Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A cDNA which encodes the entire amino acid (aa) sequence of the mature jack bean urease has been cloned in Escherichia coli from a library prepared from the mRNA of developing jack beans. It was necessary to use reverse transcriptase in the cDNA was obtained in the form of two contiguous DNA fragments, each of which was completely sequenced. The conceptual translation of the nt sequence gave an 840-aa sequence which was identical to the directly determined sequence except for one conservative aa substitution (Takashima et al., Eur. J. Biochem. 175 (1988) 151-165). These data constitute the first report on the cloning and sequence of the cDNA encoding a urease from any higher plant.
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PMID:Cloning and sequencing of a jack bean urease-encoding cDNA. 144 38

Helicobacter pylori urease is absorbed into the gastric mucosa at sites of inflammation, but whether the enzyme activates mucosal macrophages is not known. Because mucosal macrophages differ phenotypically and functionally from blood monocytes, whether recombinant H. pylori urease (rUrease) activated purified lamina propria macrophages in vitro was investigated. rUrease (1-10 microgram/mL) induced primary mucosal macrophages to produce interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha but not IL-8 proteins in a dose-dependent manner (P<.05 to P<.001). Quantitative reverse transcriptase-polymerase chain reaction using capillary electrophoresis laser-induced fluorescence showed that rUrease (0.1-10 microgram/mL) also induced dose-dependent expression of IL-1beta, IL-6, and TNF-alpha but not IL-8 mRNA (P<.05), suggesting that rUrease-induced production of certain cytokines is regulated at the level of gene transcription. These findings indicate that the ability of H. pylori urease to activate mucosal macrophages, resulting in production of proinflammatory cytokines, may be involved in the pathogenesis of H. pylori-associated mucosal inflammation.
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PMID:Recombinant Helicobacter pylori urease activates primary mucosal macrophages. 978 Feb 78

Helicobacter pylori (Hp) is a major risk factor of peptic ulcer but studies on the relation between Hp infection and gastric pathology are limited due to lack of convenient models resembling Hp infection in humans. We studied the effects of inoculation of conventional BALB/c mice with toxigenic type I Hp (cagA+ and vacA+) and non-toxigenic type II Hp (cagA- and vacA-) vs administration of vehicle on gastric secretion and healing of gastric ulcers. The gastric secretion studies were performed on mice with chronic gastric fistula before and after inoculation with toxigenic or non-toxigenic Hp strain or administration of vehicle (saline). Gastric ulcers were produced in mice inoculated with toxigenic and non-toxigenic Hp strain or vehicle and then sacrificed at day 0 and after 2, 4, 7, 14 and 28 days. Ulcer area and gastric blood flow (GBF), plasma gastrin and gastric luminal somatostatin were determined. Gastric mucosal biopsy specimens were also taken for the assessment of the presence of viable Hp using rapid urease test, the Hp-culture and the reverse transcriptase--polymerase chain reaction (RT-PCR) analysis of the signal for Hp CagA. Gastric acid output was reduced by over 50% immediately after Hp inoculation and this effect persisted during all time intervals tested, being significantly more pronounced in type I Hp-infected stomach. The area (7 mm2) of ulcers in control mice decreased gradually and then continued to decline during 14 days to disappear almost completely after 28 days. In contrast, the ulcers were present till day 28 in all mice infected with type I or type II Hp strain being significantly larger especially with type I Hp-infection. The GBF in control mice showed gradual rise with decreasing ulcer size being significantly higher at the ulcer margin than the ulcer crater and reached after 14 and 28 days the value not significantly different from that in vehicle-administered mice. In contrast, the GBF in type I Hp-infected mice but to a lesser extent, in type II Hp infected mice was significantly lower than in the vehicle controls, both at the ulcer margin and the crater of ulcers at all tested days. Hp-infection was accompanied by significant increment in plasma gastrin and the fall in gastric somatostatin contents observed at all test days, particularly in mice infected with type I Hp strain. Edema of surface epithelium appeared after 7 days and wak but significant mucosal inflammatory infiltration occurred after 14 days to further increase after 28 days, especially in type I Hp and less in type II Hp infected mice. We conclude that conventional mice with gastric ulcers can be successfully infected by both toxigenic and non-toxigenic Hp strains and this infection markedly reduces gastric acid secretion and delays healing of ulcers probably due to the fall in mucosal microcirculation in ulcer area, mucosal inflammation and impairment in gastric-somatostatin link.
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PMID:Gastric secretion and ulcer healing in mouse stomach infected with cytotoxin expressing strain of Helicobacter pylori. 978 92

Despite increasing knowledge on the biology of Helicobacter pylori, little is known about the expression pattern of its genome during infection. While mouse models of infection have been widely used for the screening of protective antigens, the reliability of the mouse model for gene expression analysis has not been assessed. In an attempt to address this question, we have developed a quantitative reverse transcriptase PCR (RT-PCR) that allowed the detection of minute amounts of mRNA within the gastric mucosa. The expression of four genes, 16S rRNA, ureA (encoding urease A subunit), katA (catalase), and alpA (an adhesin), was monitored during the course of a 6-month infection of mice and in biopsy samples from of 15 infected humans. We found that the selected genes were all expressed within both mouse and human infected mucosae. Moreover, the relative abundance of transcripts was the same (16S rRNA > ureA > katA > alpA), in the two models. Finally, results obtained with the mouse model suggest a negative effect of bacterial burden on the number of transcripts of each gene expressed per CFU (P < 0.05 for 16S rRNA, alpA, and katA). Overall, this study demonstrates that real-time RT-PCR is a powerful tool for the detection and quantification of H. pylori gene expression within the gastric mucosa and strongly indicates that mice experimentally infected with H. pylori provide a valuable model for the analysis of bacterial gene expression during infection.
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PMID:Assessment of Helicobacter pylori gene expression within mouse and human gastric mucosae by real-time reverse transcriptase PCR. 1144 48

The expression of the virulence-associated genes ureA, encoding the urease subunit A, and nap, encoding the neutrophil activating protein, in Helicobacter pylori grown both in the stomach of C57/Bl6 mice and in Brucella broth was quantified by quantitative competitive reverse transcriptase-PCR using a homologous RNA standard (competitor) and an external standard (16S rRNA). The results showed that the ureA and nap transcripts were increased up to 15 and 80 times, respectively, in vivo compared to in vitro. The transcription of ureA and nap also differed in that ureA showed highest expression early in infection in mice whereas nap transcription was variable throughout the 18-week infection period.
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PMID:The expression of the Helicobacter pylori genes ureA and nap is higher in vivo than in vitro as measured by quantitative competitive reverse transcriptase-PCR. 1193 67

Soybean (Glycine max [L.] Merrill) mutant aj6 carries a single recessive lesion, aj6, that eliminates ubiquitous urease activity in leaves and callus while retaining normal embryo-specific urease activity. Consistently, aj6/aj6 plants accumulated urea in leaves. In crosses of aj6/aj6 by urease mutants at the Eu1, Eu2, and Eu3 loci, F(1) individuals exhibited wild-type leaf urease activity, and the F(2) segregated urease-negative individuals, demonstrating that aj6 is not an allele at these loci. F(2) of aj6/aj6 crossed with a null mutant lacking the Eu1-encoded embryo-specific urease showed that ubiquitous urease was also inactive in seeds of aj6/aj6. The cross of aj6/aj6 to eu4/eu4, a mutant previously assigned to the ubiquitous urease structural gene (R.S. Torisky, J.D. Griffin, R.L. Yenofsky, J.C. Polacco [1994] Mol Gen Genet 242: 404-414), yielded an F(1) having 22% +/- 11% of wild-type leaf urease activity. Coding sequences for ubiquitous urease were cloned by reverse transcriptase-polymerase chain reaction from wild-type, aj6/aj6, and eu4/eu4 leaf RNA. The ubiquitous urease had an 837-amino acid open reading frame (ORF), 87% identical to the embryo-specific urease. The aj6/aj6 ORF showed an R201C change that cosegregated with the lack of leaf urease activity in a cross against a urease-positive line, whereas the eu4/eu4 ORF showed a G468E change. Heteroallelic interaction in F(2) progeny of aj6/aj6 x eu4/eu4 resulted in partially restored leaf urease activity. These results confirm that aj6/aj6 and eu4/eu4 are mutants affected in the ubiquitous urease structural gene. They also indicate that radical amino acid changes in distinct domains can be partially compensated in the urease heterotrimer.
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PMID:Interallelic complementation at the ubiquitous urease coding locus of soybean. 1291 38

The chemical constituents of some species of Euphorbia, which grow mostly in semi-desert areas in Iran and on the Alborz Mountains in the north of Tehran, have been found to include chemotaxonomically important myrsinane diterpenoids and cycloartane triterpenoids. The Euphorbia plants collected in province of Azarbaijan in the northwestern part of Iran contained mostly derivatives of skin-irritating ingenol esters. Some of the diterpenoids with myrsinane carbon skeleton inhibited enzymes such as alpha-glycosidase, urease, HIV-1 reverse transcriptase, and prolyl endopeptidase. They also showed analgesic and DNA-damaging activities. The present review describes the chemistry and biological activity of several compounds isolated from different species of Iranian Euphorbia: diterpenoids with myrsinane skeletons, flavonoids, tannins, alkanes, sterols, mono-, sesqui- and triterpenoids, skin-irritating and tumor-promoting latexes and their active ingenol diterpenoids.
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PMID:Chemistry and biological activity of secondary metabolites in Euphorbia from Iran. 1688 6

A general overview is presented of the changes in the genetic expression along a time curve through the first 20 min after acidification to pH 4.5 of exponentially growing cultures of the food pathogenic strain Staphylococcus aureus 50583. A newly developed method for statistical significance testing was used to detect significant gene expression responses. Most responses showed an increase or decrease from time zero to 10 min after acidification, and then generally a stabilization in expression level from 10 to 20 min. Increased urease activity appeared to be an important factor in the acid defence, along with proton excretion by NADH dehydrogenase and macromolecule repair mechanisms. Oxidative-stress responses, such as increased expression of thioredoxin genes and upregulation of pentose phosphate pathway genes to generate more reducing power, were also induced. A general reduction in the expression of genes encoding ribosomal proteins and genes involved in nucleotide synthesis, as well as fatty acid and lipoprotein metabolism, reflected the lowered growth rate after acidification. The pH shock did not appear to trigger major virulence responses or biofilm formation. Metal ion regulation and transport were affected by the acid shock, and production of several cofactors such as molybdopterin was increased. Many of the presented observations could be explained, while some represent still-unknown mechanisms. The patterns of regulation were confirmed by quantitative reverse transcriptase PCR (QRT-PCR). Together, these results showed the main responses of S. aureus and will be a good starting point for future, more specific, in-depth studies of specific gene responses that occur in conjunction with the acid-stress defence of S. aureus.
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PMID:Acid-shock responses in Staphylococcus aureus investigated by global gene expression analysis. 1760 73

It was recently shown that, as in yeast, alcohols selectively increase the hemolytic properties of certain staphylococci strains. This phenomenon has been called 'microbial alcohol-conferred hemolysis'(MACH). Here we present the changes in gene expression by Staphylococcus aureus 8325-4, in response to ethanol. Ethanol upregulated the expression of multiple toxins and increase the pathogen potential of S. aureus strain 8325-4. Ethanol also increased the level of genes considered necessary for production and viability of biofilm, such as: icaAD, sdrDE, pyr, and ure. Increased urease activity appeared to be an important factor in the ethanol response along with macromolecule repair mechanisms. Oxidative-stress responses, such as increased expression of sodA1, sodA2 and upregulation of zinc-containing alcohol dehydrogenase, alcohol-acetaldehyde dehydrogenase (adhE) and two aldehyde dehydrogenases (aldA1, aldA2), which can generate more reducing power, were also induced. Upregulation of fatty acid metabolism appears to be important in enabling the bacteria to handle excess amounts of ethanol which ultimately may lead to synthesis of lytic lypids. The patterns of regulation were confirmed by quantitive reverse transcriptase PCR (QRT-PCR). These results, taken together, suggest that exposure to ethanol increases pathogenic traits and induce oxidative-stress responses.
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PMID:Global gene expression in Staphylococcus aureus following exposure to alcohol. 1990 May 30