Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gal4p activates transcription of the Saccharomyces GAL genes in response to galactose and is phosphorylated during interaction with the RNA polymerase II (Pol II) holoenzyme. One phosphorylation at S699 is necessary for full GAL induction and is mediated by Srb10p/CDK8 of the RNA Pol II holoenzyme mediator subcomplex. Gal4p S699 phosphorylation is necessary for sensitive response to inducer, and its requirement for GAL induction can be abrogated by high concentrations of galactose in strains expressing wild-type GAL2 and GAL3. Gal4p S699 phosphorylation occurs independently of Gal3p and is responsible for the long-term adaptation response observed in gal3 yeast. SRB10 and GAL3 are shown to represent parallel mechanisms for GAL gene induction. These results demonstrate that Gal4p activity is controlled by two independent signals: one that acts through Gal3p-galactose and a second that is mediated by the holoenzyme-associated cyclin-dependent kinase Srb10p. Since Srb10p is regulated independently of galactose, our results suggest a function for CDK8 in coordinating responses to specific inducers with the environment through the phosphorylation of gene-specific activators.
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PMID:Multiple signals regulate GAL transcription in yeast. 1080 31

We cloned four genes from the Porphyromonas gingivalis chromosome, the gene products of which catalyze the anabolism of dTDP-L-rhamnose from D-glucose-1-phosphate when they were expressed in Escherichia coli. The amino acid sequences deduced from these genes showed significant homology to proteins encoded by the rml genes involved in dTDP-L-rhamnose biosynthesis in other gram-negative bacteria. Reverse transcriptase polymerase chain reaction analysis revealed that these four genes are expressed as a single transcript in P. gingivalis. To clarify the role of the rml gene homologs in this organism, construction of mutants defective in the rml gene homologs was attempted by allelic exchange. Unexpectedly, any mutants defective in the rml gene homologs were unable to be isolated, and the allelic exchange was possible only if the wild-type rml gene homologs were present on the chromosome. These results suggest that the rml gene homologs might be essential for the viability of P. gingivalis under the culture conditions used in this study.
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PMID:Isolation and characterization of the rml gene homologs from Porphyromonas gingivalis. 1089 88

We have previously reported that YaaH and YrbA are spore proteins of Bacillus subtilis that are required for spore resistance and/or germination and that they have a motif conserved among so-called cell wall binding proteins [Kodama et al. (1999) J. Bacteriol. 181, 4584-4591, Takamatsu et al. (1999) J. Bacteriol. 181, 4986-4994]. In this study, we analyzed the expression of ydhD, ykuD, and ykvP genes, which encode putative proteins containing the same motif. Transcription of ydhD was dependent on SigE, and the mRNA was detectable from 2 h after the cessation of logarithmic growth (T(2) of sporulation). ykuD was transcribed by SigK RNA polymerase from T(4) of sporulation. Both SigK and GerE were essential for ykvP expression, and this gene was transcribed from T(5) of sporulation. Inactivation of these genes by insertion of an erythromycin resistance gene did not affect vegetative growth, spore resistance to heat, chloroform, and lysozyme, or spore germination in the presence of L-alanine or in a mixture of L-asparagine, D-glucose, D-fructose, and potassium chloride. The His tag fusions of YdhD, YkuD, and YkvP downstream of their natural promoter regions were introduced into a multicopy plasmid. These fusion proteins were produced during sporulation in B. subtilis transformants and were detected in mature spores, indicating that YdhD, YkuD, and YkvP are all proteins intrinsic to spores. Excessive YkuD and YkvP in the sporulating cells did not affect spore resistance or germination. The cells producing excessive YdhD also did not show impaired spore resistance, but their germination properties were changed: the spores revealed reduced response to L-alanine and some of them germinated even without germinants. Escherichia coli b-lactamase, whose signal sequence had been genetically replaced by the cell wall binding motif of YaaH, was produced in sporulating cells, and Western blot analysis indicated that the fused protein was assembled into spores. We speculate that the conserved motif functions as a kind of signal sequence involved in assembly of these proteins on forespores.
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PMID:Synthesis and characterization of the spore proteins of Bacillus subtilis YdhD, YkuD, and YkvP, which carry a motif conserved among cell wall binding proteins. 1101 Nov 48

Aucubin, an iridoid glucoside, was investigated to determine whether it has a stimulating effect on alpha-amanitin excretion in alpha-amanitin intoxicated rats, and whether there is binding activity to calf thymus DNA. High-performance liquid chromatography (HPLC) analysis of alpha-amanitin in rat urine allowed quantitative measurement of the alpha-amanitin concentration with a detection limit of 50 ng/ml. In this system, a group treated with both alpha-amanitin and aucubin showed that alpha-amanitin was excreted about 1.4 times faster than in the alpha-amanitin only treated group. Our previous results showed that the toxicity of alpha-amanitin is due to specific inhibition of RNA polymerase activity and the resultant blockage of the synthesis of certain RNA species in the nucleus. However, no significant activity change on RNA polymerase from Hep G2 cells was observed when aucubin was treated with alpha-amanitin at any concentration tested. Nevertheless, aucubigenin inhibited both DNA polymerase (IC50, 80.5 microg/ml) and RNA polymerase (IC50, 135.0 microg/ml) from the Hep G2 cells. The potential of both alpha-amanitin and aucubin to interact with DNA were examined by spectrophotometric analysis. Alpha-Amanitin showed no significant binding capacity to calf thymus DNA, but aucubin was found to interact with DNA, and the apparent binding constant (Kapp) and apparent number of binding sites per DNA phosphate (Bapp) were 0.45 x 10(4) M(-1) and 1.25, respectively.
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PMID:Studies on the possible mechanisms of protective activity against alpha-amanitin poisoning by aucubin. 1123 13

RNA polymerase is known to bind and utilize the overlapping promoters P1 and P2 in Escherichia coli galactose operon. We have identified an additional specific site upstream of P2, where RNA polymerase binds in a heparin-resistant manner. Binding of polymerase to this site, termed P3, occurs simultaneous to its binding at P1/P2. We have located this P3 site by DNase I footprinting. A 63 base pair region centered around position - 100 with respect to galP1 is protected by polymerase. Interestingly, a Pribnow box TATAAT is present within this protected region (-103 to -108). We have shown that transcription occurs from P3 in vitro. Primer extension analysis provides direct evidence that P3 is transcribed in vivo. The start site of transcription has been mapped at -96 position relative to galP1. beta-galactosidase assays with different gal promoter constructs reveal that while P3 alone functions as a weak in vivo promoter, it has a synergistic effect on transcription from the gal operon, since deletion of P3 or specifically mutating its -10 region result in a substantial reduction in the gal promoter activity.
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PMID:A novel RNA polymerase binding site upstream of the galactose promoter in Escherichia coli exhibits promoter-like activity. 1129 53

The BglG protein is a transcriptional antiterminator acting within the beta-glucoside operon of Escherichia coli by binding to a specific sequence motif in the growing mRNA. Binding of BglG prevents formation of the terminator stem-loop structure, thereby causing the RNA polymerase to continue transcription. Activity of BglG is modulated in a complex way by antagonistically acting phosphorylations in response to the availability of beta-glucosidic substrates and to the catabolic state of the cell. The enzymes responsible for these phosphorylations are members of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) that represents a central carbohydrate uptake and signal transduction system. As these enzymes are believed to all form higher-order complexes associated with the cytoplasmic membrane, we tested whether or not BglG would remain active when artificially anchored to its presumptive site of regulation, the inner membrane. We show that the membrane-anchored protein indeed efficiently catalyzes transcriptional antitermination. Moreover, the membrane-attached BglG remains regulated by the PTS. Thus, a membrane-bound regulatory RNA binding protein can potentially interact fast enough with its target within the nascent transcript and cause the transcriptional machinery to proceed, before transcriptional termination would occur. Consequently, there is no principal necessity for an RNA-binding transcriptional regulator like BglG to leave the inner membrane, a potential regulatory site, and migrate to the site of transcription, the nucleoid.
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PMID:Efficient transcriptional antitermination from the Escherichia coli cytoplasmic membrane. 1132 58

To investigate the cellular functions of sulfated glycosphingolipids, we introduced the cerebroside sulfotransferase (CST) gene into J5 cells, a subclone of 3LL Lewis lung carcinoma cells. The J5 cells lack acidic glycosphingolipids but accumulate their common biosynthetic precursor, lactosylceramide. We established the stable CST transfectants, J5/CST-1 and J5/CST-2 clones, highly expressing sulfated lactosylceramide (SM3). Both clones exhibited more spherical morphology in comparison to mock transfectant, and their adhesiveness to fibronectin and laminin was significantly lower. The loss of cell-substratum interactions in these SM3-expressing cells could be attributed to decreased expression of integrins (alpha(5), alpha(6), and beta(1)) on the cell surface and their whole cellular levels. However, the levels of H-2K(b) and H-2D(b) antigens remained unchanged. Reverse transcriptase-polymerase chain reaction and Northern blot analyses for these integrins exhibited significant decrease of beta(1) gene expression in J5/CST-1 and 2, but there was no change in the levels of alpha(5) and alpha(6) transcripts. Deglycosylation by endoglycosidase H treatment clearly demonstrated that the precursor form of beta(1) integrin, possessing high mannose oligosaccharide chains, was preferentially decreased in the CST transfectants. These results demonstrate that endogenous SM3 negatively regulates beta(1) integrin expression at the transcriptional level, and the decrease of alpha integrin proteins in the CST transfectants was due to the post-transcriptional modification. We suggest the putative importance of the intracellular pre-beta(1) integrin pool for normal integrin maturation and subsequent function. Although the rates of cell proliferation in vitro for mock and CST transfectants were similar, tumorigenicity of J5/CST-1 and -2 cells inoculated into syngeneic C57/BL6 mice was greatly decreased or even absent. This was probably due to global loss of the efficient cell-matrix interactions, which are essential for the development of malignant tumors in vivo. Thus, we showed the evidence that cellular SM3 negatively regulates the cell-substratum interaction, resulting in the loss of tumorigenicity.
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PMID:Suppression of integrin expression and tumorigenicity by sulfation of lactosylceramide in 3LL Lewis lung carcinoma cells. 1135 5

Sensitivity of Listeria monocytogenes to the bacteriocin mesentericin Y105 was previously shown to be dependent on the sigma(54) subunit of the RNA polymerase. This points towards expression of particular sigma(54)-dependent genes. The present study describes first, ManR, a new sigma(54)-associated activator, and second, Ell(t)(Man), a new sigma(54)-dependent PTS permease of the mannose family, both involved in sensitivity to mesentericin Y105, since interruption of their corresponding genes led to resistance of L. monocytogenes EGDe. Ell(t)(Man) is likely composed of three subunits encoded by the mpt operon (mptA, mptC and mptD genes). Interruption of either the proximal (mptA) or distal (mptD) gene led to resistance, supporting results obtained in Enterococcus faecalis. Accordingly, such PTS permeases of the mannose family should be involved in sensitivity of different target strains to mesentericin Y105. In L. monocytogenes, expression of the mpt operon is shown to be controlled by sigma(54) and ManR and to be induced by both glucose and mannose. The latter result indicates that these sugars are transported by the Ell(t)(Man) permease. Moreover, these sugars correlatively induce sensitivity of L. monocytogenes to mesentericin Y105, strongly favouring the primary role of Ell(t)(Man). MptD, a membrane subunit of Ell(t)(Man), presents an additional domain compared to most IID(Man) subunits described in data banks. An in-frame deletion of this domain in mptD led to resistance of L. monocytogenes, showing its connection with sensitivity and suggesting that it could be directly involved in the recognition of the target cell by mesentericin Y105. Taken together, the results of this work demonstrate that Ell(t)(Man) is prominent in sensitivity to mesentericin Y105 and could be a receptor for subclass IIa bacteriocins.
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PMID:A sigma(54)-dependent PTS permease of the mannose family is responsible for sensitivity of Listeria monocytogenes to mesentericin Y105. 1173 58

To understand primary cell wall assembly in Arabidopsis, we have focused on identifying and characterizing enzymes involved in xyloglucan biosynthesis. Nine genes (AtFUT2-10) were identified that share between 47% and 62% amino acid similarity with the xyloglucan-specific fucosyltransferase AtFUT1. Reverse transcriptase-PCR analysis indicates that all these genes are expressed. Bioinformatic analysis predicts that these family members are fucosyltransferases, and we first hypothesized that some may also be involved in xyloglucan biosynthesis. AtFUT3, AtFUT4, and AtFUT5 were expressed in tobacco (Nicotiana tabacum L. cv BY2) suspension culture cells, and the resulting proteins did not transfer fucose (Fuc) from GDP-Fuc to tamarind xyloglucan. AtFUT3, AtFUT4, and AtFUT5 were overexpressed in Arabidopsis plants. Leaves of plants overexpressing AtFUT4 or AtFUT5 contained more Fuc than wild-type plants. Stems of plants overexpressing AtFUT4 or AtFUT5 contained more xylose, less arabinose, and less galactose than wild-type plants. We suggest that the AtFUT family is likely to include fucosyltransferases important for the synthesis of wall carbohydrates. A targeted analysis of isolated cell wall matrix components from plants altered in expression of these proteins will help determine their specificity and biological function.
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PMID:Characterization of a family of Arabidopsis genes related to xyloglucan fucosyltransferase1. 1174 4

This study demonstrated that a galactose-binding protein (GBP) produced by a fish pathogenic water mold, Aphanomyces piscicida, activates carp leukocytes. Leukocytes were separated from the head kidney and peripheral blood using Percoll density centrifugation. A flow cytometric analysis revealed that GBP binds with many cells and a variety of cell types including lymphocytes, granulocytes and thrombocytes. Intracellular calcium flux of the peripheral blood leukocytes induced by stimulation with GBP was confirmed by counting the fluo-3 loaded cells whose fluorescence increased after the stimulation using flow cytometry. The percentage of cells in which a calcium flux was induced peaked 1 min after the stimulation. Approximately 6% of the cells specifically responded 1 min after the stimulation. The proliferation response was determined by the level of BrdU uptake by the leukocytes after the stimulation. Cell proliferation was observed 2, 4 and 6 days after stimulation with GBP. The expression of cytokines IL-1beta and TGF-beta1 in the peripheral blood leukocytes, after the stimulation was evaluated by a semi-quantitative reverse-transcriptase polymerase chain reaction. Increased expression of IL-1beta was observed 4h after stimulation with GBP. Variation of TGF-beta1 expression under the same conditions was not observed. The kinetics of intracellular calcium flux and the level of IL-1beta expression induced by GBP stimulation were different from those induced by phytohemagglutinin stimulation. These results confirmed that GBP is a pathogenic microbial component that can induce cell activation. GBP seems to induce the inflammatory response observed in the Aphanomyces infection.
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PMID:Activation of carp leukocytes by a galactose-binding protein from Aphanomyces piscicida. 1190 25


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