Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

From Salmonella typhimurium LT2 hemA (delta-aminolevulinic acid requiring) 15 mutants were isolated which grew on the hydrophobic compound hemin. All had increased sensitivity to antibiotics such as vancomycin, bacitracin, novobiocin, erythromycin, rifampin, and oleandomycin, and were considered to be envelope mutants (Env-). Half the mutants were rough , based on altered bacteriophage sensitivity and deoxycholate sensitivity, whereas the remainder were smooth; three of the smooth mutants were studied in detail. They gave increased uptake of gentian violet but no increase in leakage of a periplasmic protein, RNase I. The total membranes and fractions from sucrose gradient centrifugations representing inner and outer membranes of the wild type and three mutants were examined by sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focussing - PAGE (IEF-PAGE). The major outer membrane proteins (molecular weights (MW)33 000, 34 000, 35 000, and 36 000) showed no or very little alterations in the Env- mutants. In SA1926 (env-52) one protein spot at MW 48 000, proven to be an outer membrane protein, was missing, whereas a new spot appeared nearby, and other proteins in this area of the gel were reduced. An Env+ transductant selected from this strain had the wild-type protein pattern restored. The two other Env- mutants had similar but not identical changes in protein composition.
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PMID:Isolation and characterization of hemin-permeable, envelope-defective mutants of Salmonella typhimurium. 701 21

A genomic DNA probe derived from the region immediately 3' of the clusters of integrated proviruses in the Mlvi-4 locus detects a 5.5-kb mRNA transcript which is specifically expressed in normal rat thymus and spleen. The same probe detects two tumor-specific mRNA transcripts 2.5 and 10 kb long, both of which are expressed only in tumors carrying a provirus in the Mlvi-4 locus. Sequence analysis of two cDNA clones (LE3a and B1.1) of the 2.5-kb tumor-specific mRNA, obtained from two independent tumors (6889 and B1), revealed that they are both derived from hybrid env/Mlvi-4 mRNA transcripts. The splicing of env to Mlvi-4 sequences linked a cryptic splice donor site at nucleotide position 6397 of the viral genome with a splice acceptor site in the region immediately 3' of the integrated provirus. The mRNA that gives rise to cDNA clone B1.1 terminates 1,005 bases 3' of the splice acceptor site without additional splicing. The mRNA that gives rise to cDNA clone LE3a terminates in the same site but undergoes differential splicing of an 81-base-long intron. The resulting mRNAs contain 247-amino-acid (clone B1.1) or 226-amino-acid (clone LE3a) open reading frames sharing 221 N-terminal amino acids, of which 207 are derived from the viral env gene and 14 are derived from Mlvi-4. RNase protection assays using 6889 tumor cell RNA and a probe derived from the cDNA clone LE3a detected both mRNA transcripts. More abundant of the two, however, was the one encoding the putative 247-amino-acid protein. Transient transfections of a construct expressing the RNA transcript defined by clone B1.1 into D17 cells led to the expression of an Env/Mlvi-4 fusion protein with an apparent molecular mass of 33 kDa. Given that cells with provirus insertions in the Mlvi-4 locus are selected and that retroviral env gene products may have profound effects in the biology of hematopoietic cells, we suggest that the detected fusion proteins may contribute to the growth of T-cell lymphomas.
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PMID:The activated Mlvi-4 locus in Moloney murine leukemia virus-induced rat T-cell lymphomas encodes an env/Mlvi-4 fusion protein. 796 83

The ovine lentiviruses cause encephalitis, pneumonia, and arthritis in sheep worldwide. Visna virus is a prototype of this family and the pathogenesis and molecular biology of the virus has been well characterized. The envelope proteins of visna virus are responsible for binding of virus to host cells and for causing cell fusion. The surface glycoprotein also elicits cellular and humoral immune responses to the virus, the former being thought to be responsible for eliminating infected cells as well as causing inflammatory lesions. In this study, transgenic sheep were constructed that expressed the envelope genes of visna virus under the control of the visna LTR to investigate the role of the env gene in the pathogenesis of lentiviral disease in its natural host. Three transgenic lambs were identified that contain the env transgene and express the envelope glycoproteins. These transgenic animals have remained healthy and expression of the viral gene has had no obvious deleterious effect. Expression of the visna envelope protein was demonstrated by cell fusion mediated by the envelope gene as well as by immunoprecipitation of the envelope proteins with monoclonal antibodies and immunofluorescence analyses of Env protein in cells. The target cell for visna virus replication in infected animals is the monocyte/macrophage. In natural infection, the level of viral gene expression in these cells increases with cell maturation. In the transgenic sheep, monocytes did not express the envelope glycoproteins until they differentiated into macrophages in vitro. Expression of the env mRNA in macrophages was quantitated by an RNase protection assay. In addition to expression in macrophages, the transgene was expressed by fibroblasts isolated from skin of the transgenic sheep. Expression of both the Env and Rev proteins was detected by immunoprecipitation and immunofluorescence. Two of the three lambs responded immunologically to the expression of the transgene by producing binding antibodies to the envelope glycoproteins. Thus, these transgenic sheep provide a model to study whether a lentivirus glycoprotein will prevent infection or modulate disease in its natural host after virus challenge.
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PMID:Development of transgenic sheep that express the visna virus envelope gene. 817 28

The majority of HIV-1-infected neonates and infants have a higher level of viremia and develop AIDS more rapidly than infected adults, including differences seen in clinical manifestations. To determine the mechanisms of HIV-1 infection in neonates vs. adults, we compared the replication kinetics of HIV-1 in neonatal (cord) and adult blood T lymphocytes and monocyte-derived macrophages (MDM) from seven different donors. We found that HIV-1 replicated 3-fold better in cord blood T lymphocytes compared with adult blood T lymphocytes and 9-fold better in cord MDM than adult MDM. We also show that this differential HIV-1 replication did not depend on differences in cell proliferative capabilities, cell surface expression of CD4, CXCR4, and CCR5, or in the amount of PCR products of reverse transcription, DNA synthesis, and translocation of preintegration complex into the nucleus in cord and adult T lymphocytes and MDM. Furthermore, using a single-cycle replication competent HIV-1-NL4-3-Env(-) luciferase amphotropic virus, which measures HIV-1 transcriptional activity independent of receptor and coreceptor expression, we found there was a 3-fold increase of HIV-1 LTR-driven luciferase expression in cord T lymphocytes compared with adult T lymphocytes and 10-fold in cord MDM than in adult MDM. The HIV-1 LTR-driven luciferase expression correlated with HIV-1 LTR transcription, as measured by ribonuclease protection assay. These data suggest that the increased replication of HIV-1 in cord blood compared with adult blood mononuclear cells is regulated at the level of HIV-1 gene expression, resulting in a higher level of viremia and faster disease progression in neonates than adults.
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PMID:Differential HIV-1 replication in neonatal and adult blood mononuclear cells is influenced at the level of HIV-1 gene expression. 1686 88

A known HIV-1-positive intravenous drug user was found to be human T cell lymphoma/leukemia virus-II (HTLV-II) DNA positive by polymerase chain reaction but seronegative in a screening ELISA. He was consistently DNA positive but took 2 years to fully seroconvert. Sequencing of the HTLV-II strain in his cultured T lymphocytes indicated that it is a prototypical type A strain with no major differences in the long terminal repeat DNA sequence, nor major amino acid differences in the Gag, Env, Tax, and Rex proteins. However, a mutation in its pol gene created a stop codon at amino acid 543 of the Pol protein, a region that encodes for the RNase function. This mutation may account for the subject's slow seroconversion.
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PMID:Delayed Seroconversion to HTLV-II Is Associated with a Stop-Codon Mutation in the pol Gene. 2789 35