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)

A full-length cDNA clone encoding cytosolic glutamine synthetase (GS), expressed in roots and root nodules of soybean, was isolated by direct complementation of an Escherichia coli gln A- mutant. This sequence is induced in roots by the availability of ammonia. A 3.5-kilobase promoter fragment of a genomic clone (lambda GS15) corresponding to this cDNA was isolated and fused with a reporter [beta-glucuronidase (GUS)] gene. The GS-GUS fusion was introduced into a legume (Lotus corniculatus) and a nonlegume (tobacco) plant by way of Agrobacterium-mediated transformations. This chimeric gene was found to be expressed in a root-specific manner in both tobacco and L. corniculatus, the expression being restricted to the growing root apices and the vascular bundles of the mature root. Treatment with ammonia increased the expression of this chimeric gene in the legume background (i.e., L. corniculatus); however, no induction was observed in tobacco roots. Histochemical localization of GUS activity in ammonia-treated transgenic L. corniculatus roots showed a uniform distribution across all cell types. These data suggest that the tissue specificity of the soybean cytosolic GS gene is conserved in both tobacco and L. corniculatus; however, in the latter case, this gene is ammonia inducible. Furthermore, the ammonia-enhanced GS gene expression in L. corniculatus is due to an increase in transcription. That this gene is directly regulated by externally supplied or symbiotically fixed nitrogen is also evident from the expression of GS-GUS in the infection zone, including the uninfected cells, and the inner cortex of transgenic L. corniculatus nodules, where a flux of ammonia is encountered by this tissue. The lack of expression of GS-GUS in the outer cortex of the nodules suggests that ammonia may not be able to diffuse outside the endodermis.
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PMID:Ammonia-regulated expression of a soybean gene encoding cytosolic glutamine synthetase in transgenic Lotus corniculatus. 168 99

A DNA fragment containing sequences hybridizing to the 5' region of GS15, a gene encoding soybean cytosolic glutamine synthetase, was isolated from a soybean genomic library. Mapping and partial sequence analysis of the genomic clone revealed that it encodes a cytosolic GS gene, GS21, which is different from GS15. In parallel, a number of cDNA clones encoding cytosolic GS were isolated using the coding region of pGS20 as a probe (pGS20 is a cDNA clone which corresponds to a transcript of the GS15 gene). Two new full-length cDNAs designated pGS34 and pGS38 were isolated and sequenced. In the 5' non-coding region a strong homology was found between the two clones and the GS21 gene. However, none of these sequences were identical, which suggests that there are at least three members in this group of genes. In order to determine their relative levels of transcription, specific sequences from pGS34, pGS38 and GS21 were used in an RNAse protection assay. This experiment clearly showed that GS21 and the gene encoding pGS38 are specifically expressed in young or mature nodules, whereas the gene encoding pGS34 is highly transcribed in nodules and constitutively expressed at a lower level in other soybean organs. In order to further analyse the molecular mechanisms controlling GS21 transcription, different fragments of the promoter region were fused to the Escherichia coli reporter gene encoding beta-glucuronidase (GUS) and the constructs were introduced into Lotus corniculatus via Agrobacterium rhizogenes-mediated transformation. Analysis of GUS activity showed that the GS21 promoter-GUS constructs were expressed in the vasculature of all vegetative organs. This result is discussed in relation to species-specific metabolic and developmental characteristics of soybean and Lotus.
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PMID:Identification of several soybean cytosolic glutamine synthetase transcripts highly or specifically expressed in nodules: expression studies using one of the corresponding genes in transgenic Lotus corniculatus. 786 79