Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antigenic reactivity of the three polymerase proteins PB1, PB2, and PA of type A influenza viruses of animal and human origin were analysed by radioimmunoprecipitation using monospecific antisera. Each of the polymerase monospecific antisera made against the polymerase proteins of the human A/WSN/33 (H1N1) influenza virus reacted efficiently with the homologous proteins of all the known thirteen HA subtype viruses of avian influenza virus, three subtypes of human influenza virus, swine and equine influenza viruses. This broad reactivity of each of the antisera indicated that the polymerase proteins are antigenically related among the type A influenza viruses and therefore can be considered as type specific antigens similar to the other viral internal proteins nucleoprotein (NP) and matrix protein (M). No electrophoretic migrational heterogeneity was found among the PB2 proteins of different subtype viruses, whereas PB1 protein exhibited minor variation. However, PA protein from among various viral subtypes showed considerable heterogeneity. Each of the polymerase antisera also immunoprecipitated additional antigenically related polypeptides with distinct electrophoretic mobilities from cells infected with each of the influenza viral subtypes.
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PMID:Antigenic reactivity and electrophoretic migrational heterogeneity of the three polymerase proteins of type A human and animal influenza viruses. 235 72

Interferons alpha and beta induce an efficient antiviral state against influenza virus in mouse cells that possess the Mx gene, but not in mouse cells that lack this gene. In Mx-containing cells treated with interferon the amount of viral mRNA synthesized as a result of primary transcription is drastically reduced. Only two viral mRNAs could be detected by Northern analysis and by translating the poly(A)+ RNA from infected cells in wheat germ extracts: a reduced amount of the mRNA for nonstructural protein 1 and an even lower amount of the mRNA for the matrix protein. The other viral mRNAs were not made in detectable amounts. In addition, the rate of viral mRNA synthesis catalyzed by the inoculum transcriptase, measured by in vitro RNA synthesis catalyzed by permeabilized cells, was severely inhibited. In contrast, interferon treatment of cells lacking the Mx gene had little or no effect on either the steady-state level or the rate of synthesis of viral mRNAs made by the inoculum transcriptase. These results indicate that the interferon-induced Mx gene product, a 75,000-molecular-weight protein that accumulates in the nucleus, inhibits influenza viral mRNA synthesis which occurs in the nucleus. No Mx-specific effect acting directly on viral protein synthesis in the cytoplasm was observed.
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PMID:Inhibition of influenza viral mRNA synthesis in cells expressing the interferon-induced Mx gene product. 241 49

The matrix protein (M1) of influenza A virus, which has a critical role in viral assembly and can inhibit the viral transcriptase complex, has the ability to bind RNA. The RNA-binding property of M1 is specific for single-stranded RNA, like that of influenza nucleoprotein (NP) and shows similar sensitivity to pH and to salt concentration. M1:RNA complexes are stable, once formed, to competition from excess single-stranded RNA. The possible location of the RNA-binding regions in the M1 protein is discussed.
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PMID:RNA-binding properties of influenza A virus matrix protein M1. 247 6

The complete sequence of the gene encoding the matrix protein (M) of human parainfluenza virus type 3 (PIV-3) was determined from cDNA clones and from primer extension dideoxy sequencing of the viral genome. The M mRNA is 1150 nucleotides in length, exclusive of polyadenylate, and codes for a protein of 353 amino acids, having a calculated molecular weight of 39,480. The M protein of PIV-3 was found to have a high degree of sequence homology with that of a closely related paramyxovirus, Sendai virus, and to a lesser extent it contained sequence homology with two more distant paramyxoviruses, measles virus and canine distemper virus. We also determined the sequences of the intergenic junctions for the first four genes of PIV-3: NP, P, M, and F. Comparison of these sequences yielded a consensus mRNA start sequence of 5'-AGGANNAAAGA-3', an mRNA end sequence of 5'-UAAGAAAAA-3', and an intergenic sequence of 5'-CUU-3'. The end sequence of the M gene is unusual in that it contains an eight base insertion prior to the A5 tract found in the consensus sequence. This disruption appears to cause a high frequency of readthrough by the viral transcriptase at this junction.
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PMID:Complete nucleotide sequence of the matrix protein mRNA and three intergenic junctions of human parainfluenza virus type 3. 302 66

Ribonucleoprotein complexes isolated from measles virus-infected HeLa cells contained an RNA-dependent RNA polymerase activity that catalyzed the incorporation of ribonucleotides into ribonucleic acid. The ribonucleoprotein complexes were composed of measles virus nucleoprotein, phosphoprotein, and a large protein, as well as viral RNA. The kinetics of RNA synthesis at different temperatures, time intervals, and protein, ribonucleotide, and mono- and divalent cation concentrations were analyzed. Enzyme activity was maximum at 4 h at 25 degrees C in the presence of 100 mM Na+-2.5 mM Mg2+-1 mM ribonucleotides. Actinomycin D and alpha-amanitin had no effect on the enzyme activity. Addition of cytoplasmic extracts from uninfected HeLa cells to the reaction mixture did not increase the incorporation of ribonucleotides into RNA. The in vitro synthesized RNAs were characterize by slot blot analysis and quantitated by densitometer scanning. All mRNAs coding for the structural proteins of measles virus were synthesized. Nucleoprotein RNA was the most abundant species made, followed by phosphoprotein, hemagglutinin, fusion protein, matrix protein, and large-protein RNAs. The system described here resulted in the first efficient transcription of measles virus RNA and analysis of products.
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PMID:Characterization of in vitro transcription and transcriptional products of measles virus. 366 51

Sendai virions, disrupted in 2% Triton X-100 in 1 M KCl, were separated into nucleocapsids and envelope proteins by centrifugation. The nucleocapsids, representing 46% of the virion proteins, had a buoyant density of 1.29 gm/cm(3) in D(2)O sucrose. RNA-dependent transcriptase activity associated with them had a ninefold greater specific activity than transcriptase assayed in unfractionated detergent-disrupted virions. These enzyme-active nucleocapsids contained only two polypeptides, the largest virion polypeptide (molecular weight 75,000) and the nucleocapsid structure unit (molecular weight 60,000). Virion envelope proteins, either glycoproteins or nonglycosylated matrix protein, inhibited nucleocapsid-associated polymerase activity; brief heat denaturation abolished their inhibitory activity. Yeast RNA stimulated nucleocapsid-associated enzyme, suggesting that stimulatory polyanions act at the enzyme-template level.
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PMID:Sendai virion transcriptase complex: polyeptide composition and inhibition by virion envelope proteins. 435 18

Influenza viruses are spherical, about 1000 A in diameter, and consist of an as yet undefined central structure containing the eight negative-sense RNA molecules of the genome (1) in association with the transcriptase required for mRNA synthesis, an abundant nucleoprotein, and an equally abundant matrix protein. This core is surrounded by a membrane derived from the cell surface in a budding process by which newly formed viruses are released from the infected cell. During infection cell membranes are modified by the incorporation of newly synthesized virus membrane proteins, and the finally released viruses contain exclusively two different types of virus-specified glycoprotein, hemagglutinin and neuraminidase, and a proton channel protein, M2. All three of these molecules have been studied extensively, particularly the glycoproteins, and in this paper information on their structures and functions will be summarized and related to modifications in cellular membranes that occur during virus infection.
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PMID:Influenza viruses and cell membranes. 755 5

We have mapped the genome of lettuce necrotic yellows virus (LNYV), the type member of the genus cytorhabdovirus of the family Rhabdoviridae. We have cloned and sequenced all intergenic regions and the 3' leader and 5' trailer of the negative-sense, single-stranded RNA genome of LNYV. The LNYV genome appears to contain six genes, the five expected genes coding for the virion proteins, and a sixth gene of unknown function, as for sonchus yellow net virus (SYNV), a member of the genus nucleorhabdovirus. The proposed LNYV genomic map is 3'-N-4a-4b-M-G-L-5', where N is the nucleocapsid protein gene; 4a and 4b are two genes, one of which codes for the proposed phosphoprotein P and the other for a putative protein of unknown function; M is the proposed matrix protein gene; G is the proposed glycoprotein gene; and L is the proposed transcriptase gene. The different LNYV intergenic regions have highly conserved consensus sequences, which could be divided into three components: the sequences corresponding to the 3' end of the mRNAs, intergenic sequences of variable length, and the sequences corresponding to the 5' end of the mRNAs. A leader sequence of 84 nucleotides (nt) at the 3' end of the LNYV genomic RNA preceeded the N gene. A trailer sequence of 187 nt at the 5' end of the genomic RNA followed the L gene. A comparison between LNYV leader and trailer sequences revealed complementary 3' and 5' ends, which could give rise to a putative "panhandle" structure with a two bases overhang in the leader sequence. We have compared these sequences to the corresponding sequences of SYNV as well as to vesicular stomatitis virus (VSV) and rabies virus (RV), the type members of the vesiculovirus and lyssavirus genera, respectively, of animal rhabdoviruses. Homologies were found in the intergenic regions between LNYV, SYNV, VSV, and RV, at the 3' ends of the mRNAs. LNYV intergenic sequences were of variable lengths, as were those found in RV. The consensus sequences found at the 5' ends of LNYV mRNAs differed from the highly conserved consensus transcription start sequence UUGU/A found in SYNV, VSV, and RV. Conserved sequences were also found in the first 30 nt of the leader and the last 30 nt of the trailer, between LNYV, SYNV, VSV, and RV.
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PMID:Genomic organization of lettuce necrotic yellows rhabdovirus. 817 30

The Borna disease virus antigenome includes five major open reading frames (ORFs) which encode, from 5' to 3', the putative nucleoprotein (N), the phosphoprotein (P), the putative matrix protein (M), the major glycoprotein (G), and the RNA-dependent RNA polymerase (pol). Whereas the N and P ORFs are translated from monocistronic transcripts, the M, G, and pol ORFs are translated from polycistronic transcripts. Expression of the M, G, and pol ORFs is dependent upon differential splicing of two introns (intron 1, 94 nucleotides [nt]; intron 2, 1,294 nt). In vitro transcription-translation assays of wild-type and mutant sequences indicated that the G ORF is translated from an unspliced 2.8-kb RNA by leaky ribosomal scanning. Splicing of intron 1 enhances the translation of the G ORF by converting the M ORF into a 13-amino-acid minicistron, a structure that facilitates ribosomal reinitiation.
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PMID:Evidence for translation of the Borna disease virus G protein by leaky ribosomal scanning and ribosomal reinitiation. 918 36

Two maize cDNAs were isolated and sequenced that had open reading frames with approximately 37% amino acid identity to mammalian pyruvate dehydrogenase kinases. Both maize kinase sequences contain the five domains with conserved signature residues typical of procaryotic two-component histidine kinases. Sequence comparisons identified six other highly conserved motifs that are proposed to be specific to pyruvate dehydrogenase kinases. In addition, specific Trp and Cys residues are also invariant in these sequences. The maize cDNAs are 1332 (PDK1) and 1602 (PDK2) nucleotides in length, encoding polypeptides with calculated molecular masses of 38,867 and 41,327 Da that share 77% amino acid identity. Reverse transcriptase-polymerase chain reaction analysis with oligonucleotide-specific primers revealed a differential expression pattern for the two isoforms. PDK1 and PDK2 were expressed in Escherichia coli with N-terminal His6 tags to facilitate purification. The recombinant proteins migrated at 44 and 48 kDa, respectively, during SDS-polyacrylamide gel electrophoresis. Anti-PDK1 antibodies immunoprecipitated 75% of pyruvate dehydrogenase kinase activity from a maize mitochondrial matrix fraction, and recognized a matrix protein of 43 kDa. Recombinant PDK2, expressed as a fusion with the maltose-binding protein, inactivated kinase-depleted maize pyruvate dehydrogenase complex when incubated with MgATP, coincident with incorporation of 32P from [gamma-32P]ATP into the alpha subunit of pyruvate dehydrogenase.
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PMID:Molecular analysis of two pyruvate dehydrogenase kinases from maize. 975 1


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