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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)

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.
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PMID:Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus. 926 31

At-P5R, a gene encoding the last enzyme of the proline (Pro) biosynthetic pathway in Arabidopsis thaliana, is developmentally regulated. To characterize the cis elements responsible for this developmental regulation, a series of 5' deletions of the At-P5R promoter were transcriptionally fused to a beta-glucuronidase (GUS)-coding region and transformed into Arabidopsis. The complete promoter of At-P5R directs strong GUS activity in root tips, the shoot meristem, guard cells, hydathodes, pollen grains, ovules, and developing seeds, all of which contain rapidly dividing cells and/or are undergoing changes in osmotic potential. This expression pattern is consistent with the function of Pro as an energy, nitrogen, and carbon source and as an osmoticum in response to dehydration. Promoters longer than 212 base pairs (bp) showed the same expression pattern, whereas those shorter than 143 bp did not direct any detectable GUS activity in any organs. This suggests that a 69-bp promoter region located between -212 and -143 bp is necessary to establish the tissue-specific expression of At-P5R during development. The Pro content measured in different organs suggests that, in addition to transcriptional control of the biosynthetic pathway, the transport of Pro may play a role in its distribution within Arabidopsis. Several aspects of the relationship between Pro metabolism and plant physiology are discussed.
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PMID:Developmental regulation of pyrroline-5-carboxylate reductase gene expression in Arabidopsis. 927 46

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

A cDNA, ERD1, isolated from one-hour-dehydrated plants of Arabidopsis thaliana L. encodes a putative protein that is similar to the regulatory ATPase subunit (ClpA) of the Clp protease and contains a putative chloroplast-targeting transit-peptide at the N-terminus. A chimeric gene with the putative plastid-targeting sequence of the erd1 gene fused to the synthetic green-fluorescent protein (sGFP) gene was constructed and introduced into Arabidopsis protoplasts. The N-terminal region of the ERD1 protein directed the sGFP protein into the plastids of the protoplasts, and functioned as a transit peptide. Northern blot analysis indicated that expression of the erd1 gene was induced not only by water stress, such as dehydration and high salinity, but also by natural senescence and dark-induced etiolation. The erd1 gene was not strongly induced by exogenous abscisic acid. A chimeric gene with the 0.9 kb promoter region of the erd1 gene fused to the beta-glucuronidase (GUS) reporter gene was constructed, and tobacco plants transformed with the construct. The GUS reporter gene driven by the erd1 promoter was induced by dehydration and high salt stress at significant levels in the transgenic plants. The GUS gene was strongly expressed in older leaves without dehydration, and was induced by dark-induced etiolation. Furthermore, GUS activity was reduced by cytokinin treatment during dark-induced etiolation. These results indicate that expression of the erd1 gene is developmentally up-regulated by senescence as well as by water stress.
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PMID:A nuclear gene, erd1, encoding a chloroplast-targeted Clp protease regulatory subunit homolog is not only induced by water stress but also developmentally up-regulated during senescence in Arabidopsis thaliana. 937 97

In order to understand the molecular mechanisms which are responsible for desiccation tolerance in the resurrection plant Craterostigma plantagineum Hochst. a thorough analysis of the CDeT11-24 gene family was performed. CDeT11-24 comprises a small gene family whose genes are expressed in response to dehydration, salt stress and abscisic acid (ABA) treatment in leaves. The gene products are constitutively expressed in roots and disappear only when the plants are transferred to water. It is therefore suggested that the proteins are involved in sensing water status. The predicted proteins are very hydrophilic; they share some features with late-embryogenesis-abundant proteins, and sequence similarities were found with two ABA- and drought-regulated Arabidopsis genes. The analysis of beta-glucuronidase reporter genes driven by the CDeT11-24 promoter showed high activity in mature seeds in both transgenic Arabidopsis and tobacco. In vegetative tissues the promoter activity in response to ABA was restricted to young Arabidosis seedlings. The responsiveness to ABA during later developmental stages was regained in the presence of the Arabidopsis gene product ABI3. Dehydration-induced promoter activity was only observed in Arabidopsis leaves at a particular developmental stage. This analysis indicates that some components in the signal transduction pathway of the resurrection plant are not active in tobacco or Arabidopsis.
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PMID:Gene structure and expression analysis of the drought- and abscisic acid-responsive CDeT11-24 gene family from the resurrection plant Craterostigma plantagineum Hochst. 968 69

We studied the expression of three promoter 5' deletion constructs (-218, -599, and -1312) of the LEA (late embryogenesis abundant)-class gene Dc3 fused to beta-glucuronidase (GUS), where each construct value refers to the number of base pairs upstream of the transcription start site at which the deletion occurred. The Dc3 gene is noted for its induction by abscisic acid (ABA), but its response to other plant hormones and various environmental stresses has not been reported previously for vegetative cells. Fourteen-day-old transgenic tobacco (Nicotiana tabacum L.) seedlings were exposed to dehydration, hypoxia, salinity, exogenous ethylene, or exogenous methyl jasmonate (MeJa). GUS activity was quantified fluorimetrically and expression was observed by histochemical staining of the seedlings. An increase in GUS activity was observed in plants with constructs -599 and -1312 in response to dehydration and salinity within 6 h of stress, and at 12 h in response to hypoxia. No increase in endogenous ABA was found in any of the three lines, even after 72 h of hypoxia. An ABA-independent increase in GUS activity was observed when endogenous ABA biosynthesis was blocked by fluridone and plants were exposed to 5 &mgr;L L-1 ethylene in air or 100 &mgr;M MeJa. Virtually no expression was observed in construct -218 in response to dehydration, salinity, or MeJa, but there was a moderate response to ethylene and hypoxia. This suggests that the region between -218 and -599 is necessary for ABA (dehydration and salinity)- and MeJa-dependent expression, whereas ethylene-mediated expression does not require this region of the promoter.
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PMID:Abscisic acid-dependent and -independent expression of the carrot late-embryogenesis-abundant-class gene Dc3 in transgenic tobacco seedlings 984 92

The cDNA clone ERD5 (early responsive to dehydration), isolated from 1-h-dehydrated Arabidopsis, encodes a precursor of proline (Pro) dehydrogenase (ProDH), which is a mitochondrial enzyme involved in the first step of the conversion of Pro to glutamic acid. The transcript of the erd5 (ProDH) gene was undetectable when plants were dehydrated, but large amounts of transcript accumulated when plants were subsequently rehydrated. Accumulation of the transcript was also observed in plants that had been incubated under hypoosmotic conditions in media that contained L- or D-Pro. We isolated a 1.4-kb DNA fragment of the putative promoter region of the ProDH gene. The beta-glucuronidase (GUS) reporter gene driven by the 1.4-kb ProDH promoter was induced not only by rehydration but also by hypoosmolarity and L- and D-Pro at significant levels in transgenic Arabidopsis plants. The promoter of the ProDH gene directs strong GUS activity in reproductive organs such as pollen and pistils and in the seeds of the transgenic plants. GUS activity was detected in vegetative tissues such as veins of leaves and root tips when the transgenic plants were exposed to hypoosmolarity and Pro solutions. GUS activity increased during germination of the transgenic plants under hypoosmolarity. The relationship between Pro metabolism and the physiological aspects of stress response and development are discussed.
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PMID:A gene encoding proline dehydrogenase is not only induced by proline and hypoosmolarity, but is also developmentally regulated in the reproductive organs of Arabidopsis. 984 97

The expression patterns of senescence-related genes were determined during ozone (O(3)) exposure in Arabidopsis. Rosettes were treated with 0.15 microL L(-1) O(3) for 6 h d(-1) for 14 d. O(3)-treated leaves began to yellow after 10 d of exposure, whereas yellowing was not apparent in control leaves until d 14. Transcript levels for eight of 12 senescence related genes characterized showed induction by O(3). SAG13 (senescence-associated gene), SAG21, ERD1 (early responsive to dehydration), and BCB (blue copper-binding protein) were induced within 2 to 4 d of O(3) treatment; SAG18, SAG20, and ACS6 (ACC synthase) were induced within 4 to 6 d; and CCH (copper chaperone) was induced within 6 to 8 d. In contrast, levels of photosynthetic gene transcripts, rbcS (small subunit of Rubisco) and cab (chlorophyll a/b-binding protein), declined after 6 d. Other markers of natural senescence, SAG12, SAG19, MT1 (metallothionein), and Atgsr2 (glutamine synthetase), did not show enhanced transcript accumulation. When SAG12 promoter-GUS (beta-glucuronidase) and SAG13 promoter-GUS transgenic plants were treated with O(3), GUS activity was induced in SAG13-GUS plants after 2 d but was not detected in SAG12-GUS plants. SAG13 promoter-driven GUS activity was located throughout O(3)-treated leaves, whereas control leaves generally showed activity along the margins. The acceleration of leaf senescence induced by O(3) is a regulated event involving many genes associated with natural senescence.
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PMID:Senescence-associated gene expression during ozone-induced leaf senescence in Arabidopsis. 1044 84

In plants, a cis-acting element, DRE/CRT, is involved in ABA-independent gene expression in response to dehydration and low-temperature stress. To understand signal transduction pathways from perception of the dehydration stress signal to gene expression, we characterized a gene family for DRE/CRT-binding proteins DREB2A and DREB2B in Arabidopsis thaliana. Northern analysis showed that both genes are induced by dehydration and high-salt stress. Organ-specific northern analysis with gene-specific probes showed that these genes are strongly induced in roots by high-salt stress and in stems and roots by dehydration stress. The DREB2A gene is located on chromosome 5, and DREB2B on chromosome 3. We screened an Arabidopsis genomic DNA library with cDNA fragments of DREB2A and DREB2B as probes, and isolated DNA fragments that contained 5'-flanking regions of these genes. Sequence analysis showed that both genes are interrupted by a single intron at identical positions in their leader sequence. Several conserved sequences were found in the promoter regions of both genes. The beta-glucuronidase (GUS) reporter gene driven by the DREB2 promoters was induced by dehydration and high-salt stress in transgenic Arabidopsis plants.
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PMID:Organization and expression of two Arabidopsis DREB2 genes encoding DRE-binding proteins involved in dehydration- and high-salinity-responsive gene expression. 1080 11

Cold stress on plants induces changes in the transcription of cold response genes. A cDNA clone encoding C2H2-type zinc finger protein, SCOF-1, was isolated from soybean. The transcription of SCOF-1 is specifically induced by low temperature and abscisic acid (ABA) but not by dehydration or high salinity. Constitutive overexpression of SCOF-1 induced cold-regulated (COR) gene expression and enhanced cold tolerance of non-acclimated transgenic Arabidopsis and tobacco plants. SCOF-1 localized to the nucleus but did not bind directly to either C-repeat/dehydration (CRT/DRE) or ABA responsive element (ABRE), cis-acting DNA regulatory elements present in COR gene promoters. However, SCOF-1 greatly enhanced the DNA binding activity of SGBF-1, a soybean G-box binding bZIP transcription factor, to ABRE in vitro. SCOF-1 also interacted with SGBF-1 in a yeast two-hybrid system. The SGBF-1 transactivated the beta-glucuronidase reporter gene driven by the ABRE element in Arabidopsis leaf protoplasts. Furthermore, the SCOF-1 enhanced ABRE-dependent gene expression mediated by SGBF-1. These results suggest that SCOF-1 may function as a positive regulator of COR gene expression mediated by ABRE via protein-protein interaction, which in turn enhances cold tolerance of plants.
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PMID:A novel cold-inducible zinc finger protein from soybean, SCOF-1, enhances cold tolerance in transgenic plants. 1120 17


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