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)

In Arabidopsis thaliana, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA) but the gene does not include any sequence corresponding to the consensus ABA-responsive element (ABRE), RYACGTGGYR, in its promoter region. The cis-regulatory region of the rd22 promoter was identified by monitoring the expression of beta-glucuronidase (GUS) activity in leaves of transgenic tobacco plants transformed with chimeric gene fusions constructed between 5'-deleted promoters of rd22 and the coding region of the GUS reporter gene. A 67-bp nucleotide fragment corresponding to positions -207 to -141 of the rd22 promoter conferred responsiveness to dehydration and ABA on a non-responsive promoter. The 67-bp fragment contains the sequences of the recognition sites for some transcription factors, such as MYC, MYB, and GT-1. The fact that accumulation of rd22 mRNA requires protein synthesis raises the possibility that the expression of rd22 might be regulated by one of these trans-acting protein factors whose de novo synthesis is induced by dehydration or ABA. Although the structure of the RD22 protein is very similar to that of a non-storage seed protein, USP, of Vicia faba, the expression of the GUS gene driven by the rd22 promoter in non-stressed transgenic Arabidopsis plants was found mainly in flowers and bolted stems rather than in seeds.
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PMID:Identification of a cis-regulatory region of a gene in Arabidopsis thaliana whose induction by dehydration is mediated by abscisic acid and requires protein synthesis. 777 45

An Arabidopsis cDNA (Atmyb2) that contains a sequence that encodes a transcription factor, which is a homolog of MYB, was cloned from a cDNA library prepared from dehydrated Arabidopsis rosette plants. A gene (Atmyb2) corresponding to the Atmyb2 cDNA was also cloned and its nucleotide sequence was determined. RNA gel blot analysis showed that the Atmyb2 mRNA was induced by dehydration and disappeared upon rehydration. The Atmyb2 mRNA also accumulated upon salt stress and with the onset of treatment with abscisic acid. A beta-glucuronidase reporter gene driven by the Atmyb2 promoter was induced by dehydration and salt stress in transgenic Arabidopsis plants. These observations indicate that Atmyb2 is responsive to dehydration at the transcriptional level. The putative protein (ATMYB2) encoded by Atmyb2 has 274 amino acids, a molecular mass of 32 kD, and a putative DNA binding domain that shows considerable homology to plant MYB-related proteins, such as maize C1. A fusion protein that included ATMYB2 was expressed in Escherichia coli, and it bound specifically to oligonucleotides that contained a consensus MYB recognition sequence (TAACTG), such as is found in the simian virus 40 enhancer and the maize bronze-1 promoter. Binding was sequence specific, as indicated by a gel mobility shift experiment. These results suggest that a MYB-related transcription factor is involved in the regulation of genes that are responsive to water stress in Arabidopsis.
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PMID:An Arabidopsis myb homolog is induced by dehydration stress and its gene product binds to the conserved MYB recognition sequence. 831 38

In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA) and requires protein biosynthesis for ABA-dependent gene expression. Previous experiments established that a 67-bp DNA fragment of the rd22 promoter is sufficient for dehydration- and ABA-induced gene expression and that this DNA fragment contains two closely located putative recognition sites for the basic helix-loop-helix protein MYC and one putative recognition site for MYB. We have carefully analyzed the 67-bp region of the rd22 promoter in transgenic tobacco plants and found that both the first MYC site and the MYB recognition site function as cis-acting elements in the dehydration-induced expression of the rd22 gene. A cDNA encoding a MYC-related DNA binding protein was isolated by DNA-ligand binding screening, using the 67-bp region as a probe, and designated rd22BP1. The rd22BP1 cDNA encodes a 68-kD protein that has a typical DNA binding domain of a basic region helix-loop-helix leucine zipper motif in MYC-related transcription factors. The rd22BP1 protein binds specifically to the first MYC recognition site in the 67-bp fragment. RNA gel blot analysis revealed that transcription of the rd22BP1 gene is induced by dehydration stress and ABA treatment, and its induction precedes that of rd22. We have reported a drought- and ABA-inducible gene that encodes the MYB-related protein ATMYB2. In a transient transactivation experiment using Arabidopsis leaf protoplasts, we demonstrated that both the rd22BP1 and ATMYB2 proteins activate transcription of the rd22 promoter fused to the beta-glucuronidase reporter gene. These results indicate that both the rd22BP1 (MYC) and ATMYB2 (MYB) proteins function as transcriptional activators in the dehydration- and ABA-inducible expression of the rd22 gene.
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PMID:Role of arabidopsis MYC and MYB homologs in drought- and abscisic acid-regulated gene expression. 936 19

To identify DNA sequences of the Arabidopsis thaliana chalcone synthase gene (CHS) concerned with induction by UV-B and UV-A/blue light, AtCHS promoter constructions were assayed by transient expression in protoplasts prepared from two different lines of cultured A. thaliana cells. The protoplasts responded similarly to A. thaliana leaf tissue in light-dependent CHS transcript accumulation. The reporter enzyme beta-glucuronidase (GUS) was used to monitor light-responsive promoter activity. A 1972 bp promoter conferred UV-B and UV-A/blue light induction of GUS activity. Deletion to 164 bp resulted in reduced promoter strength but retention of responsiveness to UV-B and UV-A/blue light. Further deletion abolished transcriptional activity. The 164 bp promoter contains sequences closely resembling LRUPcCHS, (light-responsive unit of the Petroselinum crispum CHS promoter). This A. thaliana CHS promoter region, designated LRUAtCHS, was sufficient to confer UV-B and UV-A/blue light responsiveness to a heterologous core promoter. Mutation of sequences in LRUAtCHS corresponding to the ACGT element and the MYB recognition element of LRUPcCHS resulted in inactivation of the 164 bp and 335 bp promoter deletions. However, the mutant 668 bp promoter retained residual UV-B and UV-A/blue light-induced expression, indicating the presence of additional functional sequences upstream of -335. Mutation of a single G-box-like sequence around -442 had no effect on light responsiveness, indicating that it does not function in light regulation of this promoter. Since no difference in responsiveness to UV-B and UV-A/blue light was observed with any promoter variant, we conclude that the two phototransduction pathways regulate transcription factors which interact with common promoter elements. The results from-our analysis of a A. thaliana light-responsive promoter will facilitate the study of light-dependent gene regulation by genetic means in Arabidopsis thaliana.
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PMID:Identification of UV/blue light-response elements in the Arabidopsis thaliana chalcone synthase promoter using a homologous protoplast transient expression system. 952 7

We have undertaken a systematic reverse genetic approach to understand R2R3-MYB gene function in Arabidopsis. Here, we report the functional characterization of MYB61 based on the phenotype of three independent insertion alleles. Wide-ranging phenotype screens indicated that MYB61 mutants were deficient in seed mucilage extrusion upon imbibition. This phenotype was expressed in the sporophytic tissues of the seed. Deposition and extrusion of the principal component of the mucilage, a relatively unbranched rhamnogalacturonan, were reduced in the MYB61 mutant seed coats. Additional defects in the maturation of the testa epidermal cells suggested a potential deficiency in extracellular secretion in myb61 lines. Consistent with a proposed role in testa development, reverse transcription-polymerase chain reaction analysis showed the highest MYB61 expression in siliques, which was localized to the seed coat by a beta-glucuronidase (GUS) reporter gene fusion. Lower levels of GUS expression were detected in developing vascular tissue. Parallel analysis of the ttg1-1 mutant phenotype indicated that this mutant showed more severe developmental defects than myb61 and suggested that MYB61 may function in a genetic pathway distinct from that of TTG1. The transient nature of seed epidermal characteristics in the ttg1-1 mutant suggested that TTG1 was required for maintenance rather than initiation of testa epidermal differentiation. Germination and seedling establishment were compromised in the myb61 and ttg1-1 mutants under conditions of reduced water potential, suggesting a function for Arabidopsis seed mucilage during germination in dry conditions.
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PMID:MYB61 is required for mucilage deposition and extrusion in the Arabidopsis seed coat. 1175 87

In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA). We reported previously that MYC and MYB recognition sites in the rd22 promoter region function as cis-acting elements in the drought- and ABA-induced gene expression of rd22. bHLH- and MYB-related transcription factors, rd22BP1 (renamed AtMYC2) and AtMYB2, interact specifically with the MYC and MYB recognition sites, respectively, in vitro and activate the transcription of the beta-glucuronidase reporter gene driven by the MYC and MYB recognition sites in Arabidopsis leaf protoplasts. Here, we show that transgenic plants overexpressing AtMYC2 and/or AtMYB2 cDNAs have higher sensitivity to ABA. The ABA-induced gene expression of rd22 and AtADH1 was enhanced in these transgenic plants. Microarray analysis of the transgenic plants overexpressing both AtMYC2 and AtMYB2 cDNAs revealed that several ABA-inducible genes also are upregulated in the transgenic plants. By contrast, a Ds insertion mutant of the AtMYC2 gene was less sensitive to ABA and showed significantly decreased ABA-induced gene expression of rd22 and AtADH1. These results indicate that both AtMYC2 and AtMYB2 proteins function as transcriptional activators in ABA-inducible gene expression under drought stress in plants.
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PMID:Arabidopsis AtMYC2 (bHLH) and AtMYB2 (MYB) function as transcriptional activators in abscisic acid signaling. 1250 22

Transcript levels of the Arabidopsis R2R3-AtMYB102 transcription factor gene, previously named AtM4, are rapidly induced by osmotic stress or abscisic acid (ABA) treatment. Reporter gene expression studies revealed that in addition, wounding is required for full induction of the gene. Histochemical analysis showed a local beta-glucuronidase induction around the wounding site, especially in veins. In ABA-treated plants, wounding-induced beta-glucuronidase activity could be mimicked by the wound signaling compound methyl jasmonate. In silico studies of the AtMYB102 promoter sequence and its close homolog AtMYB74 demonstrated several conserved putative stress regulatory elements such as an ABA-responsive element, its coupling element 1 (CE1), and a W box. Interestingly, further studies showed that the 5'-untranslated region is essential for the osmotic stress and wounding induced expression of the AtMYB102 gene. This 5'-untranslated region contains putative conserved regulatory elements such as a second W box and an overlapping MYB-binding element. These studies suggest that AtMYB102 expression depends on and integrates signals derived from both wounding and osmotic stress.
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PMID:Integration of wounding and osmotic stress signals determines the expression of the AtMYB102 transcription factor gene. 1285 23

The functions of the vast majority of genes encoding R2R3 MYB domain proteins remain unknown. The closely related MYB33 and MYB65 genes of Arabidopsis thaliana have high sequence similarity to the barley (Hordeum vulgare) GAMYB gene. T-DNA insertional mutants were isolated for both genes, and a myb33 myb65 double mutant was defective in anther development. In myb33 myb65 anthers, the tapetum undergoes hypertrophy at the pollen mother cell stage, resulting in premeiotic abortion of pollen development. However, myb33 myb65 sterility was conditional, where fertility increased both under higher light or lower temperature conditions. Thus, MYB33/MYB65 facilitate, but are not essential for, anther development. Neither single mutant displayed a phenotype, implying that MYB33 and MYB65 are functionally redundant. Consistent with functional redundancy, promoter-beta-glucuronidase (GUS) fusions of MYB33 and MYB65 gave identical expression patterns in flowers (sepals, style, receptacle, anther filaments, and connective but not in anthers themselves), shoot apices, and root tips. By contrast, expression of a MYB33:GUS translational fusion in flowers was solely in young anthers (consistent with the male sterile phenotype), and no staining was seen in shoot meristems or root tips. A microRNA target sequence is present in the MYB genes, and mutating this sequence in the MYB33:GUS fusion results in an expanded expression pattern, in tissues similar to that observed in the promoter-GUS lines, implying that the microRNA target sequence is restricting MYB33 expression. Arabidopsis transformed with MYB33 containing the mutated microRNA target had dramatic pleiotrophic developmental defects, suggesting that restricting MYB33 expression, especially in the shoot apices, is essential for proper plant development.
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PMID:The Arabidopsis GAMYB-like genes, MYB33 and MYB65, are microRNA-regulated genes that redundantly facilitate anther development. 1572 75

The best known property of plant proteinase inhibitor II (PIN2) genes is their wound-inducible expression in leaves and constitutive expression in flowers. Here we show by promoter analysis in transgenic plants and in situ reverse transcription-PCR (RT-PCR) analysis that SaPIN2b, a member of the PIN2 gene family of nightshade (Solanum americanum), is also constitutively expressed in glandular trichomes. SaPIN2b promoter and its deletions were cloned and fused upstream of beta-glucuronidase (GUS) to transform the nightshade and tobacco (Nicotiana tabacum) plants. Histochemical staining assays indicated that SaPIN2b:GUS was expressed constitutively in glandular trichomes, predominantly in the gland cells, of both transgenic nightshade and tobacco plants. Constitutive expression of SaPIN2b in glandular trichomes was further confirmed by liquid phase in situ RT-PCR analysis of nightshade leaves. Deletion analysis from the 5' end of the SaPIN2b promoter revealed that separate regulatory elements control SaPIN2b expression in gland cells and stalk cells of glandular trichomes. Fluorometric GUS assays showed that SaPIN2b:GUS expression was significantly increased in transgenic plant leaves after mechanical wounding or methyl jasmonate treatment. The SaPIN2b promoter sequence contains six MYB-binding motifs and an L1 box that are involved in trichome differentiation and development. Overexpression of SaPIN2b in tobacco resulted in a significant increase in glandular trichome density and promotion of trichome branching. These results suggest that, as well as being an induced defensive protein of the well-known PIN2 family, SaPIN2b could also play roles in trichome-based defense by functioning as a constitutive component of trichome chemical defense and/or by regulating the development of glandular trichomes.
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PMID:The nightshade proteinase inhibitor IIb gene is constitutively expressed in glandular trichomes. 1692 66

Type I lipid transfer proteins (LTPs) are basic, 9-kDa cystein-rich proteins believed to be involved in plant defense mechanisms. A 2,100-bp fragment containing the coding region of Vitis vinifera lipid transfer protein 1 (VvLTP1) and 1,420-bp of its promoter region was isolated by screening a grape genomic library. In silico analysis revealed several putative, defense-related, cis-regulatory elements such as W- and MYB-boxes, involved in the binding of WRKY and MYB transcription factors, respectively. The 5'-truncated versions of the VvLTP1 promoter were generated, cloned in front of the beta-glucuronidase (GUS) reporter gene, and introduced in tobacco plants and grapevine cell suspensions using Agrobacterium spp. Single MYB- and the W-boxes identified on the 0.250-kbp fragment were sufficient to induce GUS activity in transgenic tobacco plants after transient expression of MYB and WRKY. Ergosterol, a nonspecific fungal elicitor, induced GUS activity in transgenic grapevine cell suspensions transformed with the 1,420- and 750-bp promoter containing a palindromic arrangement of two W-boxes but not the 650- or 250-bp fragment, where only one W-box was present. Moreover, ergosterol triggered WRKY, VvLTP1, and stilbene synthase gene expression in grape plantlets and enhanced protection against Botrytis cinerea. The molecular basis of ergosterol-induced protection is discussed.
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PMID:Molecular basis of ergosterol-induced protection of grape against botrytis cinerea: induction of type I LTP promoter activity, WRKY, and stilbene synthase gene expression. 1702 74


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