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

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An in situ gel assay was applied to the study of double stranded RNA dependent RNase activity associated with reverse transcriptase (RT) of HIV-1 and murine leukemia virus. Polyacrylamide gels containing [32P] RNA/RNA substrate were used for electrophoresis of proteins under denaturing conditions. The proteins were renatured and in situ enzymatic degradation of 32P-RNA/RNA was followed. E. coli RNaseIII, but not E. coli RNaseH, was active in this in situ gel assay, indicating specificity of the assay to RNA/RNA dependent nucleases. Analysis of purified preparations of HIV-1 RT p66/p51 expressed in E. coli demonstrated an RNA/RNA dependent RNase activity comigrating with the large subunit (p66) of the enzyme. In addition, this activity of the RT was often accompanied by a contaminating RNA/RNA dependent RNase, with a molecular weight approximately 30,000 dalton identical to that of E. coli RNaseIII. As the p51 small subunit of HIV-1 RT and a mutant of RT p66/p51, at Glutamic acid #478, did not exhibit RNA/RNA dependent RNase activity, at least part of the active site of the RNA/RNA dependent RNase activity appeared to reside at the carboxy end of the molecule. As these RT proteins are also deficient of RNaseH, our results suggest overlapping or identical catalytic sites for degradation of the substrates RNA/DNA and RNA/RNA.
...
PMID:Characterization of the double stranded RNA dependent RNase activity associated with recombinant reverse transcriptases. 138 38

The complete RNA genome of turnip mosaic potyvirus (TuMV) was amplified by seven consecutive reverse transcriptase-polymerase chain reactions and cloned into pUC9. The viral RNA is 9830 nucleotides long and contains a single open reading frame (ORF) of 9489 bases encoding a large polyprotein of 3863 amino acids with a calculated M(r) of 358,000. The non-coding region (NCR) preceding the ORF is 129 nucleotides long and has a high AU content (70%). Its predicted secondary structure is characterized by a hairpin loop with a free energy loss of -69.9 kJ/mol. The termination codon is followed by an AU-rich NCR of 209 bases, excluding the poly(A) tail. Seven potential nuclear inclusion a proteinase (NIa-Pro) recognition heptapeptides are found in the polyprotein. Their sequences agree with consensus potyviral NIa-Pro cleavage sequences except for that at the 6K-VPg site, which is characterized by a glutamic acid residue preceding the hydrolysed peptide bond. The TuMV proteins are similar to their corresponding potyviral proteins.
...
PMID:The complete nucleotide sequence of turnip mosaic potyvirus RNA. 143 7

A collection of 47 strains of obligately anaerobic, gram-negative, rod-shaped bacteria that were isolated mainly from spoiled beer and pitching yeast was studied to learn more about their taxonomic positions. A new species of the genus Pectinatus, Pectinatus frisingensis, a new species of the genus Selenomonas, Selenomonas lacticifex, and a new genus comprising two species, Zymophilus raffinosivorans and Zymophilus paucivorans, are described. All of the strains contained directly cross-linked meso-diaminopimelic acid-containing peptidoglycan and in addition the diamine cadaverine or (rarely) putrescine. The diamine was covalently linked to the alpha-carboxyl group of D-glutamic acid in the peptide subunit of peptidoglycan. Lipid F was also found as a characteristic cellular compound. The phylogenetic relationships of members of these new species were examined by reverse transcriptase sequencing of 16S rRNA or by DNA-DNA hybridization studies or both. All of the organisms belong to the subdivision containing species with gram-negative cell walls within the phylum of gram-positive bacteria. This finding is in good agreement with the presence of a peptidoglycan that contains diamine.
...
PMID:Taxonomic study of anaerobic, gram-negative, rod-shaped bacteria from breweries: emended description of Pectinatus cerevisiiphilus and description of Pectinatus frisingensis sp. nov., Selenomonas lacticifex sp. nov., Zymophilus raffinosivorans gen. nov., sp. nov., and Zymophilus paucivorans sp. nov. 169 94

Human immunodeficiency virus type 1 (HIV-1) recombinant reverse transcriptase (RT) containing lysine (Lys) instead of glutamic acid (Glu) at position 138 proved fully resistant to the inhibitory effect of TSAO derivatives, but retained marked sensitivity to all other HIV-1-specific inhibitors investigated. In contrast, 181 Tyr-->Cys mutated RT lost sensitivity to all HIV-1-specific inhibitors. There was a close correlation between the sensitivity/resistance pattern of HIV-1-specific inhibitors against mutated (138 Glu-->Lys) recombinant HIV-1 RT and mutant virus strains selected for resistance against TSAO-m3T in cell culture and proven to contain the 138-Lys mutation as the sole mutation within the amino acid 50-270 region of their RT.
...
PMID:Sensitivity of (138 Glu-->Lys) mutated human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) to HIV-1-specific RT inhibitors. 751 68

By reverse transcriptase polymerase chain reaction on messenger RNA from human polymorphonuclear cells, we have isolated a sequence identical to the cDNA coding for intracellular interleukin 1 receptor antagonist (icIL-1ra), but containing an additional in-frame 63-bp sequence located three codons downstream of the translation start of icIL-1ra. This additional sequence is inserted between the first and second exon of the intracellular form, the latter of which is colinear with part of the first exon of the secreted form of IL-1ra. The additional sequence is coded by an extra exon located 2 kb downstream the first icIL-1ra-specific exon. The complementary DNA sequence of the alternatively spliced form of icIL-1ra shows that the predicted protein differs from classical icIL-1ra in the NH2 terminus by insertion of a leaderless sequence of 21 amino acids rich in glycine and glutamic acid residues. Transcripts coding for this new form of icIL-1ra were detected in activated fibroblasts, keratinocytes, and at low levels in myelomonocytic cells. The recombinant protein expressed in COS cells had an apparent molecular mass in sodium dodecyl sulfate polyacrylamide gel electrophoresis of 25 kD compared to 22 kD of classical icIL-1ra, and was mostly intracellular. The ability of this new form of icIL-1ra to inhibit IL-1 activity, in terms of induction of E-selectin and human immunodeficiency virus replication, was comparable to that of classical icIL-1ra. We propose to refer to this new form of icIL-1ra as icIL-1ra type II.
...
PMID:Cloning and characterization of a new isoform of the interleukin 1 receptor antagonist. 762 20

We recently reported that a newly discovered class of nucleoside analogues--[2',5'-bis-O-(tert-butyldimethylsilyl)- 3'-spiro-5''-(4''-amino-1'',2''-oxathiole-2'',2''-dioxide)]-beta-D - pentofuranosyl derivatives of pyrimidines and purines (designated TSAO)--are highly specific inhibitors of human immunodeficiency virus type 1 (HIV-1) and targeted at the nonsubstrate binding site of HIV-1 reverse transcriptase (RT). We now find that HIV-1 strains selected for resistance against three different TSAO nucleoside derivatives retain sensitivity to the other HIV-1-specific nonnucleoside derivatives (tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione (TIBO), 1-[(2-hydroxyethoxy)methyl]-6-phenylthiothymine, nevirapine, and pyridinone L697,661, as well as to the nucleoside analogues 3'-azido-3'-deoxythymidine, ddI, ddC, and 9-(2-phosphonylmethoxyethyl)adenine. Pol gene nucleotide sequence analysis of the TSAO-resistant and -sensitive HIV-1 strains revealed a single amino acid substitution at position 138 (Glu-->Lys) in the RT of all TSAO-resistant HIV-1 strains. HIV-1 RT in which the Glu-138-->Lys substitution was introduced by site-directed mutagenesis and expressed in Escherichia coli could not be purified because of rapid degradation. However, HIV-1 RT containing the Glu-138-->Arg substitution was stable. It lost its sensitivity to the TSAO nucleosides but not to the other HIV-1-specific RT inhibitors (i.e., TIBO and pyridinone). Our findings point to a specific interaction of the 4''-amino group on the 3'-spiro-substituted ribose moiety of the TSAO nucleosides with the carboxylic acid group of glutamic acid at position 138 of HIV-1 RT.
...
PMID:Human immunodeficiency virus type 1 (HIV-1) strains selected for resistance against the HIV-1-specific [2',5'-bis-O-(tert-butyldimethylsilyl)-3'-spiro- 5''-(4''-amino-1'',2''-oxathiole-2'',2''-dioxide)]-beta-D-pentofurano syl (TSAO) nucleoside analogues retain sensitivity to HIV-1-specific nonnucleoside inhibitors. 768 67

We have identified a new mutant Cu/Zn superoxide dismutase (SOD1) deduced from the nucleotide sequences of peripheral blood lymphocyte mRNA from Japanese patients with familial amyotrophic lateral sclerosis (FALS). Sequence analysis of reverse transcriptase-initiated PCR amplified mRNA revealed a heterozygosity indicative of one normal allele and one variant allele with a T-->A transversion. This base change led to replacement of valine by glutamic acid at position 7 of 153-residue SOD1 molecule, and produced a new restriction site for Alu I in the exon 1. Restriction fragment length polymorphism analysis confirmed the linkage of this mutation with this type of FALS. Both enzymatic activity and protein of the SOD1 were reduced in red blood cells from the patient.
...
PMID:A new variant Cu/Zn superoxide dismutase (Val7-->Glu) deduced from lymphocyte mRNA sequences from Japanese patients with familial amyotrophic lateral sclerosis. 798 May 16

We have created a temperature-sensitive (ts) mutant of human immunodeficiency virus type 1, using the technique of charge-cluster-to-alanine scanning mutagenesis to introduce specific changes into the integrase coding region. In the ts mutant virus, the lysine at amino acid 136 and the glutamic acid at amino acid 138 of integrase have been replaced with alanines (K136A/E138A). When K136A/E138A is synthesized at 35 degrees C, it replicates to a similar degree as wild-type virus during infection of CEM cells at 35 degrees C on the basis of syncytium formation, levels of core antigen, and reverse transcriptase activity. However, during infection at the nonpermissive temperature of 39.5 degrees C, K136A/E138A is capable of only one round of integration. Mutant virions formed at 39.5 degrees C do not integrate but are indistinguishable from wild-type virions when scored for activity of reverse transcriptase and correct expression and processing of Gag and Pol proteins. We demonstrate that the defect responsible for the ts phenotype of K136A/E138A is localized to a step after proviral formation and integrase protein synthesis but prior to particle maturation. It is the temperature at which the K136A/E138A virion is synthesized, not the temperature at which infection occurs, which determines the ability of the virus to integrate.
...
PMID:Identification and characterization of a temperature-sensitive mutant of human immunodeficiency virus type 1 by alanine scanning mutagenesis of the integrase gene. 798 62

HBY 097 [(S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3, 4-dihydroquinoxaline-2(1H)-thione] was selected from a series of quinoxalines as a nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (NNRTI). HBY 097 was shown to be a highly potent inhibitor of HIV-1 induced cell killing and HIV-1 replication in a variety of human cell lines as well as in fresh human peripheral blood lymphocytes and macrophages. The compound was also active against a variety of clinical isolates of HIV-1 including different HIV-1 subtypes and viruses resistant to 3'-deoxy-3'-azidothymidine. Mutant reverse transcriptases which arise as a consequence of treatment with other nonnucleoside inhibitors of HIV-1 reverse transcriptase were still inhibited by HBY 097 at relatively low concentrations. An HIV-1MN variant resistant to inhibition by HBY 097 displayed in the reverse transcriptase gene a mutation causing a substitution at position 190 of a glutamic acid for a glycine residue (G190 --> E), which is characteristic for quinoxaline derivatives. The drug was demonstrated to possess a favorable toxicity profile and to show good oral bioavailability in both mice and dogs. As a consequence of its outstanding properties, HBY 097 was selected for further development and is at present undergoing clinical trials.
...
PMID:Preclinical evaluation of HBY 097, a new nonnucleoside reverse transcriptase inhibitor of human immunodeficiency virus type 1 replication. 861 78

The alteration of a glutamic acid (E) to a glycine (G) amino acid residue at position 89 (E89G alteration) in the human immunodeficiency virus type 1 reverse transcriptase confers decreased susceptibility to several nucleoside analog inhibitors. Because the nonnucleoside inhibitor-binding pocket is adjacent to the deoxynucleoside triphosphate substrate-binding site, the impact of the E89G reverse transcriptase has decreased susceptibility to TIBO R82150, nevirapine, and to a lesser extent, delavirdine. Human immunodeficiency viruses bearing the same mutation displayed decreased susceptibility to inhibition by these compounds in a cell culture virus replication assay.
...
PMID:The nucleoside analog-resistant E89G mutant of human immunodeficiency virus type 1 reverse transcriptase displays a broader cross-resistance that extends to nonnucleoside inhibitors. 880 67


1 2 3 4 Next >>

---