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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have cloned and determined the nucleotide sequences of the seventh gene of the Miyahara strain of mumps virus (MuV) encoding the L protein. The L gene is 6925 nucleotides in length and contains a single long open reading frame which is capable of coding for a protein of 2261 amino acids with a calculated molecular weight of 256,571 Da. The deduced amino acid sequence of the L protein of MuV showed significant homology with those of six other paramyxoviruses, human parainfluenza type 2 virus, Newcastle disease virus, Sendai virus, measles virus, human parainfluenza type 3 virus, and human respiratory syncytial virus. The predicted MuV L protein contained distinct elements thought to be essential for RNA polymerase activity. A noncoding sequence of 24 nucleotides downstream of the presumed polyadenylation site of the L gene showed significant complementarity with the leader sequence composed of 55 nucleotide at the 3' end of the genomic RNA.
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PMID:Molecular cloning and sequence analysis of the mumps virus gene encoding the L protein and the trailer sequence. 158 59

We have developed a cell-free system derived from measles virus-infected cells that supported the transcription and replication of measles virus RNA in vitro. The data suggest that tubulin may be required for these reactions, since an anti-beta-tubulin monoclonal antibody inhibited viral RNA synthesis and the addition of purified tubulin stimulated measles virus RNA synthesis in vitro. Tubulin may be a subunit of the viral RNA polymerase, since two different anti-tubulin antibodies, one specific for the beta- and another specific for the alpha-subunit of tubulin, coimmunoprecipitated the measles virus L protein as well as tubulin from extracts of measles virus-infected cells. Other experiments further implicated actin in the budding process during virus maturation, as there appeared to be a specific association of actin in vitro only with nucleocapsids that have terminated RNA synthesis, which is presumably a prerequisite to budding.
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PMID:Host cell proteins required for measles virus reproduction. 232 7

Synthesis of virus-specific RNAs in human HEP-2 and L-41 cells chronically infected with measles virus was studied in comparison with synthesis of viral RNA in acutely infected L-41 cells. The RNA, a component of RNP isolated from chronically infected cells, was shown to be represented mainly by "minus" chains and to contain 23-25% "plus"-RNA. It was demonstrated by blotting hybridization that 1 species of genomic RNA with a molecular weight of 5 megadaltons was synthesized in acute infection whereas in chronically infected cells a small amount of subgenomic RNAs was additionally detected in RNP. The level of virus genome transcription in chronically infected cells was 7-8 fold lower than that in acute infection. The RNA-transcriptase activity of RNP isolated from chronically infected HEP-2 and L-41 cells was also lower than RNP activity from acutely infected L-41 cells. The observed features of virus-specific RNA synthesis in chronically infected cells seem to be likely to play a role in the maintenance of virus persistence.
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PMID:[RNA analysis of the measles virus in a human cell culture of the chronic infection]. 242 50

We have determined the nucleotide sequence of the measles virus (MV) L gene using a cDNA library encompassing the entire MV genome (J. Crowley et al. (1987) Intervirology, 28, 65-77). The L gene is 6639 nucleotides in length, and contains a single long open reading frame that could code for a protein of 247,611 kDa. Both the L gene and in particular the predicted L protein of MV bear substantial homology to their counterparts in Sendai virus and Newcastle disease virus, suggesting that the multifunctional nature of paramyxovirus L proteins imposes strong evolutionary constraints. The predicted MV L protein also contains distinct elements of a postulated ancestral RNA polymerase.
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PMID:Measles virus L protein evidences elements of ancestral RNA polymerase. 283 64

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

Sequences critical for the activity of the measles virus (MV) RNA polymerase in transcription and replication were analyzed using a MV genomic cDNA library containing overlapping clones encompassing the entire MV genome. Clones corresponding to the 3' and 5' ends of the MV genome were identified and sequenced, and these sequences were confirmed by primer extension experiments. Neither (+) nor (-) strand leader RNAs were detected in MV-infected cell extracts, using high specific activity riboprobes made form these clones. Clones representing each of the MV gene boundaries were also sequenced, and variations including point mutations, insertions, and deletions were noted. Together with the sequence of the MV L gene region, this report completes the sequence determination of the MV genome.
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PMID:Sequence variability and function of measles virus 3' and 5' ends and intercistronic regions. 336 90

Persistent measles virus infection of human HEp-2 or L-41 cells was accompanied by pronounced structural and functional changes of isolated intracellular viral nucleocapsids (NCs). The bulk of persistent NCs possessed altered conformation and a "string-of-beads" appearance, contained substantial amounts of subgenomic size RNAs, exhibited reduced transcriptase activity in vitro and lacked infectivity on transfection of susceptible cells. Immunogold staining revealed negligible binding of anti-P protein monoclonal antibodies to the "string-of-beads" type NCs, thus suggesting their non-functional state.
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PMID:Non-infectious morphologically altered nucleocapsids of measles virus from persistently infected cells. 359 84

To begin to map functional domains of the Sendai P-L RNA polymerase complex we wanted to characterize the P binding site on the Sendai L protein. Analysis of in vitro and in vivo P-L polymerase complex formation with carboxyl-truncations of the L protein showed that the N-terminal half of the protein was required. Site-directed mutagenesis of the Sendai virus L gene was employed to change amino acids within a highly conserved region of the N-terminal domain I from amino acids (aa) 348-379 singly or in pairs from the Sendai to the corresponding measles L sequence or to alanine. The mutant L proteins coexpressed with the viral P and NP proteins in mammalian cells were assayed for their ability to form the P-L complex and to synthesize RNA in vitro and showed a variety of defective phenotypes. While most of the mutant L proteins still formed the P-L polymerase complex, a change from serine to arginine at aa 368 and a three-amino-acid insertion at aa 379 virtually abolished both complex formation and RNA synthesis. Changes of aas 370 and 376-377 in the L protein gave only small decreases in viral RNA synthesis. Substitutions at either aas 349-350 or aas 354-355 and a three-amino-acid insertion at aa 348 in the L protein yielded enzymes that catalyzed significant transcription, but were defective in DI RNA replication, thus differentially affecting the two processes. Since DI leader RNA, but not genome RNA, was still synthesized by this class of mutants, the defect in replication appears to be in the ability of the mutant enzyme to package newly synthesized nascent RNA. Single changes at aas 362, 363, and 366 in the L protein gave enzymes with severely decreased overall RNA synthesis, although some leader RNA was synthesized, suggesting that they cannot transcribe or replicate past the leader gene. These studies have identified a region in conserved domain I critical for multiple functions of the Sendai virus L protein.
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PMID:Mutations in conserved domain I of the Sendai virus L polymerase protein uncouple transcription and replication. 749 60

The Sendai virus P and L proteins, the viral RNA polymerase, and the nucleocapsid protein, NP, synthesized in a transient mammalian expression system support the replication of Sendai virus defective interfering particle (DI) genome RNA in vitro. We have shown that the measles virus nucleocapsid protein, N, can substitute for the Sendai NP protein in genome synthesis. The chimeric product nucleocapsids, which contained Sendai RNA encapsidated with measles N protein, were atypical since they were sensitive to micrococcal nuclease digestion, unlike wild-type Sendai or measles nucleocapsids. The utilization of measles N protein required the endogenous Sendai virus RNA polymerase, since DI nucleocapsids free of polymerase were not replicated. Although both Sendai virus NP and P proteins and measles N and P proteins formed complexes when they were coexpressed, sedimentation analysis showed that measles N protein self-assembled and did not form a complex when expressed with the Sendai P protein. Furthermore, when the Sendai P-L polymerase complex was provided separately, measles N protein alone synthesized DI genome RNA in the absence of Sendai P protein. These data suggest that the self-assembled form of measles N protein functions in Sendai DI genome synthesis.
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PMID:Measles virus nucleocapsid protein can function in Sendai virus defective interfering particle genome synthesis in vitro. 783 42

The RNA polymerase of measles virus consists of two virus-encoded subunits, the L and P proteins with 2183 and 507 amino acids, respectively. When these proteins were coexpressed from plasmids in a mammalian expression system, a complex was formed as detected by the coimmunoprecipitation of the L protein with the P protein by anti-P antibodies. Pulse-chase experiments showed that complex formation increased the stability of the L protein. We have used the coimmunoprecipitation assay in conjunction with a series of C-terminal truncations of the L protein to map the region of the L protein which is involved in complex formation with the P protein. Mutant L proteins consisting of the N-terminal 1139, 916, 511, and 408 amino acids all bound to the P protein. An L protein truncation consisting of only the N-terminal 292 amino acids, which deleted part of the conserved domain I, however, did not bind the P protein. The data show that the N-terminal 408 amino acids of the L protein contain the P binding domain and suggest that domain I within this region of the L proteins of (-) strand RNA viruses may be important for RNA polymerase complex formation.
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PMID:An amino-proximal domain of the L protein binds to the P protein in the measles virus RNA polymerase complex. 797 55


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