRNA species which was rapidly induced by methyl jasmonate (MeJA) in the presence of cycloheximide (CHX) was found to encode ornithine decarboxylase (ODC). Another cDNA from a MeJA-inducible mRNA encoded S-adenosylmethionine synthase (SAMS). Although these enzymes could be involved in the biosynthesis of polyamines, the level of putrescine, a reaction product of ODC, increased slowly and while the levels of spermidine and spermine did not change following treatment of cells with MeJA. However, N-methylputrescine, which is a precursor of pyrrolidine ring of nicotine, started to increase shortly after MeJA-treatment of cells and the production of nicotine occured thereafter. The levels of mRNA for arginine decarboxylase (ADC), an alternative enzyme for putrescine synthesis, and that for S-adenosylmethionine decarboxylase (SAMDC), required for polyamine synthesis, were not affected by MeJA. In addition to mRNAs for ODC and SAMS, mRNA for putrescine N-methyltransferase (PMT) was also induced by MeJA. Unlike the MeJA-induction of ODC mRNA, MeJA-induction of SAMS and PMT mRNAs were blocked by CHX. The level of ODC mRNA declined after 1 to 4 h following MeJA treatment, while the levels of mRNAs for SAMS and PMT continued to increase. Auxin significantly reduced the MeJA-inducible accumulation of mRNAs for ODC, SAMS and PMT. These results indicate that MeJA sequentially induces expression of a series of genes involved in nicotine biosynthesis by multiple regulatory mechanisms.
Plant Mol Biol 1998 Dec
PMID:Differential induction by methyl jasmonate of genes encoding ornithine decarboxylase and other enzymes involved in nicotine biosynthesis in tobacco cell cultures. 986 16

Polyamines are essential for cell growth and differentiation and therefore, S-adenosylmethionine decarboxylase (SAMDC), a key regulatory enzyme of the polyamine biosynthesis, is considered as a potentially important target for chemotherapy of filarial infections. Recombinant Onchocerca volvulus SAMDC was expressed in Escherichia coli and characterised. The enzyme activity was found to be stimulated 15-fold by addition of 1 mM putrescine. The Km-value for S-adenosylmethionine was determined to be 36 microM. Furthermore, the efficiencies of SAMDC inhibitors were analysed: Berenil inhibits the enzyme activity competitively with a Ki-value of 0.1 microM. MDL 73811 acts as an irreversible inhibitor with a Ki-value of 1.4 microM. Recently synthesised aromatic methylglyoxal bis(guanylhydrazone) analogues demonstrated high efficacy as inhibitors of the SAMDCs. Some of these analogues exhibited Ki-values of 5 and 14 nM for the Onchocerca enzyme, a result which shows an up to 100-fold increase in specificity compared to the value of 0.47 microM for methylglyoxal bis(guanylhydrazone). These inhibitors might have potential as drug candidates against filarial worms.
Mol Biochem Parasitol 1998 Nov 30
PMID:MGBG analogues as potent inhibitors of S-adenosylmethionine decarboxylase of Onchocerca volvulus. 987 83

The gene for S-adenosylmethionine decarboxylase (AdoMetDC), a rate-limiting enzyme in the biosynthesis of polyamines, has been cloned from a Trypanosoma cruz cDNA library. The cDNA clone contains a 1.1 kb open reading frame predicted to encode a 42 kDa protein that shares 31% sequence identity to the human proenzyme. T. cruzi AdoMetDC expressed and purified from E. coli is auto-catalytically processed into two subunits of 32 kDa (alpha) and 10 kDa (beta). The catalytic activity of the purified recombinant enzyme is activated by the addition of putrescine to the reaction. To determine the effect of putrescine on the kinetics of the reaction, the velocity data collected at various substrate and putrescine concentrations were fit to the rate equation describing a non-essential activator. In the presence of fully saturating putrescine, k(cat) increases by 9-fold over the unactivated rate to 0.06 s(-1). The model derived Km for AdoMet is 0.05 mM in the absence of putrescine and the model-derived Kd for putrescine binding to free enzyme is 2.5 mM. The Km for AdoMet increases by alpha 2-fold when the enzyme is fully saturated with putrescine. Unlike human AdoMetDC, cadaverine activates the T. cruzi enzyme to a similar extent as putrescine.
Mol Biochem Parasitol 1999 Jun 25
PMID:Cloning and kinetic characterization of the Trypanosoma cruzi S-adenosylmethionine decarboxylase. 1041 38

S-adenosylmethionine decarboxylase (AdoMetDC) catalyzes the formation of decarboxylated AdoMetDC, a precursor of the polyamines spermidine and spermine. The enzyme is derived from a proenzyme by autocatalytic cleavage. We report the cloning and regulation of the gene for AdoMetDC in Neurospora crassa, spe-2, and the effect of putrescine on enzyme maturation and activity. The gene was cloned from a genomic library by complementation of a spe-2 mutant. Like other AdoMetDCs, that of Neurospora is derived by cleavage of a proenzyme. The deduced sequence of the Neurospora proenzyme (503 codons) is over 100 codons longer than any other AdoMetDC sequence available in genomic databases. The additional amino acids are found only in the AdoMetDC of another fungus, Aspergillus nidulans, a cDNA for which we also sequenced. Despite the conserved processing site and four acidic residues required for putrescine stimulation of human proenzyme processing, putrescine has no effect on the rate (t0.5 approximately 10 min) of processing of the Neurospora gene product. However, putrescine is absolutely required for activity of the Neurospora enzyme (K0.5 approximately 100 microM). The abundance of spe-2 mRNA and enzyme activity is regulated 2- to 4-fold by spermidine.
Mol Gen Genet 2000 May
PMID:Cloning and expression of the S-adenosylmethionine decarboxylase gene of Neurospora crassa and processing of its product. 1085 89

When we studied polyamine metabolism in Xenopus embryos, we cloned the cDNA for Xenopus S-adenosylmethionine decarboxylase (SAMDC), which converts SAM (S-adenosylmethionine), the methyl donor, into decarboxylated SAM (dcSAM), the aminopropyl donor, and microinjected its in vitro transcribed mRNA into Xenopus fertilized eggs. We found here that the mRNA injection induces a SAM deficient state in early embryos due to over-function of the overexpressed SAMDC, which in turn induces inhibition of protein synthesis. Such embryos developed quite normally until blastula stage, but stopped development at the early gastrula stage, due to induction of massive cell dissociation and cell autolysis, irrespective of the dosage and stage of the mRNA injection. We found that the dissociated cells were TUNEL-positive, contained fragmented nuclei with ladder-forming DNA, and furthermore, rescued completely by coinjection of Bcl-2 mRNA. Thus, overexpression of SAMDC in Xenopus embryos appeared to switch on apoptotic program, probably via inhibition of protein synthesis. Here, we briefly review our results together with those reported from other laboratories. After discussing the general importance of this newly discovered apoptotic program, we propose that the maternal program of apoptosis serves as a surveillance mechanism to eliminate metabolically severely-damaged cells and functions as a 'fail-safe' mechanism for normal development in Xenopus embryos.
Comp Biochem Physiol B Biochem Mol Biol 2000 Jun
PMID:Maternal program of apoptosis activated shortly after midblastula transition by overexpression of S-adenosylmethionine decarboxylase in Xenopus early embryos. 1087 62


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