Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Uropathogenic Escherichia coli (UPEC), the principal cause of urinary tract infection in women, colonizes the gut as well as the genitourinary tract. Studies of mice inoculated with UTI89, a sequenced isolate, have revealed a complex life cycle that includes formation of intracellular bacterial communities (IBCs) in bladder urothelial cells. To understand how UPEC adapts to life in IBCs, we have used GeneChips and/or quantitative reverse transcriptase PCR to study UTI89 recovered from the distal gut of gnotobiotic mice and from IBCs harvested by laser capture microdissection from the bladder urothelium of infected C3H/HeJ female mice. Host responses were characterized in laser capture microdissected urothelial cells that do or do not contain IBCs. The results reveal components of ferric iron acquisition systems in UTI89 that are expressed at significantly higher levels in IBCs compared with the intestine, including the hemin receptor chuA (1,390 +/- 188-fold). Localized urothelial responses to IBCs help oppose bacterial salvage of host cell iron (e.g. up-regulation of Tfrc (transferrin receptor) and Lcn2 (lipocalin 2)), facilitate glucose import (e.g. Hk2 (hexokinase 2)), and maintain epithelial structural integrity (e.g. Ivl (involucrin) and Sbsn (suprabasin)). DeltachuA mutants produce significantly smaller IBCs compared with wild type UTI89. This difference was not observed in strains lacking sitA (ABC-type iron/manganese transporter subunit), iroN (salmochelin receptor), hlyA (alpha-hemolysin), or entF (enterobactin synthetase subunit). Together, these studies indicate that heme- and siderophore-associated iron play key roles in IBC development and provide a series of microbial and host biomarkers for comparing UPEC strains isolated from humans.
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PMID:Functional genomic studies of uropathogenic Escherichia coli and host urothelial cells when intracellular bacterial communities are assembled. 1750 65

Iron (Fe) is an important trace element found in nearly all organisms, and is used as a cofactor in many biological reactions. One role for Fe in some invertebrates is in stabilization of extracellular matrices. The human blood fluke, Schistosoma japonicum, is responsible for significant human disease in developing and tropical nations. Disease in humans arises from host immunological reaction to parasite eggs that lodge in tissues. Schistosomes require Fe for development in their hosts, and store abundant Fe in vitelline (eggshell-forming) cells of the female system. The understanding of Fe metabolism and functionality are aspects of its biology that may be exploited in future therapeutics. The biology of Fe stores in vitelline cells of S. japonicum was investigated to illuminate possible functions of this element in early development of these parasites. Vitelline Fe is stored in yolk ferritin that is upregulated in females and is also expressed at low levels in egg-stages and adult males. Laser microdissection microscopy, coupled with reverse transcriptase- and real time-PCR amplification of schistosome ferritin sequences, confirmed that the vitelline cells are the likely progenitor cells of yolk ferritin. Assessment of Fe concentrations in whole male and whole female adult worms, eggs and purified eggshells by colorimetric assays and mass spectroscopy demonstrated higher levels of Fe in the female parasite, but also high levels of the element in whole parasite eggs and purified eggshell. Qualitative energy dispersive spectroscopy of purified eggshells, revealed that Fe is abundant in the eggshell, the matrix of which is composed of heavily cross-linked eggshell precursor proteins. Thus, vitelline stores of Fe are implicated in eggshell cross-linking in platyhelminths. These observations emphasise the importance of Fe in schistosome metabolism and egg formation and suggest new avenues for disruption of egg formation in these pathogenic parasites.
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PMID:Tracking the fate of iron in early development of human blood flukes. 1755 9

Cupriavidus metallidurans strain CH34 is a highly metal-resistant bacterium that contains 11 sigma factors of the extracytoplasmic function (ECF) protein family, which can be subgrouped into the ECF:FecI 1, ECF:FecI 2, ECF:RpoE and '(ECF)' clusters. To analyze the contribution of these 11 sigma factors to metal resistance, upregulation of the respective genes was measured by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR). As determined by RT-PCR, the ECF sigma factor genes were part of two- to tetra-cistronic operons, each containing genes for the sigma factor plus one or two antisigma factors. The three sigma factors RpoJ, RpoK and RpoI (ECF:FecI 1 cluster) were upregulated by Cu(II) and Ni(II), and under conditions of iron depletion. The other 8 ECF sigma factor genes were not induced by iron depletion. Strong upregulation of rpoJ and rpoK under iron depletion in a DeltarpoI mutant strain and close vicinity of rpoI to genes involved in iron siderophore metabolism marked RpoI as the primary ECF sigma factor for siderophore-mediated iron uptake. Genes for RpoO, RpoL and RpoM (ECF:FecI 2 cluster) were not upregulated by transition metal cations and influenced metal resistance only weakly. Concerning the two '(ECF)' group proteins, rpoQ was strongly upregulated by Cu(II) and deletion of rpoR led to a small decrease in copper resistance. Of the three ECF:RpoE-encoding genes, rpoP was not transcribed under the conditions tested, cnrH was upregulated by Ni(II) and essential for nickel resistance as known before. RpoE was required for full metal resistance of C. metallidurans. None of these 11 sigma factors was essential for metal resistance mediated by the cobalt, zinc and cadmium resistance determinant czc, or for its expression. However, RpoI was essential for siderophore production in C. metallidurans, and, in addition to the known role of CnrH in nickel resistance, RpoE, RpoI, RpoJ, RpoK and maybe also RpoQ are required for the outstanding transition metal resistance of this bacterium.
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PMID:Contribution of extracytoplasmic function sigma factors to transition metal homeostasis in Cupriavidus metallidurans strain CH34. 1758 71

The nucleotide sequence from the genome of Moraxella catarrhalis ATCC 43617 was annotated and used both to assess the metabolic capabilities and limitations of this bacterium and to design probes for a DNA microarray. An absence of gene products for utilization of exogenous carbohydrates was noteworthy and could be correlated with published phenotypic data. Gene products necessary for aerobic energy generation were present, as were a few gene products generally ascribed to anaerobic systems. Enzymes for synthesis of all amino acids except proline and arginine were present. M. catarrhalis DNA microarrays containing 70-mer oligonucleotide probes were designed from the genome-derived nucleotide sequence data. Analysis of total RNA extracted from M. catarrhalis ATCC 43617 cells grown under iron-replete and iron-restricted conditions was used to establish the utility of these DNA microarrays. These DNA microarrays were then used to analyze total RNA from M. catarrhalis cells grown in a continuous-flow biofilm system and in the planktonic state. The genes whose expression was most dramatically increased by growth in the biofilm state included those encoding a nitrate reductase, a nitrite reductase, and a nitric oxide reductase. Real-time reverse transcriptase PCR analysis was used to validate these DNA microarray results. These results indicate that growth of M. catarrhalis in a biofilm results in increased expression of gene products which can function not only in energy generation but also in resisting certain elements of the innate immune response.
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PMID:Metabolic analysis of Moraxella catarrhalis and the effect of selected in vitro growth conditions on global gene expression. 1762 Mar 51

Aldehyde oxidase (AO, EC 1.2.3.1) is a molybdenohydroxylase that is considered to catalyze the last step of abscisic acid (ABA) and indole-3-acetic acid (IAA) synthesis. Three cDNAs encoding aldehyde oxidase proteins in Pisum sativum (cv. Little Marvel) were obtained based on RT-PCR (reverse transcriptase-polymerase chain reaction) strategy. The cloned genes, designated as PsAO1, PsAO2 and PsAO3, are 4630, 4347, 4600 bp in length, respectively, and show high sequence identity to each other and to aldehyde oxidases from other plant species. The deduced PsAO1, PsAO2, and PsAO3 proteins are 1373, 1367, 1367 amino acids in length, respectively, and contain consensus sequences for two iron-sulfur centers, a FAD binding domain, and a molybdenum cofactor (Moco) binding domain. PsAO1 and PsAO2 were mainly expressed in leaves of seedlings and young leaves of adult plants, while the highest PsAO3 transcript level was observed in aging leaves and matured seeds. PsAO2 mRNA was not affected by salinity or ammonium treatment, whereas the transcript level of PsAO3 increased significantly under both stress conditions, with the most pronounced changes in aging leaves, fully expanded leaves and roots. The PsAO1 transcript level was enhanced only in the presence of ammonium in the nutrient medium, but not under salinity. Based on the molecular mass of the deduced proteins and on organ-specific gene expression, studied both under control and stress conditions, the contribution of each PsAO cDNA in the formation of the previously described three dimeric pea AO isoforms and the possible involvement of the PsAO3 in abscisic acid (ABA) synthesis is discussed.
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PMID:Molecular cloning, characterization and expression analysis of three aldehyde oxidase genes from Pisum sativum L. 1800 24

The hepatitis B virus (HBV) reverse transcriptase (RT) plays a multitude of fundamental roles in the viral life cycle and is the key target in the development of anti-HBV chemotherapy. We report here that the endogenous small molecule iron protoporphyrin IX (hemin) and several related porphyrin compounds potently blocked a critical RT interaction with the viral RNA packaging signal/origin of replication, called epsilon. As RT-epsilon interaction is essential for the initiation of viral reverse transcription, which is primed by RT itself (protein priming), the porphyrin compounds dramatically suppressed the protein-priming reaction. Further studies demonstrated that these compounds could target the unique N-terminal domain of the RT protein, the so-called terminal protein. Hemin and related porphyrin compounds thus represent a novel class of agents that can block HBV RT functions through a mechanism and target that are completely distinct from those of existing anti-HBV drugs.
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PMID:Inhibition of hepadnavirus reverse transcriptase-epsilon RNA interaction by porphyrin compounds. 1809 91

Capsular polysaccharide (CPS) is a major virulence factor in Vibrio vulnificus, and encapsulated strains have an opaque, smooth (OpS) colony morphology, while nonencapsulated strains have a translucent, smooth (TrS) colony morphology. Previously, we showed that OpS and TrS parental strains can yield a third colony type, rugose (R), and that the resulting strains, with the OpR and TrR phenotypes, respectively, form copious biofilms. Here we show that while OpR and TrR strains both produce three-dimensional biofilm structures that are indicative of rugose extracellular polysaccharide (rEPS) production, OpR strains also retain expression of CPS and are virulent in an iron-supplemented mouse model, while TrR strains lack CPS and are avirulent. Chlorine resistance assays further distinguished OpR and TrR isolates as exposure to 3 microg/ml NaOCl eradicated both OpS and OpR strains, while both TrS and TrR strains survived, but at rates which were significantly different from one another. Taken together, these results further emphasize the importance of CPS for virulence of V. vulnificus and establish a correlation between CPS expression and chlorine sensitivity in this organism. Using reverse transcriptase PCR, we also identified a nine-gene cluster associated with both CPS and rEPS expression in V. vulnificus, designated the wcr (capsular and rugose polysaccharide) locus, with expression occurring primarily in R variants. The latter results set the stage for characterization of functional determinants which individually or collectively contribute to expression of multiple EPS forms in this pathogen.
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PMID:Further characterization of Vibrio vulnificus rugose variants and identification of a capsular and rugose exopolysaccharide gene cluster. 1821 74

During pancreatic islet transplantation, delayed and insufficient revascularization can deprive islets of oxygen and nutrients, resulting in cell death and early graft failure. Deferoxamine (DFO), an iron chelator, increases vascular endothelial growth factor (VEGF) expression in cells. The aim of this work was to study the effect of DFO on beta-cell and pancreatic islet viability as well as VEGF expression. beta-cell lines from rat insulinoma (Rin m5f) and primary cultures of pancreatic islets from Wistar rats were incubated with DFO (10, 100, and 1000 micromol/L). The viability was evaluated using fluorescein diacetate/propidium iodide for dying pancreatic islets and using cell titers for Rin m5f. Expression of VEGF messenger RNA (mRNA) was quantified using reverse transcriptase polymerase chain reaction (RT-PCR). Finally, VEGF secretion was determined using enzyme-linked immunosorbent assays at 1 to 3 days after treatment. The addition of 10 micromol/L of DFO preserved Rin m5F viability at 24 hours after treatment (10 micromol/L; 101.33% +/- 5.66%; n = 7). However, 100 and 1000 micromol/L of DFO induced cell death (68.92% +/- 5.83% and 65.89% +/- 5.83%, respectively; n = 4). In the same way, viability of pancreatic islets in the presence of DFO was preserved. RT-PCR analysis showed stimulation of VEGF mRNA in the presence of 10 micromol/L of DFO in islets at 3 days after culture. Finally, 10 micromol/L of DFO stimulated secretion of VEGF 7.95 +/- 0.84 versus 1.80 +/- 1.10 pg/microg total protein with 10 micromol/L of DFO in rat islets at 3 days after culture, n = 3; P < .001). The use of DFO to stimulate VEGF expression and increase islet vascularization may be a realistic approach to improve islet viability during transplantation.
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PMID:Overexpression of vascular endothelial growth factor in vitro using deferoxamine: a new drug to increase islet vascularization during transplantation. 1837 6

Strains of Francisella tularensis secrete a siderophore in response to iron limitation. Siderophore production is dependent on fslA, the first gene in an operon that appears to encode biosynthetic and export functions for the siderophore. Transcription of the operon is induced under conditions of iron limitation. The fsl genes lie adjacent to the fur homolog on the chromosome, and there is a canonical Fur box sequence in the promoter region of fslA. We generated a Deltafur mutant of the Schu S4 strain of F. tularensis tularensis and determined that siderophore production was now constitutive and no longer regulated by iron levels. Quantitative reverse transcriptase PCR analysis with RNA from Schu S4 and the mutant strain showed that Fur represses transcription of fslA under iron-replete conditions. We determined that fslE (locus FTT0025 in the Schu S4 genome), located downstream of the siderophore biosynthetic genes, is also under Fur regulation and is transcribed as part of the fslABCDEF operon. We generated a defined in-frame deletion of fslE and found that the mutant was defective for growth under iron limitation. Using a plate-based growth assay, we found that the mutant was able to secrete a siderophore but was defective in utilization of the siderophore. FslE belongs to a family of proteins that has no known homologs outside of the Francisella species, and the fslE gene product has been previously localized to the outer membrane of F. tularensis strains. Our data suggest that FslE may function as the siderophore receptor in F. tularensis.
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PMID:fslE is necessary for siderophore-mediated iron acquisition in Francisella tularensis Schu S4. 1853 39

Treatment of salmonellosis with antibiotics is controversial and may prolong carriage and shedding. Therefore, this study sought to investigate if exposure to antimicrobials influences the expression of factors involved in virulence and host colonization. The effect of subinhibitory tetracycline treatment (16 microg/ml, 30 min) on a multi-drug resistant Salmonella Typhimurium DT104 strain was investigated using a targeted microarray. Real-time reverse transcriptase PCR was used to confirm and further assess transcription of 10 selected genes. An in vitro cell invasion assay was performed to assess the invasiveness of the tetracycline-treated isolate. Out of 323 genes, 11 were significantly up-regulated and four were down-regulated in the microarray assays. The hilD and hilA genes, both regulators of Salmonella Pathogenicity Island 1, were up-regulated. Other up-regulated genes included the fliC, fliD, motA and motB genes, involved in motility, the fur gene, an important regulator of iron acquisition systems and of acid tolerance. The drug-exposed replicates showed a 2.5-fold increase in intracellular bacteria over the non-exposed control in cell cultures. These findings suggest a drug-induced expression profile consistent with the early stages of Salmonella infection and invasion concomitant with an increased ability to invade epithelial cells in vitro.
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PMID:Subinhibitory concentrations of tetracycline affect virulence gene expression in a multi-resistant Salmonella enterica subsp. enterica serovar Typhimurium DT104. 1865 7


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