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:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The current model of cellulose biogenesis in plants, as well as bacteria, holds that the membranous cellulose synthase complex polymerizes glucose moieties from UDP-Glc into beta-1,4-glucan chains which give rise to rigid crystalline fibrils upon extrusion at the outer surface of the cell. The distinct arrangement and degree of association of the polymerizing enzyme units presumably govern extracellular chain assembly in addition to the pattern and width of cellulose fibril deposition. Most evident for Acetobacter xylinum, polymerization and assembly appear to be tightly coupled. To date, only bacteria have been effectively studied at the biochemical and genetic levels. In A. xylinum, the cellulose synthase, composed of at least two structurally similar but functionally distinct subunits, is subject to a multicomponent regulatory system. Regulation is based on the novel nucleotide cyclic diguanylic acid, a positive allosteric effector, and the regulatory enzymes maintaining its intracellular turnover: diguanylate cyclase and Ca2(+)-sensitive bis-(3',5')-cyclic diguanylic acid (c-di-GMP) phosphodiesterase. Four genes have been isolated from A. xylinum which constitute the operon for cellulose synthesis. The second gene encodes the catalytic subunit of cellulose synthase; the functions of the other three gene products are still unknown. Exclusively an extracellular product, bacterial cellulose appears to fulfill diverse biological roles within the natural habitat, conferring mechanical, chemical, and physiological protection in A. xylinum and Sarcina ventriculi or facilitating cell adhesion during symbiotic or infectious interactions in Rhizobium and Agrobacterium species. A. xylinum is proving to be most amenable for industrial purposes, allowing the unique features of bacterial cellulose to be exploited for novel product applications.
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PMID:Cellulose biosynthesis and function in bacteria. 203 Jun 72

The two clinically important classes of antimycotic drugs, the polyenes and azoles, act on the plasma membrane of the cell. The primary modes of action are believed to be through interaction with sterols (polyenes) and alteration in sterol composition of the membrane (azoles). In this report we show that, at growth inhibitory concentrations, the polyenes (nystatin and amphotericin) and azoles (miconazole and ketoconazole) also inhibit plasma membrane enzymes. There was extensive (greater than 75%) inhibition of the Candida albicans plasma membrane enzymes ATPase, glucan synthase, adenyl cyclase and 5'-nucleotidase, when assayed in situ. The antifungals papulacandin and echinocandin, which inhibit glucan synthesis, also inhibited plasma membrane enzymes in situ; glucan synthase (greater than 90%), 5'-nucleotidase (greater than 80%) and ATPase (70-80%). Purified plasma membrane was prepared from yeast cells of C. albicans by two different techniques: concanavalin A stabilization and coating of spheroplasts with silica microbeads. In the purified plasma membrane vesicles prepared from concanavalin A the adenyl cyclase and phosphodiesterase were extensively (greater than 90%) inhibited by the three different classes of antifungal drugs; variable inhibition was observed with ATPase (70-100%). The 3',5'-cyclic phosphodiesterase of the plasma membrane purified by the microbeads method was almost completely inhibited by all of the antifungals tested and there was partial inhibition of ATPase (20-85%) and adenyl cyclase (30-90%).
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PMID:The effects of azole and polyene antifungals on the plasma membrane enzymes of Candida albicans. 283 Mar 94

An enzyme system catalyzing the synthesis of the beta 1,2-linked glucan backbone of the membrane-derived oligosaccharides of Escherichia coli from UDP-glucose has an essential requirement for the E. coli acyl carrier protein (ACP). This finding was surprising, because all other characterized functions of ACP involve acyl thioester residues linked to the phosphopantetheine moiety covalently bound to ACP. We now report that the activity of ACP in the synthesis of membrane-derived oligosaccharides is not altered by treatment with the sulfhydryl reagent N-ethylmaleimide nor by complete removal of the phosphopantetheine residue by treatment with a specific phosphodiesterase. The function of ACP in the synthesis of membrane-derived oligosaccharides is thus clearly different from that involved in lipid biosynthesis. We have nevertheless found that the same molecular species of ACP that undergo enzymic acylation with long-chain fatty acid residues also function in the synthesis of membrane-derived oligosaccharides.
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PMID:The function of acyl carrier protein in the synthesis of membrane-derived oligosaccharides does not require its phosphopantetheine prosthetic group. 347 86

Mixed membrane preparations from the coleoptiles and first leaves of young barley (Hordeum vulgare L. cv. Triumph) plants catalysed the synthesis of 55% methanol-insoluble labelled material from UDP-[U-14C]glucose, the main components of which were identified as (1,3)(1,4)-beta- and (1,3)-beta-D-glucans. The membrane preparations also catalysed the transformation of UDP-glucose into labelled low-molecular-weight products, mainly glucose (by phosphatase action), glucose-1-phosphate (by phosphodiesterase action) and glyco(phospho)lipids (by glycosyltransferase action). The formation of (1,3)(1,4)-beta-glucans, (1,3)-beta-glucans, and the other reactions competing for UDP-glucose, were monitored simultaneously and quantitatively by a novel procedure based on enzymatic analysis, thin-layer chromatography and digital autoradiography. Thus it was possible (i) to optimise conditions to obtain (1,3)(1,4)-beta-glucan synthesis or (1,3)-beta-glucan synthesis in isolation, and (ii) to study the influence of temperature, pH, cofactors, substrate concentration etc. on the (1,3)(1,4)- and (1,3)-beta-glucan synthesis reactions even when both occurred together. The synthesis of both beta-glucans was optimal at 20 degrees C. In Tris-HCl buffer, the pH optima for (1,3)(1,4)-beta-glucan synthesis and (1,3)-beta-glucan synthesis were pH 8.5 and pH 7.0, respectively. Both glucan-synthesis reactions required Mg2+: (1,3)-beta-glucan synthesis was optimal at 2 mM, whereas (1,3)(1,4)-beta-glucan synthesis continued to increase up to 200 mM Mg2+, when the ion was supplied as the sulphate. (1,3)-beta-Glucan synthesis was Ca2+ dependent and this dependence could be abolished by proteinase treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Biosynthesis of (1,3)(1,4)-beta-glucan and (1,3)-beta-glucan in barley (Hordeum vulgare L.). Properties of the membrane-bound glucan synthases. 776 40

The pseudotetrasaccharide acarbose, previously known as a potent inhibitor of intestinal alpha-glucoside hydrolases, was investigated with regard to its influence on islet lysosomal enzyme activities and the insulin secretory processes. We observed that acarbose was a potent inhibitor of mouse islet lysosomal acid glucan-1,4-alpha-glucosidase activity, EC50 approximately 5 mumol/l, as well as of acid alpha-glucosidase activity. In contrast, acarbose did not influence other lysosomal enzyme activities such as acid phosphatase and N-acetyl-beta-D-glucosaminidase. Neutral alpha-glucosidase (endoplasmic reticulum) was only moderately inhibited in homogenate and was unaffected in intact islets. Incubation of isolated mouse islets with acarbose revealed that the pseudotetrasaccharide was a strong inhibitor of glucose-induced insulin secretion, EC50 approximately 500 nmol/l, and a significant inhibition was already observed at a concentration of acarbose as low as 100 nmol/l. The acarbose analogue maltotetrose did not influence either glucose-induced insulin release or islet lysosomal enzyme activities. Further, acarbose as well as two other alpha-glucoside hydrolase inhibitors, the deoxynojirimycin derivatives miglitol and emiglitate, did not affect islet glucose oxidation at low or high glucose levels. Acarbose also inhibited insulin release induced by the sulfonylurea glibenclamide, whereas insulin secretion stimulated by the cholinergic muscarinic agonist carbachol or the phosphodiesterase inhibitor isobutylmethylxanthine was unaffected by the drug. Moreover, complementary in vivo experiments showed that pretreatment of mice with acarbose to allow for endocytosis of the compound markedly suppressed the insulin secretory response to an intravenous glucose load.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The pseudotetrasaccharide acarbose inhibits pancreatic islet glucan-1,4-alpha-glucosidase activity in parallel with a suppressive action on glucose-induced insulin release. 778 51

The first evidence that higher plants contain annexins was presented in 1989. Since that time, annexins have been purfied and characterized from a variety of plant sources. Analyses of the deduced proteins encoded by annexin cDNAs indicate that the majority of these plant annexins possess the characteristic four repeats of 70 to 75 amino acids and possess motifs proposed to be involved in Ca2+ binding. Like animal annexins, plant annexins bind Ca2+ and phospholipids and are abundant proteins, but there are indications that the number of distinct plant annexin genes may be considerably fewer than that found in animals. Regarding function, a number of studies show that various members of the annexin family of plants may play roles in secretion and/or fruit ripening, show interaction with the enzyme callose (1.3-beta-glucan) synthase, possess intrinsic nucleotide phosphodiesterase activity, bind to F-actin, and/or have peroxidase activity.
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PMID:Structures and functions of annexins in plants. 923 Sep 34

Cyclic di-GMP (c-di-GMP) is the specific nucleotide regulator of beta-1,4-glucan (cellulose) synthase in Acetobacter xylinum. The enzymes controlling turnover of c-di-GMP are diguanylate cyclase (DGC), which catalyzes its formation, and phosphodiesterase A (PDEA), which catalyzes its degradation. Following biochemical purification of DGC and PDEA, genes encoding isoforms of these enzymes have been isolated and found to be located on three distinct yet highly homologous operons for cyclic diguanylate, cdg1, cdg2, and cdg3. Within each cdg operon, a pdeA gene lies upstream of a dgc gene. cdg1 contains two additional flanking genes, cdg1a and cdg1d. cdg1a encodes a putative transcriptional activator, similar to AadR of Rhodopseudomonas palustris and FixK proteins of rhizobia. The deduced DGC and PDEA proteins have an identical motif structure of two lengthy domains in their C-terminal regions. These domains are also present in numerous bacterial proteins of undefined function. The N termini of the DGC and PDEA deduced proteins contain putative oxygen-sensing domains, based on similarity to domains on bacterial NifL and FixL proteins, respectively. Genetic disruption analyses demonstrated a physiological hierarchy among the cdg operons, such that cdg1 contributes 80% of cellular DGC and PDEA activities and cdg2 and cdg3 contribute 15 and 5%, respectively. Disruption of dgc genes markedly reduced in vivo cellulose production, demonstrating that c-di-GMP controls this process.
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PMID:Three cdg operons control cellular turnover of cyclic di-GMP in Acetobacter xylinum: genetic organization and occurrence of conserved domains in isoenzymes. 972 Dec 78

Schizophyllan is a beta-(1-->3)-D-glucan and can form a novel complex with some single-chains of DNAs. As the preceding paper revealed, the polynucleotide bound in the complex is more stable to nuclease-mediated hydrolysis than the polynucleotide itself (i.e., naked polynucleotide). This paper examined possibility to apply this complex to an antisense DNA carrier, using an in vitro (cell-free) transcription/translation assay. In this assay, we used a plasmid DNA coding a green fluorescence protein (GFP) and an antisense DNA designed to hybridize the ribosome-binding site in the GFP-coded mRNA. When the antisense DNA was administered as the complex, a lower GFP expression efficiency (or higher antisense effect) is observed over naked DNA. This is because the antisense DNA in the complex is protected from the attack of deoxyribonuclease. When exonuclease I, which specifically hydrolyzes single DNA chains, was present in the GEP assay system, the antisense effect was not changed for the complex while being weakened in the naked antisense DNA system. These results imply that the exonuclease I cannot hydrolyze the antisense DNA in the complex, while it can hydrolyze naked DNA to reduce its antisense effect.
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PMID:Antisense oligonucleotides bound in the polysaccharide complex and the enhanced antisense effect due to the low hydrolysis. 1496 45

A role for the cAMP-dependent pathway in regulation of the cell wall in the model yeast Saccharomyces cerevisiae has recently been demonstrated. In this study we report the results of a phenotypic analysis of a Candida albicans mutant, characterized by a constitutive activation of the cAMP pathway due to deletion of PDE2, the gene encoding the high cAMP-affinity phosphodiesterase. Unlike wild-type strains, this mutant has an increased sensitivity to cell wall and membrane perturbing agents such as SDS and CFW, and antifungals such as amphotericin B and flucytosine. Moreover, the mutant is characterized by an altered sensitivity and a significantly reduced tolerance to fluconazole. The mutant's membrane has around 30% higher ergosterol content and the cell wall glucan was 22% lower than in the wild-type. These cell wall and membrane changes are manifested by a considerable reduction in the thickness of the cell wall, which in the mutant is on average 60-65 nm, compared to 80-85 nm in the wild-type strains as revealed by electron microscopy. These results suggest that constitutive activation of the cAMP pathway affects cell wall and membrane structure, and biosynthesis, not only in the model yeast S. cerevisiae but also in the human fungal pathogen C. albicans.
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PMID:Deletion of PDE2, the gene encoding the high-affinity cAMP phosphodiesterase, results in changes of the cell wall and membrane in Candida albicans. 1578 49

The sequence in which a variety of enzymes and metabolites are affected by gibberellic acid after application of the hormone to aleurone layers of half seeds of barley (Hordeum vulgare var. Betzes) and half seeds of wheat (Triticum aestivum var. Gensee) was investigated. With barley aleurone layers the first hormonal effect observed was the increased secretion of soluble carbohydrate, some of which appears to be a glucan containing some beta-1,3 linkages. This was followed by increased oxygen consumption and increased secretion of ATPase, GTPase, phytase, phosphomonoesterase, phosphodiesterase, inorganic phosphate, carbohydrates other than amylase, peroxidase and amylase. Similar sequential effects were seen in wheat half seeds. Increased activity of alcohol dehydrogenase in barley seeds was elicited by the hormone but there was no effect on glucose-6-phosphate isomerase.
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PMID:A survey of the sequence of some effects of gibberellic Acid in the metabolism of cereal grains. 1665 95


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