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)

Canine and equine ferritin H and L subunit cDNA clones were obtained using reverse transcriptase-polymerase chain reaction (RT-PCR) and TA cloning from various tissues. Canine liver and spleen ferritin H subunit cDNA clones contained an open reading frame for the same 182-amino acid protein as that reported in canine brain ferritin H subunit cDNA although there were substitutions in the 3'-noncoding regions. Ferritin L subunit cDNA clones from canine liver, spleen, and kidney showed identical coding sequences encoding the 174-amino acid protein except for a single nucleotide substitution in kidney (C474G). The H subunit nucleotide sequences of equine leukocyte and spleen were identical to the fragment encoding the 181-amino acid protein in equine peripheral blood mononuclear cells, with the exception of one substitution seen in both leukocyte and spleen sequences (C234T). The nucleotide sequence of equine leukocyte ferritin L subunit showed 7 substitutions compared with the published equine liver L subunit sequence with two substitutions at positions 281 and 282 resulting in an amino acid substitution of P94L. The amino acid residues involved in the ferroxidase center and in iron nucleation were perfectly conserved in H and L subunits of canine and equine ferritins, respectively.
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PMID:Sequence analysis of canine and equine ferritin H and L subunit cDNAs. 1604 Mar 48

Partial hoxH genes of 2 cyanobacterial genera, including 5 strains of Arthrospira and 2 strains of Spirulina, were cloned and characterized. This gene encodes the large subunit of nickel-iron hydrogenase. The results showed that these genes comprised 1349 nucleotides in Arthrospira and 1343 nucleotides in Spirulina, respectively. The GC contents of hoxH were 45.7% to 47.3% in Arthrospira and up to 50.4% to 50.9% in Spirulina. The hoxH gene was demonstrated to be single copy by Southern analysis, and its transcription was verified by reverse transcriptase polymerase chain reaction in Arthrospira platensis FACHB341. The similarities of nucleotide sequences among the 5 strains of Arthrospira ranged from 95.7% to 99.8%, which are higher than those between Arthrospira and Spirulina (72.9-77.0%). However, similarity between the 2 Spirulina strains was only 72.5%, slightly lower than that between the 2 genera. A phylogenetic tree based on hoxH was constructed. All 5 strains of Arthrospira formed a monophyletic clade, which was highly supported by bootstrap value, while the 2 strains of Spirulina were separated into 2 different clades.
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PMID:Cloning and characterization of hoxH genes from Arthrospira and Spirulina and application in phylogenetic study. 1604 66

Aeromonas salmonicida subsp. salmonicida is the aetiological agent of furunculosis, a disease of farmed and wild salmonids. The type III secretion system (TTSS) is one of the primary virulence factors in A. salmonicida. Using a combination of differential proteomic analysis and reverse transcriptase (RT)-PCR, it is shown that A. salmonicida A449 induces the expression of TTSS proteins at 28 degrees C, but not at its more natural growth temperature of 17 degrees C. More modest increases in expression occur at 24 degrees C. This temperature-induced up-regulation of the TTSS in A. salmonicida A449 occurs within 30 min of a growth temperature increase from 16 to 28 degrees C. Growth conditions such as low-iron, low pH, low calcium, growth within the peritoneal cavity of salmon and growth to high cell densities do not induce the expression of the TTSS in A. salmonicida A449. The only other known growth condition that induces expression of the TTSS is growth of the bacterium at 16 degrees C in salt concentrations ranging from 0.19 to 0.38 M NaCl. It is also shown that growth at 28 degrees C followed by exposure to low calcium results in the secretion of one of the TTSS effector proteins. This study presents a simple in vitro model for the expression of TTSS proteins in A. salmonicida.
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PMID:Expression of and secretion through the Aeromonas salmonicida type III secretion system. 1662 45

Virulence factors of pathogenic Escherichia coli belonging to a recently emerged and disseminated clonal group associated with urinary tract infection (UTI), provisionally designated clonal group A (CGA), have not been experimentally investigated. We used a mouse model of ascending UTI with CGA member strain UCB34 in order to identify genes of CGA that contribute to UTI. iha was identified to be expressed by strain UCB34 in the mouse kidney using selective capture of transcribed sequences. iha from strain UCB34 demonstrated a siderophore receptor phenotype when cloned in a catecholate siderophore receptor-negative E. coli K-12 strain, as shown by growth promotion experiments and uptake of (55)Fe complexed to enterobactin or its linear 2, 3-dihydroxybenzoylserine (DHBS) siderophore derivatives. Siderophore-mediated growth promotion by Iha was TonB dependent. Growth and iron uptake were more marked with linear DHBS derivatives than with purified enterobactin. The reported phenotype of adherence to epithelial cells conferred by expressing iha from a multicopy cloning vector in a poorly adherent E. coli K-12 host strain was confirmed to be specific to iha, in comparison with other siderophore receptor genes. iha expression was regulated by the ferric uptake regulator Fur and by iron availability, as shown by real-time reverse transcriptase PCR. In a competitive infection experiment using the mouse UTI model, wild-type strain UCB34 significantly outcompeted an isogenic iha null mutant. Iha thus represents a Fur-regulated catecholate siderophore receptor that, uniquely, exhibits an adherence-enhancing phenotype and is the first described urovirulence factor identified in a CGA strain.
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PMID:Iha from an Escherichia coli urinary tract infection outbreak clonal group A strain is expressed in vivo in the mouse urinary tract and functions as a catecholate siderophore receptor. 1671 73

Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. It exhibits a high degree of aerotolerance and is able to survive in host cells, indicating that efficient oxidative stress protection mechanisms must be present in this organism. Manganese homeostasis plays a major role in oxidative stress protection in a variety of organisms; however, the transport and role of this metal in P. gingivalis is not well understood. Analysis of the genome of P. gingivalis W83 revealed the presence of two genes encoding homologs of a ferrous iron transport protein, FeoB1 and FeoB2. FeoB2 has been implicated in manganese accumulation in P. gingivalis. We sought to determine the role of the FeoB2 protein in metal transport as well as its contribution to resistance to oxygen radicals. Quantitative reverse transcriptase PCR analyses demonstrated that expression of feoB2 is induced in the presence of oxygen. The role of FeoB2 was investigated using an isogenic mutant strain deficient in the putative transporter. We characterized the FeoB2-mediated metal transport using (55)Fe(2+) and (54)Mn(2+). The FeoB2-deficient mutant had dramatically reduced rates of manganese uptake (0.028 pmol/min/10(7) bacteria) compared with the parental strain (0.33 pmol/min/10(7) bacteria) (after 20 min of uptake using 50 nM of (54)Mn(2+)). The iron uptake rates, however, were higher in the mutant strain (0.75 pmol/min/10(7) bacteria) than in the wild type (0.39 pmol/min/10(7) bacteria). Interestingly, reduced survival rates were also noted for the mutant strain after exposure to H(2)O(2) and to atmospheric oxygen compared to the parental strain cultured under the same conditions. In addition, in vitro infection of host cells with the wild type, the FeoB2-deficient mutant, and the same-site revertant revealed that the mutant had a significantly decreased capability for intracellular survival in the host cells compared to the wild-type strain. Our results demonstrate that feoB2 encodes a major manganese transporter required for protection of the bacterium from oxidative stress generated by atmospheric oxygen and H(2)O(2). Furthermore, we show that FeoB2 and acquisition of manganese are required for intracellular survival of P. gingivalis in host cells.
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PMID:Role of Porphyromonas gingivalis FeoB2 in metal uptake and oxidative stress protection. 1679 Jul 96

Metal ion availability in the human oral cavity plays a putative role in Streptococcus mutans virulence gene expression and in appropriate formation of the plaque biofilm. In this report, we present evidence that supports such a role for the DtxR-like SloR metalloregulator (called Dlg in our previous publications) in this oral pathogen. Specifically, the results of gel mobility shift assays revealed the sloABC, sloR, comDE, ropA, sod, and spaP promoters as targets of SloR binding. We confirmed differential expression of these genes in a GMS584 SloR-deficient mutant versus the UA159 wild-type progenitor by real-time semiquantitative reverse transcriptase PCR experiments. The results of additional expression studies support a role for SloR in S. mutans control of glucosyltransferases, glucan binding proteins, and genes relevant to antibiotic resistance. Phenotypic analysis of GMS584 revealed that it forms aberrant biofilms on an abiotic surface, is compromised for genetic competence, and demonstrates heightened incorporation of iron and manganese as well as resistance to oxidative stress compared to the wild type. Taken together, these findings support a role for SloR in S. mutans adherence, biofilm formation, genetic competence, metal ion homeostasis, oxidative stress tolerance, and antibiotic gene regulation, all of which contribute to S. mutans-induced disease.
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PMID:The SloR/Dlg metalloregulator modulates Streptococcus mutans virulence gene expression. 1681 76

The Fur protein is a global regulator of iron metabolism in many bacterial species. However, Fur homologs from some rhizobia appear not to mediate iron-dependent gene expression in vivo. Here, transcriptional profiling analysis showed that more than one-fourth of the genes within the iron stimulon of Bradyrhizobium japonicum were aberrantly controlled by iron in a fur mutant. However, Fur has only a modest role in regulating iron transport genes. Quantitative real time reverse transcriptase PCR measurements confirmed abnormal gene expression in iron-limited cells of the fur strain, thereby demonstrating that Fur must function under those conditions. The findings show that B. japonicum Fur is involved in iron-dependent gene expression, and support the conclusion that rhizobial Fur proteins have novel functions compared with well studied model systems.
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PMID:The Bradyrhizobium japonicum Fur protein is an iron-responsive regulator in vivo. 1703 78

Biomphalaria glabrata is an intermediate snail host for Schistosoma mansoni, a medically important schistosome. In order to identify transcripts involved in snail-schistosome interactions, subtractive cDNA libraries were prepared, using suppression subtractive hybridization (SSH) between a parasite-exposed schistosome-resistant and a susceptible strain of B. glabrata, and also between schistosome-exposed and unexposed snails from the resistant snail line. Separate libraries were made from both haemocytes and the haemopoietic organ. Subtraction was performed in both directions enriching for cDNAs differentially expressed between parasite-exposed resistant and susceptible samples and up or down-regulated in the resistant line after challenge. The resulting eight libraries were screened and eight genes, differentially expressed between the haemocytes of resistant and susceptible snail strains, were identified and confirmed with reverse transcriptase PCR, including two transcripts expected to be involved in the stress response mechanism for regulating the damaging oxidative burst pathways involved in cytotoxic killing of the parasite: the iron-storage and immunoregulatory molecule, ferritin, and HtrA2, a serine protease involved in the cellular stress response. Transcripts with elevated levels in the resistant strain, had the same expression patterns in the subtracted libraries and unsubtracted controls; higher levels in exposed resistant snails compared to susceptible ones and down-regulated in exposed compared with unexposed resistant snails. Differential expression of two of the transcripts with no known function from the susceptible strain, was independently confirmed in a repeat exposure experiment.
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PMID:Identification of genes involved in interactions between Biomphalaria glabrata and Schistosoma mansoni by suppression subtractive hybridization. 1708 33

Lead (Pb) is known to preferentially suppress the activation and development of type-1 CD4+ helper T cell (Th1) responses, whereas it enhances the development of type-2 CD4+ helper T cell (Th2) responses. The inhibition of interferon-gamma (IFNgamma) production has been demonstrated in vitro with a Th1 clone and DO11.10 ovalbumin-transgenic (OVA-tg) CD4+ T cells, and in vivo with wild-type and OVA-tg BALB/c mice; however, the mechanisms responsible for the Pb-induced downregulation of IFNgamma have not been reported. Here, we assessed the modulation of IFNgamma production at the mRNA and protein levels. Pb did not significantly affect IFNgamma mRNA expression by a Th1 clone or activated splenocytes, as measured by reverse transcriptase-polymerase chain reaction (RT-PCR), ribonuclease protection, and real-time RT-PCR. However, Pb did significantly lower the amount of IFNgamma protein in supernatants and cell lysates of antigen-activated T cells in comparison to stimulated controls, suggesting that the lower amounts of IFNgamma released into culture supernatants were not due to a blockage of secretion that gave rise to a cytoplasmic accumulation of IFNgamma. Pb inhibition also was not prevented by addition of zinc or iron. Pb did not enhance protein degradation of IFNgamma, in that lactacystin, an effective blocker of proteosomal proteolysis, did not prevent loss of IFNgamma; additionally, Pb did not accelerate loss of IFNgamma after cycloheximide treatment. Pb did, however, significantly suppress IFNgamma biosynthesis, as investigated using 35S-incorporation in pulse/chase experiments, although it did not suppress total protein synthesis, indicating that Pb selectively inhibits IFNgamma biosynthesis. Thus, Pb appears to selectively interfere with the translation of certain proteins, such as IFNgamma. IL-12 blocked Pb's preferential promotion of Th2 cells, but absence of STAT6 did not prevent the Pb skewing. Thus, Pb may modulate unique regulatory pathways.
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PMID:Posttranscriptional inhibition of interferon-gamma production by lead. 1716 72

A Salmonella genomic island 1 (SGI1) isogenic strain pair was constructed using Salmonella enterica serovar Typhimurium LT2 (ST LT2). Real-time quantitative reverse transcriptase PCR revealed detectable mRNA transcripts for all 44 putative ORFs encoded within the SGI1. The highest levels of transcripts observed in SGI1 encoded ORFs were found in genes conferring antibiotic resistance to ampicillin, streptomycin/spectinomycin, and sulphonamides. Abundant mRNA transcripts, relative to gapA, were also noted for one putative regulatory ORF and seven ORFs of unknown function encoded within SGI1, whose products could represent factors contributing to increases in virulence and/or fitness of the organism. DNA microarray analysis revealed the differential expression of known factors that contribute to virulence in many pathogens. Twenty-two chromosomal genes were significantly upregulated in ST LT2 harboring SGI1, which included increased expression of iron and sialic acid utilization genes. Decreased expression was noted for 15 genes in ST LT2 harboring SGI1, including genes involved in chemotaxis and motility. This is the first report examining gene expression within the SGI1, as well as its potential effect on global gene expression, and sets the foundation for future studies involving the effect of SGI1 in other Salmonella spp.
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PMID:The effect of the Salmonella genomic island 1 on in vitro global gene expression in Salmonella enterica serovar Typhimurium LT2. 1719 8


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