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)

We have isolated and analyzed a pre-ferredoxin gene from Arabidopsis thaliana. This gene encodes a 148 amino acid precursor protein including a chloroplast transit peptide of 52 residues. Southern analysis shows the presence of a single copy of this ferredoxin (Fd) gene in the A. thaliana genome. Its expression is tissue-specific and positively affected by light. Response times, both to dark and light conditions, are remarkably rapid. A chimeric gene consisting of a 1.2 kb Fd promoter fragment fused to the beta-glucuronidase reporter gene was transferred to tobacco. This fusion gene is expressed in a tissue-specific way; it shows high levels of expression in green leaves, as compared to root tissue.
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PMID:Tissue-specific expression directed by an Arabidopsis thaliana pre-ferredoxin promoter in transgenic tobacco plants. 210 30

Glutamate synthase (GOGAT), a key enzyme in ammonia (NH+4) assimilation, occurs as two forms in plants: a ferredoxin-dependent form (Fd-GOGAT) and an NADH-dependent form (NADH-GOGAT). These enzymes are encoded by distinct genes as evidenced by their cDNA and deduced amino acid sequences. This paper reports the isolation and characterization of a NADH-GOGAT gene from alfalfa (Medicago sativa L.), the first GOGAT gene to be isolated from a eukaryote. RNase protection and primer extension experiments map the transcription start site of NADH-GOGAT to nearly identical positions. The transcribed region of this gene, 12,214 bp, is comprised of 22 exons separated by 21 introns. The 2.7 kbp region 5' from the translation initiation site confers nodule-specific reporter gene activity when used in a chimeric beta-glucuronidase (GUS) construct and transformed into Lotus corniculatus and Medicago sativa. Both infected and uninfected cells display GUS activity. The abundance of NADH-GOGAT transcripts increases substantially in developing nodules of plants infected with effective rhizobia. However, this increase is not observed when nodules are induced by a variety of ineffective rhizobial strains. Thus, unlike many other plant genes involved in root nodule NH+4 assimilation, high levels of NADH-GOGAT expression are strictly associated with effective nodules indicating that NADH-GOGAT plays a central role in the functioning of effective root nodules. An alfalfa Fd-GOGAT PCR product showing greater than 85% identity to maize Fd-GOGAT was isolated and used to investigate the contribution of this enzyme to NH+4 assimilation in nodules. Fd-GOGAT mRNA was abundant in leaves and cotyledons but was not detected in alfalfa root nodules. Fd-GOGAT in alfalfa does not appear to play a significant role in symbiotic N2 fixation.
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PMID:Alfalfa NADH-dependent glutamate synthase: structure of the gene and importance in symbiotic N2 fixation. 755 Mar 73

Messenger RNA primary structures responsible for translational efficiency of a photosystem I gene, psaDb, of Nicotiana sylvestris were studied using a transgenic tobacco system. The entire 5'-leader (23 base pairs) with the first four amino acid codons of the protein coding region was fused in frame with the beta-glucuronidase (GUS) gene under the control of the 35 S promoter of cauliflower mosaic virus (CaMV). This construct (CaMV::psaDb-GUS') was introduced into tobacco. GUS activity and GUS mRNA levels were determined for individual transformants, revealing that the insertion of the psaDb sequence greatly enhanced the GUS activity relative to GUS mRNA abundance. The GUS activity/GUS mRNA was 14 times higher in the CaMV::psaDb-GUS' transformants than in the control CaMV::GUS' transformants. The high GUS activity/GUS mRNA of the CaMV::psaDb-GUS' transformants was reduced 20-fold when 13 bases within the psaDb leader were altered. These 13 bases are common to the leaders of an Arabidopsis ferredoxin gene and the psaDb gene of N. sylvestris. Since GUS proteins encoded by these chimeric GUS genes have identical amino acid sequences, these results indicate that the 5'-leader of the psaDb mRNA contains a translational enhancer element.
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PMID:5'-leader of a photosystem I gene in Nicotiana sylvestris, psaDb, contains a translational enhancer. 775 89

A genomic clone encoding the precursor of wheat leaf ferredoxin has been isolated and characterised. The uninterrupted PetF gene encodes a polypeptide of 143 amino acid residues, consisting of an N-terminal presequence of 46 amino acid residues and a mature polypeptide of 97 amino acid residues. Southern blot analysis suggests that six copies of the PetF gene are present in the wheat haploid genome. Northern blot analysis has shown that the genes are both developmentally and light regulated in wheat seedlings and provides evidence that a circadian rhythm regulates the steady-state levels of ferredoxin transcripts. The intact wheat gene and several chimeric constructs, containing portions of the 5'-upstream region fused to the beta-glucuronidase reporter gene, have been introduced into tobacco plants, but levels of beta-glucuronidase activity above background were not detected, suggesting that the 5'-upstream region is unable to function as a promoter in tobacco plants.
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PMID:Developmental, circadian and light regulation of wheat ferredoxin gene expression. 788 19

Ferredoxin is a nuclear-encoded protein that is involved in a variety of electron transfer reactions in both photosynthetic and non-photosynthetic plastids. We show here that the expression of the ferredoxin A gene (FedA) in Arabidopsis thaliana is light-regulated, with its mRNA level increased 4.5-fold by transfer of dark-grown seedlings to white light for 3 h. A portion of this light regulation is mediated by phytochrome through a very low fluence type of response. In addition, it is likely that another photoreceptor(s) is also involved. The FedA promoter confers a light- and tissue-regulated expression pattern when fused to the beta-glucuronidase (GUS) and luciferase reporter genes, indicating that the gene is transcriptionally regulated. No evidence of cis-acting light-regulatory elements within the 5' untranslated leader region of the gene was detected. Nevertheless, elements within this leader are required for full activity since its deletion reduces expression both in the light and dark by 25-fold. This region includes a sequence, ACAAAA, which is also present in the 5' untranslated leader of the other three ferredoxin leaders that have been sequenced and in the leaders of 31 other plant genes or about 8% of all plant genes in the GenBank database. In addition to mediating light regulation, the FedA promoter also directs GUS expression in aerial tissues at 70-fold higher levels than in roots. GUS activity staining in aerial tissues is observed in both photosynthetic and non-photosynthetic cells. These data indicate that the FedA promoter also carries the information for expression of this gene in a highly tissue- and cell-specific manner.
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PMID:Promoter and leader regions involved in the expression of the Arabidopsis ferredoxin A gene. 840 2

We describe a genomic DNA segment from spinach that bears part of the single-copy gene for ferredoxin-NADP(+)-oxidoreductase (FNR) including a 3.4 kb promoter sequence. Dissection of this DNA segment and its analysis in GUS (beta-glucuronidase) gene fusions in transgenic tobacco demonstrated that the promoter differs in structure from all other promoters for thylakoid protein genes studied to date. Two regions with light-responsive elements were identified. One is located within the first 118 bp upstream of the transcription initiation site. A second fragment covering nucleotide positions -220 to -119 is capable of conferring light-dependent GUS gene expression on two different minimal promoters. The latter fragment binds a transacting factor in gel-shift assays. None of the fragments carries cis elements known from other genes to be involved in light-controlled expression. Comparison of the light responsiveness of GUS gene fusions controlled by the -753/+231 and -118/+231 regions indicates that they respond differentially to phytochrome-dependent signals and that their expression in tobacco is not restricted to tissue with functional chloroplasts.
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PMID:Characterization of the promoter from the single-copy gene encoding ferredoxin-NADP(+)-oxidoreductase from spinach. 845 61

The effect of iron on ferredoxin I specific mRNA levels was studied in the cyanobacterial strains Synechococcus sp. PCC 7942 (Anacystis nidulans R2) and Anabaena sp. PCC 7937 (Anabaena variabilis ATCC 29413). In both strains addition of iron to iron-limited cells resulted in a rapid increase in ferredoxin mRNA levels. To investigate the possible role of the ferredoxin promoter in iron regulation, a vector for promoter analysis in Synechococcus PCC 7942 strain R2-PIM9 was constructed, which contains the ferredoxin promoter fused to the gene encoding beta-glucuronidase (GUS) as reporter. Neither the Synechococcus nor the Anabaena ferredoxin promoter was able to direct iron-regulated GUS activity in Synechococcus R2-PIM9, indicating that transcription initiation is not responsible for the iron-dependent ferredoxin mRNA levels. Determination of the half-life of the ferredoxin transcript in iron-supplemented and iron-limited cells revealed that, in both strains, the ferredoxin transcript is much more stable in iron-supplemented cells than in iron-limited cells. These results lead to the conclusion that in these strains, iron-regulated expression of the ferredoxin I gene is mediated via differential mRNA stability.
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PMID:Iron-dependent stability of the ferredoxin I transcripts from the cyanobacterial strains Synechococcus species PCC 7942 and Anabaena species PCC 7937. 845 69

Investigations of phytochrome mutants of Arabidopsis suggested that the expression of chalcone synthase (chs) and anthocyanin accumulation is predominantly controlled by phytochrome A. To test the functionality of phytochrome A and B at the molecular level recombinant, yeast-derived phytochrome-phycocyanobilin adducts (phyA, phyB) and oat phytochrome A (phyA) were microinjected into etiolated aurea tomato seedlings. Subsequent to microinjection anthocyanin and chlorophyll accumulation was monitored as well as beta-glucuronidase (GUS) expression mediated by light-regulated promoters (chs, chlorophyll a/b binding protein (lhcb1) and ferredoxin NADP+ oxidoreductase (fnn). Microinjection of phyA under white light conditions caused anthocyanin and chlorophyll accumulation and mediated chs-GUS, lhcb 1-GUS and fnr-GUS expression. Microinjection of phyB under identical conditions induced chlorophyll accumulation and mediated lhcb 1-GUS and fnr-GUS expression but neither anthocyanin accumulation nor chs-GUS expression were observed. The characterization of Arabidopsis phytochrome mutants and the microinjection experiments suggested that phyB cannot induce the accumulation of juvenile anthocyanin. Microinjections under far-red light conditions demonstrated that phyA can act independently of other photoreceptors. By contrast, phyB injections under red light conditions indicated that phyB needs interactions with other photoreceptors to mediate a rapid and efficient de-etiolation signal.
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PMID:Functional analysis of yeast-derived phytochrome A and B phycocyanobilin adducts. 889 41

psaDb is a nuclear gene encoding the ferredoxin-binding subunit of photosystem I in Nicotiana sylvestris. The organization of the light-responsive cis-elements of psaDb was studied using transgenic tobacco plants. Three types of psaDb chimeric constructs were created: (1) a 5' upstream fragment of psaDb transcriptionally fused with the beta-glucuronidase (GUS) gene, and a series of its 5' deletion derivatives, (2) the transcribed region of psaDb driven by the cauliflower mosaic virus (CaMV) 35S promoter, and (3) the 5' terminal 35 bases (the entire leader, +1 to +23, and the initiation codon context, +24 to +35) of the psaDb mRNA translationally fused with a GUS reporter gene under the operation of the CaMV 35S promoter. Light-responsiveness of these fusions in transgenic plants was examined by GUS assay and primer extension analysis. The results indicate that the light-responsive elements (LRE) of psaDb are located both upstream (-170 to +24) and within (+1 to +861) the transcribed region. The internal LRE is utilized in etiolated seedings but not in green leaves. The leader and initiation codon context construct (+1 to +35) did not show any light-response under the conditions tested. Therefore, it is likely that a combination of the upstream and internal LREs generates the complex light-responsive and tissue-specific regulation of this gene. This study also revealed that psaDb has adjacent activator (-267 to -254) and repressor (-253 to -234) regions for basal transcriptional activity; the former contains the ACGT binding motif recognized by many plant bZIP proteins, and the latter has the R3 decamer motif found in several photosystem I-related genes.
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PMID:Light-responsive elements of the tobacco PSI-D gene are located both upstream and within the transcribed region. 930 Oct 80

Photosynthetic organisms acclimate to long term changes in the environmental light quality by an adjustment of their photosystem stoichiometry to maintain photosynthetic efficiency. By using light sources that predominantly excite either photosystem I (PSI) or photosystem II (PSII), we studied the effects of excitation imbalances between both photosystems on nuclear PSI gene transcription in transgenic tobacco seedlings with promoter::beta-glucuronidase gene fusions. Shifts from PSI to PSII light sources (and vice versa) induced changes in the reduction/oxidation state of intersystem redox components, and acclimation of tobacco seedlings to such changes were monitored by changes in chlorophyll a/b ratios and in vivo chlorophyll a fluorescence. The ferredoxin-NADP(+)-oxidoreductase gene promoter did not respond to these treatments, those from the genes for subunits PsaD and PsaF of PSI are activated by a reduction signal, and the plastocyanin promoter responded to both reduction and oxidation signals. Additional experiments with photosynthetic electron transport inhibitors 3-(3',4'-dichlorophenyl)-1,1'-dimethyl urea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone demonstrated that the redox state of the plastoquinone pool controls the activity of the plastocyanin promoter, whereas subunit PsaD and PsaF gene transcription is regulated by other photosynthesis-derived signals. Thus, the expression of nuclear-encoded PSI genes is controlled by diverse light quality-dependent redox signals from the plastids during photosystem stoichiometry adjustment.
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PMID:A novel mechanism of nuclear photosynthesis gene regulation by redox signals from the chloroplast during photosystem stoichiometry adjustment. 1146 91


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