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:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rhabdoviridae are single stranded negative sense RNA viruses. The viral RNA condensed by the nucleoprotein (N), the phosphoprotein (P) and the large subunit (L) of the RNA-dependent RNA polymerase are the viral components of the transcription/replication machineries. Both P and N contain intrinsically disordered regions (IDRs) that play different roles in the virus life cycle. Here, we describe the modular organization of P based on recent structural, biophysical and bioinformatics data. We show how flexible loops in N participate in the attachment of P to the N-RNA template by an induced-fit mechanism. Finally, we discuss the roles of IDRs in the mechanism of replication/transcription, and propose a new model for the interaction of the L subunit with its N-RNA template.
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PMID:Structural disorder in proteins of the rhabdoviridae replication complex. 2045 Apr 82

The phosphoprotein P of non-segmented negative-sense RNA viruses is an essential component of the replication and transcription complex and acts as a co-factor for the viral RNA-dependent RNA polymerase. P recruits the viral polymerase to the nucleoprotein-bound viral RNA (N-RNA) via an interaction between its C-terminal domain and the N-RNA complex. We have obtained the structure of the C-terminal domain of P of Mokola virus (MOKV), a lyssavirus that belongs to the Rhabdoviridae family and mapped at the amino acid level the crucial positions involved in interaction with N and in the formation of the viral replication complex. Comparison of the N-RNA binding domains of P solved to date suggests that the N-RNA binding domains are structurally conserved among paramyxoviruses and rhabdoviruses in spite of low sequence conservation. We also review the numerous other functions of this domain and more generally of the phosphoprotein.
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PMID:The structure of the nucleoprotein binding domain of lyssavirus phosphoprotein reveals a structural relationship between the N-RNA binding domains of Rhabdoviridae and Paramyxoviridae. 2045 78

The RNA polymerase of influenza A virus is a host range determinant and virulence factor. In particular, the PB2 subunit of the RNA polymerase has been implicated as a crucial factor that affects cell tropism as well as virulence in animal models. These findings suggest that host factors associating with the PB2 protein may play an important role during viral replication. In order to identify host factors that associate with the PB2 protein, we purified recombinant PB2 from transiently transfected mammalian cells and identified copurifying host proteins by mass spectrometry. We found that the PB2 protein associates with the cytosolic chaperonin containing TCP-1 (CCT), stress-induced phosphoprotein 1 (STIP1), FK506 binding protein 5 (FKBP5), alpha- and beta-tubulin, Hsp60, and mitochondrial protein p32. Some of these binding partners associate with each other, suggesting that PB2 might interact with these proteins in multimeric complexes. More detailed analysis of the interaction of the PB2 protein with CCT revealed that PB2 associates with CCT as a monomer and that the CCT binding site is located in a central region of the PB2 protein. PB2 proteins from various influenza virus subtypes and origins can associate with CCT. Silencing of CCT resulted in reduced viral replication and reduced PB2 protein and viral RNA accumulation in a ribonucleoprotein reconstitution assay, suggesting an important function for CCT during the influenza virus life cycle. We propose that CCT might be acting as a chaperone for PB2 to aid its folding and possibly its incorporation into the trimeric RNA polymerase complex.
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PMID:Association of the influenza virus RNA polymerase subunit PB2 with the host chaperonin CCT. 2057 28

With the advent of efficient systems to propagate the hepatitis C virus (HCV) in cultured cells important new discoveries have been made. For instance, several molecules required for HCV infection of hepatocytes have been identified and first insights into the entry pathway have been gained. Ribonucleic acid (RNA) replication and virion assembly were found to be tightly linked to lipid metabolism and numerous host factors contributing to viral replication have been identified. Some of them such as cyclophilin A or microRNA-122 are attractive targets for antiviral therapy as are the viral serine-type protease residing in nonstructural protein 3 (NS3) and the NS5B RNA-dependent RNA polymerase. More recently, the viral phosphoprotein NS5A emerged as an additional and very promising target for selective therapy. These results illustrate the great progress that has been made in the HCV field and how this knowledge can be used to devise innovative strategies to counteract this pathogen.
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PMID:New insights into structure and replication of the hepatitis C virus and clinical implications. 2096 Mar 74

Measles is a highly contagious human disease caused by the measles virus (MeV). In this study, by proteomic analysis, we identified peroxiredoxin 1 (Prdx1) as a host factor that binds to the C-terminal region of the nucleoprotein (N; N(TAIL)) of MeV. Glutathione S-transferase (GST) pulldown experiments showed that the Prdx1-binding site overlapped with the MeV phosphoprotein (P)-binding site on N(TAIL) and that Prdx1 competed for the binding to N(TAIL) with the P protein, which is a component of RNA-dependent RNA polymerase (RdRp). Furthermore, RNA interference for Prdx1 resulted in a significant reduction in MeV growth in HEK293-SLAM cells. A minigenome assay indicated that Prdx1 suppression affected the viral RNA transcription and/or replication step. Relative quantification of viral RNA by real-time PCR (RT-PCR) showed that Prdx1 suppression not only reduced viral RNA transcription and replication but also enhanced polar attenuation in viral mRNA transcription. Surface plasmon resonance analysis showed that the binding affinity of Prdx1 to MeV-N was 40-fold lower than that of MeV-P to MeV-N, which suggested that Prdx1 might be involved in the early stage of MeV infection, when the expression level of Prdx1 was much higher than that of MeV-P. Since Prdx1 was expressed abundantly and constitutively in various cells, the results in this study indicate that Prdx1 is one of the inherent host factors implicated in MeV RNA synthesis.
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PMID:Peroxiredoxin 1 is required for efficient transcription and replication of measles virus. 2115 70

The genome of rabies virus encodes five proteins; the nucleoprotein, the phosphoprotein, the matrix protein, the glycoprotein, and the RNA-dependent RNA polymerase. Among these, the glycoprotein is the most important as it is the major contributor to pathogenicity and virus neutralizing antibody response. Keeping in mind that glycoprotein is the only protein exposed on the surface of virus and is thought to be responsible for the interaction with the cell membrane, it was attempted to target glycoprotein by a ligand polyethylene glycol 4000, which blocks its active site, as seen by molecular operating environment software, so that it may be possible to prevent the spread of virus into the host. The ligand polyethylene glycol 4000 was retrieved from Research Collaboratory for Structural Bioinformatics protein data bank by providing the glycoprotein sequence to the databank. In this study it was observed that the ligand was successfully docked on a major portion of antigenic site II of glycoprotein by mimicking the virus neutralizing antibodies. This knowledge may be important for the development of novel therapies for the treatment of rabies and other viral diseases in the future.
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PMID:Molecular docking studies with rabies virus glycoprotein to design viral therapeutics. 2121 60

Rabies virus (RABV) is a negative-stranded RNA virus. Its genome is tightly encapsidated by the viral nucleoprotein (N) and this RNA-N complex is the template for transcription and replication by the viral RNA-dependent RNA polymerase (L) and its cofactor, the phosphoprotein (P). We present molecular, structural, and cellular aspects of RABV transcription and replication. We first summarize the characteristics and molecular biology of both RNA synthesis processes. We then discuss biochemical and structural data on the viral proteins (N, P, and L) and their interactions with regard to their role in viral transcription and replication. Finally, we review evidence that rabies viral transcription and replication take place in cytoplasmic inclusion bodies formed in RABV-infected cells and discuss the role of this cellular compartmentalization.
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PMID:Rabies virus transcription and replication. 2160 Oct 39

The viral RNA-dependent RNA polymerase (vRdRp) of paramyxovirus consists of the large (L) protein and the phosphoprotein (P). P is heavily phosphorylated, and it is thought that the phosphorylation of P plays a role in regulating viral RNA synthesis. However, no phosphorylation site within the P protein in paramyxovirus has been identified as playing a positive role in viral RNA synthesis in virus infection. Using mass spectrometry analysis, the threonine residue at position 286 of P of parainfluenza virus 5 (PIV5) was found phosphorylated. Mutation of T286 to alanine (T286A), aspartic acid (T286D), or glutamic acid (T286E) reduced minigenome activity. Recombinant virus containing a mutation at the T286 position (rPIV5-P-T286A) grew slower than wild-type virus; viral mRNA synthesis and protein expression of rPIV5-P-T286A were delayed. Biochemical studies showed that the binding of NP or L protein with the P mutants or tetramer formation by the mutant P proteins was unaltered from that for wild-type P. While we failed to rescue rPIV5-P-T286E virus, several revertant viruses were obtained. All non-wild-type revertants had mutations at T286 and showed defects in both minigenome activity and viral growth. This is the first time that a phosphorylation site within the P protein in paramyxovirus has been found to play a positive role in viral mRNA synthesis and virus growth.
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PMID:Identification of a phosphorylation site within the P protein important for mRNA transcription and growth of parainfluenza virus 5. 2168 May 23

The rhabdoviruses have a non-segmented single stranded negative-sense RNA genome. Their multiplication in a host cell requires three viral proteins in addition to the viral RNA genome. The nucleoprotein (N) tightly encapsidates the viral RNA, and the N-RNA complex serves as the template for both transcription and replication. The viral RNA-dependent RNA polymerase is a two subunit complex that consists of a large subunit, L, and a non-catalytic cofactor, the phosphoprotein, P. P also acts as a chaperone of nascent RNA-free N by forming a N(0)-P complex that prevents N from binding to cellular RNAs and from polymerizing in the absence of RNA. Here, we discuss the recent molecular and structural studies of individual components and multi-molecular complexes that are involved in the transcription/replication complex of these viruses with regard to their implication in viral transcription and replication.
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PMID:Structural insights into the rhabdovirus transcription/replication complex. 2196 63

The minimal RNA synthesis machinery of non-segmented negative-strand RNA viruses comprises a genomic RNA encased within a nucleocapsid protein (N-RNA), and associated with the RNA-dependent RNA polymerase (RdRP). The RdRP is contained within a viral large (L) protein, which associates with N-RNA through a phosphoprotein (P). Here, we define that vesicular stomatitis virus L initiates synthesis via a de-novo mechanism that does not require N or P, but depends on a high concentration of the first two nucleotides and specific template requirements. Purified L copies a template devoid of N, and P stimulates L initiation and processivity. Full processivity of the polymerase requires the template-associated N protein. This work provides new mechanistic insights into the workings of a minimal RNA synthesis machine shared by a broad group of important human, animal and plant pathogens, and defines a mechanism by which specific inhibitors of RNA synthesis function.
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PMID:Mechanism of RNA synthesis initiation by the vesicular stomatitis virus polymerase. 2224 79


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