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)

Nicotine alkaloids are synthesized in the root of Nicotiana species, and their synthesis increases after insect attack, wounding and jasmonate treatment of the leaf. Putrescine N-methyltransferase (PMT) catalyzes the first committed step in nicotine biosynthesis. The expression patterns of the three Nicotiana sylvestris PMT genes (NsPMT1, NsPMT2, and NsPMT3) are reported in this study. Transcripts of the NsPMT genes were detected only in the root, and were up-regulated by methyl jasmonate treatment. When the 5'-flanking regions of NsPMT1, NsPMT2, and NsPMT3 were fused independently to beta-glucuronidase reporter gene and introduced into N. sylvestris by Agrobacterium-mediated transformation, all introduced transgenes were expressed in the cortex, endodermis, and xylem in the root, as well as upregulated by methyl jasmonate treatment. These qualitatively similar patterns of expression for the NsPMT genes are achieved with only 0.25 kb of their conserved 5'-flanking regions, which contained no known jasmonate-responsive elements.
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PMID:Jasmonate induction of putrescine N-methyltransferase genes in the root of Nicotiana sylvestris. 1096 39

Putrescine N-methyltransferase (PMT) catalyzes the first committed step in the biosynthesis of pyrrolinium ring-containing alkaloids. Earlier studies have indicated that PMT gene expression is restricted to root tissue in Solanaceus plant species. During the analysis to further elucidate factors that govern the regulation of alkaloid synthesis, evidence was found for a novel expression pattern dictated by the 5'-flanking region of at least two members of the PMT-gene family. A 627-bp DNA fragment upstream of the NtPMT3 gene was fused to the beta-glucuronidase (GUS) reporter gene and used to produce stable transgenic lines of Nicotiana tabacum. Fluorometric and histochemical assays conducted on transgenic plants indicated high expression levels in root tissue and, in agreement with previous studies, no expression was detected in leaves. However, expression was observed in leaves when they were mechanically wounded. This expression was highly localized around the wound site and showed little evidence of long distance signaling, including lack of responsiveness to jasmonic acid. Expression was transient, with maximum levels immediately after wounding and diminishing after approximately 2-4 h. RT-PCR analysis of mRNA isolated from wild-type plants also indicated upregulation of PMT expression in leaves upon wounding as well as very low transcript levels in unwounded leaves. Low levels of PMT activity were detected in leaf tissue, which did not increase significantly upon wounding.
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PMID:Wound-induced gene expression of putrescine N-methyltransferase in leaves of Nicotiana tabacum. 1245 72

Putrescine N-methyltransferase (PMT) catalyzes the first committed step of nicotine biosynthesis, converting putrescine into N-methylputrescine. A variety of chemical, environmental, and developmental cues have been implicated in its regulation. Here we have examined the differential expression of beta-glucuronidase (GUS) transgenes under the control of the transcriptional regulatory sequences of four distinct members of the NtPMT gene family from tobacco (Nicotiana tabacum L.). BY-2 cell cultures expressing various NtPMT promoter-GUS constructs were examined for their response to treatment with various combinations of methyl jasmonate (MeJA), auxin (AUX), and ethylene (ETH). All four NtPMT gene promoters examined were inducible by MeJA, although the extent of the induction varied dramatically, with the NtPMT1a promoter being the most responsive. High AUX levels in the cell growth media repressed NtPMT::GUS transgene expression and inhibited their MeJA-induced transcription. Treatment of BY-2 cells with ETH alone did not result in a significant alteration in NtPMT::GUS expression. However, similar to AUX, ETH treatment led to the suppression of MeJA-induced transcription. Detailed deletion analysis of the NtPMT1a gene promoter showed that as little as 111 bp upstream of the transcriptional start site were sufficient to confer MeJA-responsiveness. Deletion of a conserved G-box element (GCACGTTG) at -103 to -96 bp completely abolished MeJA-responsiveness. Further mutagenesis studies revealed that in addition to a functional G-box, MeJA-responsiveness of the NtPMT1a promoter also required a TA-rich region and a GCC-motif (TGCGCCC) located at -80 to -69 bp and -62 to -56 bp relative to the start site, respectively. A synthetic G-box tetramer (4 X syn G-box) fused to a -83 bp fragment from the NtPMT1a promoter (containing the TA-rich region, GCC-box, and TATA-box) displayed a 30-fold induction by MeJA treatment, whereas when the 4 X syn G-box was fused to a minimal (-46 bp) promoter fragment derived from the CaMV 35S gene, no induction by MeJA treatment was detected. Our results indicate that multiple intersecting signal transduction pathways and different transcriptional regulatory factors are involved in mediating JA-responsiveness of NtPMT expression in tobacco.
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PMID:Methyl jasmonate induced expression of the tobacco putrescine N -methyltransferase genes requires both G-box and GCC-motif elements. 1560 14

While polyamines (PAs) have been suggested to protect cells against Reactive Oxygen Species (ROS), their catabolism is known to generate ROS. We compared the activities of several enzymes and cellular metabolites involved in the ROS scavenging pathways in two isogenic cell lines of poplar (Populus nigraxmaximowiczii) differing in their PA contents. Whereas the control cell line was transformed with beta-glucuronidase (GUS), the other, called HP (High Putrescine), was transformed with a mouse ornithine decarboxylase (mODC) gene. The expression of mODC resulted in several-fold increased production of putrescine as well its enhanced catabolism. The two cell lines followed a similar trend of growth over the seven-day culture cycle, but the HP cells had elevated levels of soluble proteins. Accumulation of H(2)O(2) was higher in the HP cells than the control cells, and so were the activities of glutathione reductase and monodehydroascorbate reductase; the activity of ascorbate peroxidase was lower in the former. The contents of reduced glutathione and glutamate were significantly lower in the HP cells but proline was higher on some days of analysis. There was a small difference in mitochondrial activity between the two cell lines, and the HP cells showed increased membrane damage. In the HP cells, increased accumulation of Ca was concomitant with lower accumulation of K. We conclude that, while increased putrescine accumulation may have a protective role against ROS in plants, enhanced turnover of putrescine actually can make them vulnerable to increased oxidative damage.
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PMID:Putrescine overproduction negatively impacts the oxidative state of poplar cells in culture. 1913 66