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:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mutagenicity of 2-hydroxylamino-4-nitrotoluene (2HA4NT), 4-hydroxylamino-2-nitrotoluene (4HA2NT), 2-hydroxylamino-6-nitrotoluene (2HA6NT) or 4-acetylamino-2-hydroxylaminotoluene (4AA2HAT) towards Salmonella typhimurium strains TA98 and TA100 was investigated in the absence and presence of uridine-5'-diphosphoglucuronic acid (UDPGA), acetyl CoA or 3'-phosphoadenosine-5'-phosphosulfate (PAPS) systems, or S9 mix. None of the hydroxylaminonitrotoluenes (2HA4NT, 4HA2NT or 2HA6NT) were mutagenic in both strains while 4AA2HAT was a base-pair substitution mutagen in the UDPGA and PAPS systems. The indirect mutagenic activity was markedly decreased by omission of microsomal fraction (MCF) or UDPGA from the UDPGA system and by addition of beta-glucuronidase to the system. Similarly, the mutagenic activity was markedly decreased either when 105000 X g supernatant fluid (S105), adenosine triphosphate (ATP) or Na2SO4 was omitted from the PAPS system or when pentachlorophenol (PCP) or aryl sulphatase was added to the system. Moreover, the mutagenic activity in either system was markedly decreased by the addition of glutathione (GSH). These results suggested that two esterifications with glucuronic acid and sulfuric acid may play an important role in the appearance of mutagenic activity of 4AA2HAT.
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PMID:Mutagenicity of some hydroxylaminotoluene derivatives towards Salmonella typhimurium in esterification systems. 355 29

Although the coordinated biosynthesis of isoprenoid compounds is thought to be essential to the normal processes of plant growth and development, the mechanisms that regulate the mevalonate pathway in plants are not well understood. As the first committed step in the pathway, the conversion of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) to mevalonic acid by HMG CoA reductase and the regulation of the genes encoding this enzyme have been implicated in the network that controls isoprenoid biosynthesis in higher plants. Using histochemical staining for beta-glucuronidase, as well as conventional RNA hybridization analysis, the temporal and spatial regulation of HMG1, one of the genes encoding HMG CoA reductase in the crucifer Arabidopsis thaliana, has been characterized. Furthermore, the HMG1 promoter is shown to be differentially responsive to illumination in different organs, and promoter activation by light deprivation is confined primarily to immature leaves. In contrast, expression of the HMG1 gene in roots is confined to the elongation zone and is not responsive to illumination. Light-mediated regulation of HMG1 expression is shown to be an organ-autonomous response that depends on direct illumination, and environmental cues regarding light do not appear to be exchanged between different organs in Arabidopsis. These studies reveal several new features of HMG1 regulation, and indicate that the high levels of HMG CoA reductase expression detected in immature leaves may be primarily attributed to the dark-induced expression of HMG1, and that HMG1 is expressed at low levels throughout the plant in response to light. Thus, environmental cues interact with the developmental program to define the pattern of HMG1 gene expression in Arabidopsis.
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PMID:Light modulates the spatial patterns of 3-hydroxy-3-methylglutaryl coenzyme A reductase gene expression in Arabidopsis thaliana. 910 38

Young pine seedlings respond to environmental stress by induced synthesis of pinosylvin, a stilbene phytoalexin. Heartwood of pine trees is characterized by a high content of pinosylvin. The formation of pinosylvin from cinnamoyl-CoA and three molecules malonyl-CoA catalysed by pinosylvin synthase is typical of the genus Pinus. Its enzyme activity not detectable in unstressed seedlings is substantially increased upon application of stimuli like UV-light or infection with the phytopathogenic fungus Botrytis cinerea. A genomic DNA library was screened with pinosylvin synthase cDNA pSP-54 as a probe. Ten clones were isolated and grouped into five subclasses according to the size of their introns. After subcloning into plasmid T7T3, four different members of the five gene subclasses were characterized by sequencing. Emphasis was put on isolating various promoters and analyzing and comparing their responsiveness. The amino acid sequences deduced from genes PST-1, PST-2, PST-3 and PST-5 shared an overall identity of more than 95%. In gene PST-5, the putative translation start site ATG was replaced by CTG. While promoter regions near the TATAA box were almost identical PST-1, PST-2 and PST-3, further upstream sequences differed substantially. Differences in promoter strength were analysed both in transgenic tobacco plants and by transient expression in tobacco protoplasts. Constructs used contained the bacterial beta-glucuronidase under the control of the promoters of pine genes PST-1, PST-2 and PST-3. Upon treatment with UV light or fungal elicitor, the promoter of PST-1 showed highest responsiveness and led to tissue-specific expression in vascular bundles. The data suggest that in pine the gene product of PST-1 is responsible for both the stress response in seedlings and pinosylvin formation in the heartwood.
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PMID:Characterization of a pine multigene family containing elicitor-responsive stilbene synthase genes. 1008 Jun 90

The AC-rich motif, Pal-box, is an important cis-acting element for gene expression involved in phenylpropanoid biosynthesis. A cDNA clone (Ntlim1) encoding a Pal-box binding protein was isolated by Southwestern screening. The deduced amino acid sequence is highly similar to the members of the LIM protein family that contain a zinc finger motif. Moreover, Ntlim1 had a specific DNA binding ability and transiently activated the transcription of a beta-glucuronidase reporter gene driven by the Pal-box sequence in tobacco protoplasts. The transgenic tobacco plants with antisense Ntlim1 showed low levels of transcripts from some key phenylpropanoid pathway genes such as phenylalanine ammonia-lyase, hydroxycinnamate CoA ligase and cinnamyl alcohol dehydrogenase. Furthermore, a 27% reduction of lignin content was observed in the transgenic tobacco with antisense Ntlim1.
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PMID:Functional analysis of tobacco LIM protein Ntlim1 involved in lignin biosynthesis. 1084 46

The first step of peroxisomal fatty acid beta-oxidation is catalyzed by a family of acyl-CoA oxidase isozymes with distinct fatty acyl-CoA chain-length specificities. Here we identify a new acyl-CoA oxidase gene from Arabidopsis (AtACX3) following the isolation of a promoter-trapped mutant in which beta-glucuronidase expression was initially detected in the root meristem. In acx3 mutant seedlings medium-chain acyl-CoA oxidase activity was reduced by 95%, whereas long- and short-chain activities were unchanged. Despite this reduction in activity lipid catabolism and seedling development were not perturbed. AtACX3 was cloned and expressed in Escherichia coli. The recombinant enzyme displayed medium-chain acyl-CoA substrate specificity. Analysis of beta-glucuronidase activity in acx3 revealed that, in addition to constitutive expression in the root axis, AtACX3 is also up-regulated strongly in the hypocotyl and cotyledons of germinating seedlings. This suggests that beta-oxidation is regulated predominantly at the level of transcription in germinating oilseeds. After the discovery of AtACX3, the Arabidopsis acyl-CoA oxidase gene family now comprises four isozymes with substrate specificities that encompass the full range of acyl-CoA chain lengths that exist in vivo.
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PMID:Promoter trapping of a novel medium-chain acyl-CoA oxidase, which is induced transcriptionally during Arabidopsis seed germination. 1091 60

Lignin is a complex phenolic plant polymer that is essential for mechanical support, defense, and water transport in higher plants. The AC-rich motif, Pal-box is an important cis-acting element for gene expression in phenylpropanoid biosynthesis. We isolated a cDNA clone (Ntlim1) encoding a Pal-box binding protein by Southwestern screening. The deduced amino acid sequence of Ntlim1 is highly similar to members of the LIM protein family that contain a zinc finger motif. Moreover, Ntlim1 had a specific DNA-binding ability and transiently activated transcription of a beta-glucuronidase reporter gene driven by the Pal-box sequence. The results of transient expression assays with tobacco cultured cells showed that fusion proteins between GFP and Ntlim1 can enter nuclei. Transgenic tobacco plants with antisense Ntlim1 showed low levels of transcripts from some key phenylpropanoid pathway genes such as phenylalanine ammonia-lyase, hydroxycinnamate CoA ligase and cinnamyl alcohol dehydrogenase. Furthermore, a greater than 20% reduction in lignin content was observed in transgenic tobacco with antisense Ntlim1.
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PMID:Transcriptional control of lignin biosynthesis by tobacco LIM protein. 1143 Sep 87

Lysophosphatidyl acyltransferase (LPAT) is a pivotal enzyme controlling the metabolic flow of lysophosphatidic acid into different phosphatidic acids in diverse tissues. We examined putative LPAT genes in Arabidopsis thaliana and characterized two related genes that encode the cytoplasmic LPAT. LPAT2 is the lone gene that encodes the ubiquitous and endoplasmic reticulum (ER)-located LPAT. It could functionally complement a bacterial mutant with defective LPAT. LPAT2 and 3 synthesized in recombinant bacteria and yeast possessed in vitro enzyme activity higher on 18:1-CoA than on 16:0-CoA. LPAT2 was expressed ubiquitously in diverse tissues as revealed by RT-PCR, profiling with massively parallel signature sequencing, and promoter-driven beta-glucuronidase gene expression. LPAT2 was colocalized with calreticulin in the ER by immunofluorescence microscopy and subcellular fractionation. LPAT3 was expressed predominately but more actively than LPAT2 in pollen. A null allele (lpat2) having a T-DNA inserted into LPAT2 was identified. The heterozygous mutant (LPAT2/lpat2) had minimal altered vegetative phenotype but produced shorter siliques that contained normal seeds and remnants of aborted ovules in a 1:1 ratio. Results from selfing and crossing it with the wild type revealed that lpat2 caused lethality in the female gametophyte but not the male gametophyte, which had the redundant LPAT3. LPAT2-cDNA driven by an LPAT2 promoter functionally complemented lpat2 in transformed heterozygous mutants to produce the lpat2/lpat2 genotype. LPAT3-cDNA driven by the LPAT2 promoter could rescue the lpat2 female gametophytes to allow fertilization to occur but not to full embryo maturation. Two other related genes, putative LPAT4 and 5, were expressed ubiquitously albeit at low levels in diverse organs. When they were expressed in bacteria or yeast, the microbial extract did not contain LPAT activity higher than the endogenous LPAT activity. Whether LPAT4 and 5 encode LPATs remains to be elucidated.
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PMID:Ubiquitous and endoplasmic reticulum-located lysophosphatidyl acyltransferase, LPAT2, is essential for female but not male gametophyte development in Arabidopsis. 1577 83

The conversion of UDP-glucuronate to glucuronate, usually thought to proceed by way of glucuronate 1-phosphate, is a site for short-term regulation of vitamin C synthesis by metyrapone and other xenobiotics in isolated rat hepatocytes. Our purpose was to explore the mechanism of this effect in cell-free systems. Metyrapone and other xenobiotics stimulated, by approximately threefold, the formation of glucuronate from UDP-glucuronate in liver extracts enriched with ATP-Mg, but did not affect the formation of glucuronate 1-phosphate from UDP-glucuronate or the conversion of glucuronate 1-phosphate to glucuronate. This and other data indicated that glucuronate 1-phosphate is not an intermediate in glucuronate formation from UDP-glucuronate, suggesting that this reaction is catalysed by a 'UDP-glucuronidase'. UDP-glucuronidase was present mainly in the microsomal fraction, where its activity was stimulated by UDP-N-acetylglucosamine, known to stimulate UDP-glucuronosyltransferases by enhancing the transport of UDP-glucuronate across the endoplasmic reticulum membrane. UDP-glucuronidase and UDP-glucuronosyltransferases displayed similar sensitivities to various detergents, which stimulated at low concentrations and generally inhibited at higher concentrations. Substrates of glucuronidation inhibited UDP-glucuronidase activity, suggesting that the latter is contributed by UDP-glucuronosyltransferase(s). Inhibitors of beta-glucuronidase and esterases did not affect the formation of glucuronate, arguing against the involvement of a glucuronidation-deglucuronidation cycle. The sensitivity of UDP-glucuronidase to metyrapone and other stimulatory xenobiotics was lost in washed microsomes, even in the presence of ATP-Mg, but it could be restored by adding a heated liver high-speed supernatant or CoASH. In conclusion, glucuronate formation in liver is catalysed by a UDP-glucuronidase which is closely related to UDP-glucuronosyltransferases. Metyrapone and other xenobiotics stimulate UDP-glucuronidase by antagonizing the inhibition exerted, presumably indirectly, by a combination of ATP-Mg and CoASH.
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PMID:Glucuronate, the precursor of vitamin C, is directly formed from UDP-glucuronate in liver. 1668 37

Lignin is an important biopolymer that is deposited in secondary cell walls of plant cells (e.g., tracheary elements) and in response to stresses such as wounding. Biosynthesis of lignin monomers occurs via the phenylpropanoid pathway, in which the enzyme 4-coumarate:CoA ligase (4CL) plays a key role by catalyzing the formation of hydroxycinnamoyl-CoA esters, subsequently reduced to the corresponding monolignols (hydroxycinnamoyl alcohols). 4CL is encoded by a family of four genes in Arabidopsis thaliana (At4CL1-At4CL4), which are developmentally regulated and co-expressed with other phenylpropanoid genes. We investigated in detail the wound-induced expression of At4CL1-At4CL4, and found that At4CL1 and At4CL2 mRNA accumulation follows biphasic kinetics over a period of 72 h, while At4CL4 expression is rapidly activated for a period of at least 12 h before declining. In order to localize cis-regulatory elements involved in the developmental and wound-induced regulation of the At4CL gene family members, At4CL promoter-beta-glucuronidase (GUS) reporter gene fusions were constructed and transferred into Arabidopsis plants. Analysis of these plants revealed that the promoter fragments direct discrete and distinct patterns of expression, some of which did not recapitulate expected patterns of wound-induced expression. The locations of regulatory elements associated with the At4CL2 gene were investigated in detail using a series of transgenic Arabidopsis plants containing promoter fragments and parts of the transcribed region of the gene fused to GUS. Positive and negative regulatory elements effective in modulating developmental expression or wound responsiveness of the gene were located both in the promoter and transcribed regions of the At4CL2 gene.
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PMID:Multiple cis-regulatory elements regulate distinct and complex patterns of developmental and wound-induced expression of Arabidopsis thaliana 4CL gene family members. 1673 63

4-coumarate::CoA ligase (4CL) gene family members are involved in channeling carbon flow into branch pathways of phenylpropanoid metabolism. Transgenic Arabidopsis plants containing the At4CL1 or At4CL2 promoter fused to the beta-glucuronidase (GUS) reporter gene show developmentally regulated GUS expression in the xylem tissues of the root and shoot. To identify regulatory genes involved in the developmental regulation of At4CL and other phenylpropanoid-specific genes, we generated ethyl methyl sulfate mutagenized populations of At4CL1::GUS and At4CL2::GUS transgenic lines and screened approximately 16,000 progeny for reduced or altered GUS expression. Several lines with reproducible patterns of reduced GUS expression were identified. However, the GUS-expression phenotype segregated in a non-Mendelian manner in all of the identified lines. Also, GUS expression was restored by 5-azacytidine (aza) treatment, suggesting inhibitory DNA methylation of the transgene. Southern analysis confirmed DNA methylation of the proximal promoter sequences of the transgene only in the mutant lines. In addition, retransformation of At4CL::GUS lines with further At4CL promoter constructs enhanced the GUS-silencing phenotype. Taken together, these results suggest that the isolated mutants are epimutants. Apparently, two different modes of silencing were engaged in the At4CL1::GUS and At4CL2::GUS silenced lines. While silencing in the seedlings of the At4CL1::GUS lines was root specific in seedlings, it affected all organs in the At4CL2::GUS lines. Also, At4CL1::GUS transgene silencing was confined to the transgene but At4CL2::GUS silencing extended to the endogenous At4CL2 gene. Organ-specific silencing of the At4CL1::GUS transgene cannot be explained by current models in the literature.
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PMID:Genetic analysis and epigenetic silencing of At4CL1 and At4CL2 expression in transgenic Arabidopsis. 1700 3


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