Showing papers on "Cyclase published in 2010"
TL;DR: The novel enzymatic activity and stress resistance together point toward a role for YybT in stress signaling and response.
224 citations
TL;DR: Identification of a new class of lanthionine synthetases provides insight into the mechanism and evolution of cyclic peptide biosynthesis.
Abstract: Lantibiotic synthetases are remarkable biocatalysts generating conformationally constrained peptides with a variety of biological activities by repeatedly utilizing two simple posttranslational modification reactions: dehydration of Ser/Thr residues and intramolecular addition of Cys thiols to the resulting dehydro amino acids. Since previously reported lantibiotic synthetases show no apparent homology with any other known protein families, the molecular mechanisms and evolutionary origin of these enzymes are unknown. In this study, we present a novel class of lanthionine synthetases, termed LanL, that consist of three distinct catalytic domains and demonstrate in vitro enzyme activity of a family member from Streptomyces venezuelae. Analysis of individually expressed and purified domains shows that LanL enzymes install dehydroamino acids via phosphorylation of Ser/Thr residues by a protein kinase domain and subsequent elimination of the phosphate by a phosphoSer/Thr lyase domain. The latter has sequence homology with the phosphothreonine lyases found in various pathogenic bacteria that inactivate host mitogen activated protein kinases. A LanC-like cyclase domain then catalyzes the addition of Cys residues to the dehydro amino acids to form the characteristic thioether rings. We propose that LanL enzymes have evolved from stand-alone protein Ser/Thr kinases, phosphoSer/Thr lyases, and enzymes catalyzing thiol alkylation. We also demonstrate that the genes for all three pathways to lanthionine-containing peptides are widespread in Nature. Given the remarkable efficiency of formation of lanthionine-containing polycyclic peptides and the latter's high degree of specificity for their cognate cellular targets, it is perhaps not surprising that (at least) three distinct families of polypeptide sequences have evolved to access this structurally and functionally diverse class of compounds.
193 citations
TL;DR: Although farnesol induces the accumulation of intracellular reactive oxygen species (ROS), ROS generation is not necessary for the induction of catalase (Cat1)-mediated oxidative-stress resistance.
Abstract: Farnesol, a Candida albicans cell-cell signaling molecule that participates in the control of morphology, has an additional role in protection of the fungus against oxidative stress. In this report, we show that although farnesol induces the accumulation of intracellular reactive oxygen species (ROS), ROS generation is not necessary for the induction of catalase (Cat1)-mediated oxidative-stress resistance. Two antioxidants, α-tocopherol and, to a lesser extent, ascorbic acid effectively reduced intracellular ROS generation by farnesol but did not alter farnesol-induced oxidative-stress resistance. Farnesol inhibits the Ras1-adenylate cyclase (Cyr1) signaling pathway to achieve its effects on morphology under hypha-inducing conditions, and we demonstrate that farnesol induces oxidative-stress resistance by a similar mechanism. Strains lacking either Ras1 or Cyr1 no longer exhibited increased protection against hydrogen peroxide upon preincubation with farnesol. While we also observed the previously reported increase in the phosphorylation level of Hog1, a known regulator of oxidative-stress resistance, in the presence of farnesol, the hog1/hog1 mutant did not differ from wild-type strains in terms of farnesol-induced oxidative-stress resistance. Analysis of Hog1 levels and its phosphorylation states in different mutant backgrounds indicated that mutation of the components of the Ras1-adenylate cyclase pathway was sufficient to cause an increase of Hog1 phosphorylation even in the absence of farnesol or other exogenous sources of oxidative stress. This finding indicates the presence of unknown links between these signaling pathways. Our results suggest that farnesol effects on the Ras-adenylate cyclase cascade are responsible for many of the observed activities of this fungal signaling molecule.
98 citations
TL;DR: The Mg2+ binding in a C-terminal EF-hand contributes to neither retGC1 docking with the cyclase nor its subsequent activation in the light, but is specifically required for switching thecyclase off in the conditions of dark adaptation by binding Ca2+.
Abstract: Photon absorption by photoreceptors activates hydrolysis of cGMP, which shuts down cGMP-gated channels and decreases free Ca2+ concentrations in outer segment Suppression of Ca2+ influx through the cGMP channel by light activates retinal guanylyl cyclase through guanylyl cyclase activating proteins (GCAPs) and thus expedites photoreceptors recovery from excitation and restores their light sensitivity GCAP1 and GCAP2, two ubiquitous among vertebrate species isoforms of GCAPs that activate retGC during rod response to light, are myristoylated Ca2+/Mg2+-binding proteins of the EF-hand superfamily They consist of one non-metal binding EF-hand-like domain and three other EF-hands, each capable of binding Ca2+ and Mg2+ In the metal binding EF-hands of GCAP1, different point mutations can selectively block binding of Ca2+ or both Ca2+ and Mg2+ altogether Activation of retGC at low Ca2+ (light adaptation) or its inhibition at high Ca2+ (dark adaptation) follows a cycle of Ca2+/Mg2+ exchange in GCAPs, rather than release of Ca2+ and its binding by apo-GCAPs The Mg2+ binding in two of the EF-hands controls docking of GCAP1 with retGC1 in the conditions of light adaptation and is essential for activation of retGC Mg2+ binding in a C-terminal EF-hand contributes to neither retGC1 docking with the cyclase nor its subsequent activation in the light, but is specifically required for switching the cyclase off in the conditions of dark adaptation by binding Ca2+ The Mg2+/Ca2+ exchange in GCAP1 and 2 operates within different range of intracellular Ca2+ concentrations and provides a two-step activation of the cyclase during rod recovery
97 citations
TL;DR: Levels of AC6 mRNA, the most highly expressed AC isoform in the inner medulla, inversely correlate with fluid intake, which determines inner medullary cAMP formation and AQP2 phosphorylation and trafficking, the absence of which causes nephrogenic diabetes insipidus.
Abstract: Arginine vasopressin (AVP) enhances water reabsorption in the renal collecting duct by vasopressin V2 receptor (V2R)-mediated activation of adenylyl cyclase (AC), cAMP-promoted phosphorylation of aquaporin-2 (AQP2), and increased abundance of AQP2 on the apical membrane. Multiple isoforms of adenylate cyclase exist, and the roles of individual AC isoforms in water homeostasis are not well understood. Here, we found that levels of AC6 mRNA, the most highly expressed AC isoform in the inner medulla, inversely correlate with fluid intake. Moreover, mice lacking AC6 had lower levels of inner medullary cAMP, reduced abundance of phosphorylated AQP2 (at both serine-256 and serine-269), and lower urine osmolality than wild-type mice. Water deprivation or administration of the V2R agonist dDAVP did not increase urine osmolality of AC6-deficient mice to the levels of wild-type mice. Furthermore, AC6-deficient mice lacked dDAVP-promoted inner medullary cAMP formation and phosphorylation of serine-269 and had attenuated increases in both phosphorylation of serine-256 and apical membrane AQP2 trafficking. In summary, AC6 expression determines inner medullary cAMP formation and AQP2 phosphorylation and trafficking, the absence of which causes nephrogenic diabetes insipidus.
84 citations
TL;DR: Two isoforms of guanylate cyclase, GC1 and GC2 encoded by G UCY2D and GUCY2F, are responsible for the replenishment of cGMP in photoreceptors after exposure to light and are required for the normal kinetics of photoreceptor sensitivity and recovery.
Abstract: Two isoforms of guanylate cyclase, GC1 and GC2 encoded by GUCY2D and GUCY2F, are responsible for the replenishment of cGMP in photoreceptors after exposure to light. Both are required for the normal kinetics of photoreceptor sensitivity and recovery, although disease mutations are restricted to GUCY2D. Recessive mutations in this gene cause the severe early-onset blinding disorder Leber congenital amaurosis whereas dominant mutations result in a later onset less severe cone-rod dystrophy. Cyclase activity is regulated by Ca(2+) which binds to the GC-associated proteins, GCAP1 and GCAP2 encoded by GUCA1A and GUCA1B, respectively. No recessive mutations in either of these genes have been reported. Dominant missense mutations are largely confined to the Ca(2+)-binding EF hands of the proteins. In a similar fashion to the disease mechanism for the dominant GUCY2D mutations, these mutations generally alter the sensitivity of the cyclase to inhibition as Ca(2+) levels rise following a light flash.
69 citations
TL;DR: Both EF and CyaA have a rather broad substrate specificity and exhibit cytidylyl and uridylyL cyclase activity, and both cCMP and cUMP may contribute to toxin actions.
Abstract: Cyclic adenosine 3′,5′-monophosphate (cAMP) and cyclic guanosine 3′,5′-monophosphate (cGMP) are second messengers for numerous mammalian cell functions. The natural occurrence and synthesis of a third cyclic nucleotide (cNMP), cyclic cytidine 3′,5′-monophosphate (cCMP), is a matter of controversy, and almost nothing is known about cyclic uridine 3′,5′-monophosphate (cUMP). Bacillus anthracis and Bordetella pertussis secrete the adenylyl cyclase (AC) toxins edema factor (EF) and CyaA, respectively, weakening immune responses and facilitating bacterial proliferation. A cell-permeable cCMP analogue inhibits human neutrophil superoxide production. Here, we report that EF and CyaA also possess cytidylyl cyclase (CC) and uridylyl cyclase (UC) activity. CC and UC activity was determined by a radiometric assay, using [α-32P]CTP and [α-32P]UTP as substrates, respectively, and by a high-performance liquid chromatography method. The identity of cNMPs was confirmed by mass spectrometry. On the basis of available crys...
60 citations
TL;DR: While the isolated catalytic domain of Bordetella pertussis AC was spherical and hydrated, it underwent a significant elongation as well as compaction and dehydration upon calmodulin interaction, and a model for the structural transition between the cal modulin-free and calmod insulin-bound AC is proposed.
Abstract: Bordetella pertussis, the causative agent of whooping cough, secretes among various toxins an adenylate cyclase (CyaA) that displays a unique mechanism of cell invasion, which involves a direct translocation of its N-terminal catalytic domain (AC, 400 residues) across the plasma membrane of the eukaryotic targeted cells. Once into the cytosol, AC is activated by endogenous calmodulin and produces toxic amounts of cAMP. The structure of AC in complex with the C-terminal part of calmodulin has recently been determined. However, as the structure of the catalytic domain in the absence of calmodulin is still lacking, the molecular basis of AC activation by calmodulin remains largely unknown. To characterize this activation mechanism, we investigated here the biophysical properties of the isolated catalytic domain in solution with or without calmodulin. We found that calmodulin triggered only minor modifications of the protein secondary and tertiary structure but had a pronounced effect on the hydrodynamic prop...
57 citations
TL;DR: This review focuses on the structure and function of the ROS-GC subfamily present in the mammalian retinal neurons: photoreceptors and inner layers of the Retinal neurons.
Abstract: Vertebrate phototransduction depends on the reciprocal relationship between two-second messengers, cyclic GMP and Ca2+. The concentration of both is reciprocally regulated including the dynamic synthesis of cyclic GMP by a membrane bound guanylate cyclase. Different from hormone receptor guanylate cyclases, the cyclases operating in phototransduction are regulated by the intracellular Ca2+-concentration via small Ca2+-binding proteins. Based on the site of their expression and their Ca2+ modulation, this sub-branch of the cyclase family was named sensory guanylate cyclases, of which the retina specific forms are named ROS-GCs (rod outer segment guanylate cyclases). This review focuses on the structure and function of the ROS-GC subfamily present in the mammalian retinal neurons: photoreceptors and inner layers of the retinal neurons. Portions and excerpts of the review are from a previous chapter (Curr Top Biochem Res 6:111–144, 2004).
50 citations
TL;DR: A combination of substitutions within the pore‐forming and acylation‐bearing domain ablates selectively the cell‐permeabilizing activity of CyaA, which employs a mechanism of AC enzyme domain translocation across cellular membrane that avoids passage across the cytolytic pore formed by toxin oligomers.
Abstract: The adenylate cyclase toxin-haemolysin of Bordetella (CyaA) targets CD11b(+) myeloid phagocytes and translocates across their cytoplasmic membrane an adenylate cyclase (AC) enzyme that catalyses conversion of cytosolic ATP into cAMP In parallel, CyaA acts as a cytolysin forming cation-selective pores, which permeabilize cell membrane and eventually provoke cell lysis Using cytolytic activity, potassium efflux and patch-clamp assays, we show that a combination of substitutions within the pore-forming (E570Q) and acylation-bearing domain (K860R) ablates selectively the cell-permeabilizing activity of CyaA At the same time, however, the capacity of such mutant CyaA to translocate the AC domain across cytoplasmic membrane into cytosol of macrophage cells and to elevate cellular cAMP concentrations remained intact Moreover, the combination of E570Q+K860R substitutions suppressed the residual cytolytic activity of the enzymatically inactive CyaA/OVA/AC(-) toxoid on CD11b-expressing monocytes, while leaving unaffected the capacity of the mutant toxoid to deliver in vitro a reporter CD8(+) T cell epitope from ovalbumin (OVA) to the cytosolic pathway of dendritic cells for MHC class I-restricted presentation and induce in vivo an OVA-specific cytotoxic T cell response CyaA, hence, employs a mechanism of AC enzyme domain translocation across cellular membrane that avoids passage across the cytolytic pore formed by toxin oligomers
50 citations
TL;DR: It is proposed that improved stress acclimation during continuous light in comparison with light-dark growth increases the capacity to prevent photooxidation by excess tetrapyrrole precursors and lowers the susceptibility to secondary photodynamic damage.
Abstract: Mg protoporphyrin monomethylester (MgProtoME) cyclase catalyzes isocyclic ring formation to form divinyl protochlorophyllide. The CHL27 protein is part of the cyclase complex. Defi ciency of CHL27 has been previously reported to compromise photosynthesis and nuclear gene expression. In a comprehensive analysis of different CHL27 antisense tobacco lines grown under different light conditions, the physiological consequences of gradually reduced CHL27 expression on the tetrapyrrole biosynthetic pathway were explored. Excessive amounts of MgProtoME, the substrate of the cyclase reaction, accumulated in response to the reduced CHL27 content. Moreover, 5-aminolevulinic acid (ALA) synthesis, Mg chelatase and Mg protoporphyrin methyltransferase activities were reduced in transgenic plants. Compared with growth under continuous light exposure, the CHL27 -defi cient plants showed a stronger reduction in Chl content, cell death and leaf necrosis during diurnal light/dark cycles. This photooxidative phenotype correlated with a rapidly increasing MgProtoME steady-state level at the beginning of each light period. In contrast, the same transformants grown under continuous light exposure possessed a permanently elevated amount of MgProtoME. Its lower phototoxicity correlated with increased activities of ascorbate peroxidase and catalase, and a higher amount of reduced ascorbate. It is proposed that improved stress acclimation during continuous light in comparison with light–dark growth increases the capacity to prevent photooxidation by excess tetrapyrrole precursors and lowers the susceptibility to secondary photodynamic damage.
TL;DR: Molecular and biochemical analyses showed that heterologously expressed GC-G protein, specifically the C-terminal cyclase domain, was directly stimulated by bicarbonate in both in vivo cellular cGMP accumulation assays in human embryonic kidney-293T cells and in vitro GC assays with a purified recombinant protein containing the GC domain.
Abstract: GC (guanylate cyclase)-G is the most recently identified member of the receptor GC family However, the regulation of its activity and protein expression in the mammalian olfactory system remains unclear In the present study, we used a GC-G-specific antibody to validate that the GC-G protein is expressed in Grueneberg ganglion neurons, a newly recognized olfactory subsystem co-expressing other cGMP signalling components such as the cGMP-regulated PDE2A (phosphodiesterase 2A) and the cGMP-gated ion channel CNGA3 (cyclic nucleotide-gated cation channel α-3) Further molecular and biochemical analyses showed that heterologously expressed GC-G protein, specifically the C-terminal cyclase domain, was directly stimulated by bicarbonate in both in vivo cellular cGMP accumulation assays in human embryonic kidney-293T cells and in vitro GC assays with a purified recombinant protein containing the GC domain In addition, overexpression of GC-G in NG108 neuronal cells resulted in a CO2-dependent increase in cellular cGMP level that could be blocked by treatment with acetazolamide, an inhibitor of carbonic anhydrases, which implies that the stimulatory effect of CO2 requires its conversion to bicarbonate Together, our data demonstrate a novel CO2/bicarbonate-dependent activation mechanism for GC-G and suggest that GC-G may be involved in a wide variety of CO2/bicarbonate-regulated biological processes such as the chemosensory function in Grueneberg ganglion neurons
TL;DR: Detailed phylogenetic and sequence analysis is presented, coupled with experiments both in vitro and in vivo, that suggest that this ajudazol TE promotes formation of the isochromanone ring, a novel reaction for this type of domain.
Abstract: The ajudazols are antifungal secondary metabolites produced by a hybrid polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS) multienzyme "assembly line" in the myxobacterium Chondromyces crocatus Cm c5. The most striking structural feature of these compounds is an isochromanone ring system; such an aromatic moiety is only known from two other complex polyketides, the electron transport inhibitor stigmatellin and the polyether lasalocid. The cyclization and aromatization reactions in the stigmatellin pathway are presumed to be catalyzed by a cyclase domain located at the end of the PKS, while the origin of the lasalocid benzenoid ring remains obscure. Notably, the ajudazol biosynthetic machinery does not incorporate a terminal cyclase, but instead a variant thioesterase (TE) domain. Here we present detailed phylogenetic and sequence analysis, coupled with experiments both in vitro and in vivo, that suggest that this TE promotes formation of the isochromanone ring, a novel reaction for this type of domain. As the ajudazol TE has homologues in several other secondary-metabolite pathways, these results are likely to be generalizable.
TL;DR: The data herein reveal plant carotenoid cyclases to be novel enzymes that combine characteristics of non-metal-assisted terpene cyclases with those attributes typically found in flavoenzymes that catalyze reactions, with no net redox, such as type 2 isopentenyl diphosphate isomerase.
Abstract: The later steps of carotenoid biosynthesis involve the formation of cyclic carotenoids. The reaction is catalyzed by lycopene β-cyclase (LCY-B), which converts lycopene into β-carotene, and by capsanthin-capsorubin synthase (CCS), which is mainly dedicated to the synthesis of κ-cyclic carotenoids (capsanthin and capsorubin) but also has LCY-B activity. Although the peptide sequences of plant LCY-Bs and CCS contain a putative dinucleotide-binding motif, it is believed that these two carotenoid cyclases proceed via protic activation and stabilization of resulting carbocation intermediates. Using pepper (Capsicum annuum) CCS as a prototypic carotenoid cyclase, we show that the monomeric protein contains one noncovalently bound flavin adenine dinucleotide (FAD) that is essential for enzyme activity only in the presence of NADPH, which functions as the FAD reductant. The reaction proceeds without transfer of hydrogen from the dinucleotide cofactors to β-carotene or capsanthin. Using site-directed mutagenesis, amino acids potentially involved in the protic activation were identified. Substitutions of alanine, lysine, and arginine for glutamate-295 in the conserved 293-FLEET-297 motif of pepper CCS or LCY-B abolish the formation of β-carotene and κ-cyclic carotenoids. We also found that mutations of the equivalent glutamate-196 located in the 194-LIEDT-198 domain of structurally divergent bacterial LCY-B abolish the formation of β-carotene. The data herein reveal plant carotenoid cyclases to be novel enzymes that combine characteristics of non-metal-assisted terpene cyclases with those attributes typically found in flavoenzymes that catalyze reactions, with no net redox, such as type 2 isopentenyl diphosphate isomerase. Thus, FAD in its reduced form could be implicated in the stabilization of the carbocation intermediate.
TL;DR: Amide derivatives of 8 and 12 preserved the inhibitory activity of parent compound 3, which provided a reasonable starting point for further structure-activity-relationship (SAR) studies on related compounds.
Patent•
02 Jun 2010
TL;DR: In this article, a method for the biocatalytic production of ambroxan by means of a polypeptide having the activity of a homofarnesol-ambroxan cyclase was described.
Abstract: The invention relates to a method for the biocatalytic production of ambroxan by means of a polypeptide having the activity of a homofarnesol-ambroxan cyclase and representing a novel class of enzymes.
TL;DR: It is reported that treatment of cells with geldanamycin, an inhibitor of heat shock protein 90 (Hsp90), led to effective attenuation of morphine-induced adenylate cyclase sensitization, indicating that Hsp90 is a new pharmacological target for the suppression of adenYLate cyclases sensitization induced by chronic morphine treatment.
TL;DR: A protein with both cyclase and phosphodiesterase activities is characterized and it is demonstrated that it contributes to secretion of the extracellular polysaccharide matrix, an important step in early biofilm formation.
Abstract: Cyclic-di-GMP signaling is used by many bacteria to control biofilm formation. As biofilm formation is an important survival strategy for many bacteria, the synthesis and degradation of cyclic-di-GMP is tightly regulated by enzymes containing domains with conserved GGDEF and EAL sequence motifs, respectively. In this report we characterize a protein with both cyclase and phosphodiesterase activities and demonstrate that it contributes to secretion of the extracellular polysaccharide matrix, an important step in early biofilm formation.
TL;DR: Evidence is presented that autophosphorylation does not regulate GC1 activity, in contrast to phosphorylation of other members of this cyclase family.
TL;DR: In Synechocystis cGMP levels are of similar magnitude as those of cAMP and deletion of the cya2 gene markedly reduced the amount of c GMP without affecting cAMP, which points toward the existence of a true bacterial cG MP-signaling pathway.
Abstract: Production of cGMP in bacteria has been studied since the early 1970s. From the beginning on it proved to be a challenging topic. In Escherichia coli the cGMP levels were two orders of magnitude lower than the corresponding cAMP levels. Furthermore, no specific cGMP receptor protein was identified in the bacterium and a physiological role of cGMP in the bacterium was not substantiated. Consequently in 1977, compelling evidence was given that cGMP is a by-product of E. coli adenylate cyclase in vivo. This may be the reason why also work on cGMP in other bacteria like Bacillus licheniformis and Caulobacter crescentus was not pursued any further. However, recent study on cGMP and guanylate cyclase in the cyanobacterium Synechocysis PCC 6803 brought cGMP signaling in bacteria back to attention. In Synechocystis cGMP levels are of similar magnitude as those of cAMP and deletion of the cya2 gene markedly reduced the amount of cGMP without affecting cAMP. A few months ago the Cya2 gene product has been biochemically and structurally characterized. It behaves as a specific guanylate cyclase in vitro and a single amino acid substitution transforms the enzyme into a specific adenylate cyclase. These data point toward the existence of a true bacterial cGMP-signaling pathway, which needs to be explored and established by future experiments.
TL;DR: It is shown here that ACT stimulates a raft-mediated calcium influx, through its cAMP production activity, that activates PKA, which in turn activates calcium channels with L-type properties, suggesting a common mechanism, independent of the toxin receptor.
TL;DR: The crystal structure of the RtcA-AMP intermediate reveals the mechanism of nucleotidyl transfer and illuminates how the four alpha2/beta4 domains contribute to substrate binding and catalysis.
TL;DR: Bovine retina appears to be more sensitive to the stimulatory effect of H2S donors on cyclic nucleotide production than its porcine counterpart indicating that species differences exist in the magnitude of this response.
Abstract: Hydrogen sulfide (H(2)S) has been reported to exert pharmacological effects on neural and non-neural tissues from several mammalian species. In the present study, we examined the role of the intracellular messenger, cyclic AMP in retinal response to H(2)S donors, sodium hydrosulfide (NaHS) and sodium sulfide (Na(2)S) in cows and pigs. Isolated bovine and porcine neural retinae were incubated in oxygenated Krebs buffer solution prior to exposure to varying concentrations of NaHS, Na(2)S or the diterpene activator of adenylate cyclase, forskolin. After incubation at different time intervals, tissue homogenates were prepared for cyclic AMP assay using a well established methodology. In isolated bovine and porcine retinae, the combination of both phosphodiesterase inhibitor, IBMX (2 mM) and forskolin (10 microM) produced a synergistic increase (P < 0.001) in cyclic AMP concentrations over basal levels. NaHS (10 nM-100 microM) produced a time-dependent increase in cyclic AMP concentrations over basal levels which reached a maximum at 20 min in both bovine and porcine retinae. At this time point, both NaHS and Na(2)S (10 nM-100 microM) caused a significant (P < 0.05) dose-dependent increase in cyclic AMP levels in bovine and porcine retinae. For instance, NaHS (100 nM) elicited a four-fold and three-fold increase in cyclic AMP concentrations in bovine and porcine retinae respectively whilst higher concentrations of Na(2)S (100 microM) produced a much lesser effect in both species. In bovine and porcine retinae, the effects caused by forskolin (10 microM) on cyclic AMP production were not potentiated by addition of low or high concentrations of both NaHS and Na(2)S. We conclude that H(2)S donors can increase cyclic AMP production in isolated neural retinae from cows and pigs. Bovine retina appears to be more sensitive to the stimulatory effect of H(2)S donors on cyclic nucleotide production than its porcine counterpart indicating that species differences exist in the magnitude of this response. Furthermore, effects produced by forskolin on cyclic AMP formation were not additive with those elicited by H(2)S donors suggesting that these agents may share a common mechanism in their action on the adenylyl cyclase pathway.
Patent•
12 Feb 2010TL;DR: In this paper, a plant cell with a heterologous expression cassette and a polynucleotide encoding a PYR/PYL receptor polypeptide was characterized by the presence of one or both of a polyketide cyclase domain 2 (PF10604) or a Polyketide Cyclase domain 1 (PF03364).
Abstract: This disclosure relates to plant cells comprising a heterologous expression cassette, the expression cassette comprising a heterologous promoter operably linked to a polynucleotide encoding a PYR/PYL receptor polypeptide, wherein the PYR/PYL receptor polypeptide is characterized by the presence of one or both of a polyketide cyclase domain 2 (PF10604) or a polyketide cyclase domain 1 (PF03364), and wherein the PYR/PYL receptor polypeptide comprises SEQ ID NO:102, wherein the plant cell has improved stress tolerance compared to a plant cell lacking the expression cassette.
TL;DR: The observation that glyoxylate bypass enzymes are derepressed in cyaB mutant indicates the involvement of cAMP in the repression of aceB and aceA, and suggests that adenylate cyclase plays an essential role in the acetate metabolism of C. glutamicum.
Abstract: Genome analysis of C. glutamicum ATCC 13032 has showed one putative adenylate cyclase gene, cyaB (cg0375) which encodes membrane protein belonging to class III adenylate cyclases. To characterize the function of cyaB, a deletion mutant was constructed, and the mutant showed decreased level of intracellular cyclic AMP compared to that of wild-type. Interestingly, the cyaB mutant displayed growth defect on acetate medium, and this effect was reversed by complementation with cyaB gene. Similarly, it showed growth defect on glucose-acetate mixture minimal medium, and the utilization of glucose was retarded in the presence of acetate. The deletion mutant retained the activity of glyoxylate bypass enzymes. Additionally, the mutant could grow on ethanol but not on propionate medium. The data obtained from this study suggests that adenylate cyclase plays an essential role in the acetate metabolism of C. glutamicum, even though detailed regulatory mechanisms involving cAMP are not yet clearly defined. The observation that glyoxylate bypass enzymes are derepressed in cyaB mutant indicates the involvement of cAMP in the repression of aceB and aceA.
TL;DR: A panel of structurally related substituted 4‐phenylpiperazines with nanomolar affinity and selectivity at D3 dopamine receptors has been synthesized and it is shown that the heterocyclic amide moiety appears to be the pivotal structural element determining the intrinsic efficacy of these D3 receptor selective compounds.
Abstract: A panel of structurally related substituted 4-phenylpiperazines with nanomolar affinity and selectivity at D3 dopamine receptors has been synthesized. Compounds in which a heterocyclic (2-phenyl pyridyl, 3-phenyl pyridyl, benzothiophene, or benzofuran) moiety is adjacent to the amide was varied and/or a double bond (trans-butenyl) replaced the four-carbon aliphatic chain linking the arylamide with the 4-phenylpiperazine moiety were compared for (a) affinity at human D2 and D3 dopamine receptors, (b) intrinsic efficacy using an adenylyl cyclase inhibition assay, and (c) intrinsic efficacy using a mitogenic assay. All 16 compounds were (a) more efficacious for the D3 receptor cyclase inhibition assay than for the D3 receptor mitogenic assay and (b) exhibited the same or greater efficacy at D3 compared to D2 receptor (with the exception of one compound). Although the heterocyclic amide moiety appears to be the pivotal structural element determining the intrinsic efficacy of our D3 receptor selective compounds, the magnitude of the efficacy is modulated by the (a) substituent(s) on the phenyl piperazine and (b) the saturation of the four-carbon chain that links the arylamide and the phenylpiperazine. In addition, our ligands are functionally selective, because they can have differing intrinsic efficacies for the cyclase inhibition and the mitogenic activation signaling pathways. Compounds that are essentially full agonists at the cyclase assay appear to be only partial agonists in the mitogenic assay and compounds that are partial agonists in our cyclase assay are partial agonists or antagonists in the mitogenic assay.
TL;DR: Through ten-generation investigation, the capability of cAMP production of A302 was found to be stable and the special activities of key enzymes in A302, which influenced the cAMP biosynthesis, was analyzed.
TL;DR: It is found that the NO coordination state, NO dissociation, and enzyme activation were significantly affected by the presence of a tyrosine in the distal heme pocket; however, the stability of the reduced porphyrin and the proteins affinity for oxygen were unaltered, suggesting that atypical sGCs stabilize O2 binding by a hydrogen bonding network involving tyrosines and glutamine.
TL;DR: Downregulation of polyamines inhibits cardiomyocyte hypertrophy, which is closely related to [Ca2+]i and the NO/PKG-I pathway.
Abstract: Background: Polyamines and nitric oxide (NO) have been involved in the pathogenesis of cardiac hypertrophy. NO can regulate cardiac ion channels by direct actions on G-proteins and adenyl cyclase. The
Patent•
03 Dec 2010
TL;DR: In this article, a method to prevent, control, and treat a lipid metabolism disorder, a biliary disorder, cardiovascular disease, obesity or an endocrine disorder by administering at least one agonist of guanalyte cyclase receptor either alone or in combination with a compound typically used to treat the disorder and or with an inhibitor of cGMP-dependent phosphodieasterases.
Abstract: This invention also provides a method to prevent, control, and treata lipid metabolism disorder, a biliary disorder, cardiovascular disease, obesity or an endocrine disorder by administering at least one agonist of guanalyte cyclase receptor either alone or in combination with a compound typically used to treat the disorder and or with an an inhibitor of cGMP-dependent phosphodieasterases.