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)

Arabidopsis thaliana was transformed with constructs composed of the aquaporin AthH2 promoter and the coding sequence of beta-glucuronidase (GUS) as reporter gene. The transgenic plants obtained were treated with different light qualities or phytohormones and the activity of the AthH2 promoter was determined in situ using a specific GUS assay. With blue light (400-550 nm) and white light, significant activation of the promoter was observed. The same was true for the application of gibberellic acid (GA) and abscisic acid (ABA). In contrast, red light and indole-3-acetic acid (IAA) had only minor effects on the promoter activity. The significance of sequence elements with relation to GA or ABA was confirmed by deletion analyses of the AthH2 promoter. Likewise, a promoter segment with importance for hydathoid specific expression was identified.
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PMID:Regulation of the Arabidopsis thaliana aquaporin gene AthH2 (PIP1b). 903 89

Aquaporins are ubiquitous channel proteins that facilitate the transport of water across cell membranes. Aquaporins show a typically high isoform multiplicity in plants, with 35 homologs in Arabidopsis. The integrated function of plant aquaporins and the function of each individual isoform remain poorly understood. Matrix-assisted laser desorption/ionization time-of-flight analyses suggested that Plasma Membrane Intrinsic Protein2;2 (PIP2;2) is one of the abundantly expressed aquaporin isoforms in Arabidopsis root plasma membranes. Two independent Arabidopsis knockout mutants of PIP2;2 were isolated using a PCR-based strategy from a library of plant lines mutagenized by the insertion of Agrobacterium tumefaciens T-DNA. Expression in transgenic Arabidopsis of a PIP2;2 promoter-beta-glucuronidase gene fusion indicated that PIP2;2 is expressed predominantly in roots, with a strong expression in the cortex, endodermis, and stele. The hydraulic conductivity of root cortex cells, as measured with a cell pressure probe, was reduced by 25 to 30% in the two allelic PIP2;2 mutants compared with the wild type. In addition, free exudation measurements revealed a 14% decrease, with respect to wild-type values, in the osmotic hydraulic conductivity of roots excised from the two PIP2;2 mutants. Together, our data provide evidence for the contribution of a single aquaporin gene to root water uptake and identify PIP2;2 as an aquaporin specialized in osmotic fluid transport. PIP2;2 has a close homolog, PIP2;3, showing 96.8% amino acid identity. The phenotype of PIP2;2 mutants demonstrates that, despite their high homology and isoform multiplicity, plant aquaporins have evolved with nonredundant functions.
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PMID:Role of a single aquaporin isoform in root water uptake. 1256 88

We investigated the fourth subgroup of Arabidopsis aquaporin, small and basic intrinsic proteins (SIPs). When they were expressed in yeast, SIP1;1 and SIP1;2, but not SIP2;1, gave water-channel activity. The transient expression of SIPs linked with green fluorescent protein in Arabidopsis cells and the subcellular fractionation of the tissue homogenate showed their ER localization. The SIP proteins were detected in all of the tissues, except for dry seeds. Histochemical analysis of promoter-beta-glucuronidase fusions revealed the cell-specific expression of SIPs. SIP1;1 and SIP1;2 may function as water channels in the ER, while SIP2;1 might act as an ER channel for other small molecules or ions.
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PMID:Novel type aquaporin SIPs are mainly localized to the ER membrane and show cell-specific expression in Arabidopsis thaliana. 1622 86

Calcium is an essential macronutrient for plants and functions in signal transduction. Regulation of the cytosolic calcium concentration is required for normal cell growth. In calcium homeostasis in plant cells, Ca(2+)/H(+) exchangers are involved in Ca(2+) compartmentalization into intracellular compartments. Here, we examine the intracellular localization of a rice Ca(2+)/H(+) exchanger, OsCAX1a, fused to a green fluorescent protein and transiently expressed in onion epidermis and rice protoplasts. Green fluorescence was observed in the vacuolar membrane. After sucrose gradient centrifugation of the homogenate of rice plants, OsCAX1a was detected in the same fraction as the vacuolar membrane aquaporin gamma-TIP. We then quantified the mRNA and protein of OsCAX1a in plants grown with metal ions. OsCAX1a mRNA was induced in roots by high concentrations of Ca(2+). The protein level in shoots was also increased in the presence of high concentrations of Ca(2+). Furthermore, transgenic rice plants transformed with the OsCAX1a promoter fused to beta-glucuronidase showed reporter expression in vascular bundles, stomata, trichomes, steles, flowers, embryos and aleurone layers. In the case of stomata and trichomes, transcription of OsCAX1a was particularly high in aged organs. These results suggest that OsCAX1a transports Ca(2+) into vacuoles and is involved in Ca(2+) homeostasis in cells that suffer from high concentrations of Ca(2+).
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PMID:Expression of the vacuolar Ca2+/H+ exchanger, OsCAX1a, in rice: cell and age specificity of expression, and enhancement by Ca2+. 1627 57

Arsenite [As(III)] is highly toxic to organisms, including plants. Very recently, transporters in rice responsible for As(III) transport have been described (Ma, J. F., Yamaji, N., Mitani, N., Xu, X. Y., Su, Y. H., McGrath, S. P., and Zhao, F. J. (2008) Proc. Natl. Acad. Sci. U. S. A. 105, 9931-9935), but little is known about As(III) tolerance. In this study, three independent As(III)-tolerant mutants were isolated from ethyl methanesulfonate-mutagenized M2 seeds of Arabidopsis thaliana. All three mutants carried independent mutations in Nodulin 26-like intrinsic protein 1;1 (NIP1;1), a homolog of an aquaporin. Two independent transgenic lines carrying T-DNA in NIP1;1 were highly tolerant to As(III), establishing that NIP1;1 is the causal gene of As(III) tolerance. Because an aquaglyceroporin is able to transport As(III), we measured As(III) transport activity. When expressed in Xenopus oocytes, NIP1;1 was capable of transporting As(III). As content in the mutant plants was 30% lower than in wild-type plants. Promoter beta-glucuronidase and real-time PCR analysis showed that NIP1;1 is highly expressed in roots, and GFP-NIP1;1 is localized to the plasma membrane. These data show that NIP1;1 is involved in As(III) uptake into roots and that disruption of NIP1;1 function confers As(III) tolerance to plants. NIP1;2 and NIP5;1, closely related homologs of NIP1;1, were also permeable to As(III). Although the disruption of these genes reduced the As content in plants, As(III) tolerance was not observed in nip1;2 and nip5;1 mutants. This indicates that As(III) tolerance cannot be simply explained by decreased As contents in plants.
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PMID:NIP1;1, an aquaporin homolog, determines the arsenite sensitivity of Arabidopsis thaliana. 1902 97

Under nitrogen-limiting conditions, legumes interact with symbiotic rhizobia to produce nitrogen-fixing root nodules. We have previously shown that glutathione and homoglutathione [(h)GSH] deficiencies impaired Medicago truncatula symbiosis efficiency, showing the importance of the low M(r) thiols during the nodulation process in the model legume M. truncatula. In this study, the plant transcriptomic response to Sinorhizobium meliloti infection under (h)GSH depletion was investigated using cDNA-amplified fragment length polymorphism analysis. Among 6,149 expression tags monitored, 181 genes displayed significant differential expression between inoculated control and inoculated (h)GSH depleted roots. Quantitative reverse transcription polymerase chain reaction analysis confirmed the changes in mRNA levels. This transcriptomic analysis shows a down-regulation of genes involved in meristem formation and a modulation of the expression of stress-related genes in (h)GSH-depleted plants. Promoter-beta-glucuronidase histochemical analysis showed that the putative MtPIP2 aquaporin might be up-regulated during nodule meristem formation and that this up-regulation is inhibited under (h)GSH depletion. (h)GSH depletion enhances the expression of salicylic acid (SA)-regulated genes after S. meliloti infection and the expression of SA-regulated genes after exogenous SA treatment. Modification of water transport and SA signaling pathway observed under (h)GSH deficiency contribute to explain how (h)GSH depletion alters the proper development of the symbiotic interaction.
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PMID:(Homo)glutathione depletion modulates host gene expression during the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti. 1958 96

Victims of nuclear accidents or radiological terrorism are likely to receive varying doses of ionizing radiation inhomogeneously distributed over the body. Early biomarkers may be useful in determining organ-specific doses due to total body irradiation (TBI) or partial body irradiation. The authors used liquid chromatography and mass spectrometry to compare the effect of TBI and local kidney irradiation (LKI) on the rat urine proteome using a single 10-Gy dose of x-rays. Both TBI and LKI altered the urinary protein profile within 24 h with noticeable differences in gene ontology categories. Some proteins, including fetuin-B, tissue kallikrein, beta-glucuronidase, vitamin D-dependent calcium binding protein and chondroitin sulfate proteoglycan NG2, were detected only in the TBI group. Some other proteins, including major urinary protein-1, RNA binding protein 19, neuron navigator, Dapper homolog 3, WD repeat and FYVE domain containing protein 3, sorting nexin-8, ankycorbin and aquaporin were detected only in the LKI group. Protease inhibitors and kidney proteins were more abundant (fraction of total scans) in the LKI group. Urine protein (Up) and creatinine (Uc) (Up/Uc) ratios and urinary albumin abundance decreased in both TBI and LKI groups. Several markers of acute kidney injury were not detectable in either irradiated group. Present data indicate that abundance and number of proteins may follow opposite trends. These novel findings demonstrate intriguing differences between TBI and LKI, and suggest that urine proteome may be useful in determining organ-specific changes caused by partial body irradiation.
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PMID:The urine proteome for radiation biodosimetry: effect of total body vs. local kidney irradiation. 2006 82