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Three of the four nucleocapsid proteins of Marburg virus, NP, VP35, and L, are sufficient to mediate replication and transcription of Marburg virus-specific monocistronic minigenomes.

ABSTRACT: This paper describes the first reconstituted replication system established for a member of the Filoviridae, Marburg virus (MBGV). MBGV minigenomes containing the leader and trailer regions of the MBGV genome and the chloramphenicol acetyltransferase (CAT) gene were constructed. In MBGV-infected cells, these minigenomes were replicated and encapsidated and could be passaged. Unlike most other members of the order Mononegavirales, filoviruses possess four proteins presumed to be components of the nucleocapsid (NP, VP35, VP30, and L). To determine the protein requirements for replication and transcription, a reverse genetic system was established for MBGV based on the vaccinia virus T7 expression system. Northern blot analysis of viral RNA revealed that three nucleocapsid proteins (NP, VP35, and L) were essential and sufficient for transcription as well as replication and encapsidation. These data indicate that VP35, rather than VP30, is the functional homologue of rhabdo- and paramyxovirus P proteins. The reconstituted replication system was profoundly affected by the NP-to-VP35 expression ratio. To investigate whether CAT gene expression was achieved entirely by mRNA or in part by full-length plus-strand minigenomes, a copy-back minireplicon containing the CAT gene but lacking MBGV-specific transcriptional start sites was employed in the artificial replication system. This construct was replicated without accompanying CAT activity. It was concluded that the CAT activity reflected MBGV-specific transcription and not replication.

SUBMITTER: Muhlberger E

PROVIDER: S-EPMC110291 | biostudies-literature | 1998 Nov

REPOSITORIES: biostudies-literature

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Three of the four nucleocapsid proteins of Marburg virus, NP, VP35, and L, are sufficient to mediate replication and transcription of Marburg virus-specific monocistronic minigenomes.

Mühlberger E E Lötfering B B Klenk H D HD Becker S S

Journal of virology 19981101 11

This paper describes the first reconstituted replication system established for a member of the Filoviridae, Marburg virus (MBGV). MBGV minigenomes containing the leader and trailer regions of the MBGV genome and the chloramphenicol acetyltransferase (CAT) gene were constructed. In MBGV-infected cells, these minigenomes were replicated and encapsidated and could be passaged. Unlike most other members of the order Mononegavirales, filoviruses possess four proteins presumed to be components of the ...[more]

PMID: 9765419

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Project description:The Ebola virus and its close relative, the Marburg virus, both belong to the family Filoviridae and are highly hazardous and contagious viruses. With a mortality rate ranging from 23% to 90%, depending on the specific outbreak, the development of effective antiviral interventions is crucial for reducing fatalities and mitigating the impact of Marburg virus outbreaks. In this investigation, a virtual screening approach was employed to evaluate 2042 natural compounds for their potential interactions with the VP35 protein of the Marburg virus. Average and worst binding energies were calculated for all 20 poses, and compounds that exhibited binding energies <-6 kcal/mol in both criteria were selected for further analysis. Based on binding energies, only six compounds (Estradiol benzoate, INVEGA (paliperidone), Isosilybin, Protopanaxadiol, Permethrin, and Bufalin) were selected for subsequent investigations, focusing on interaction analysis. Among these selected compounds, Estradiol benzoate, INVEGA (paliperidone), and Isosilybin showed strong hydrogen bonds, while the others did not. In this study, the compounds Myricetin, Isosilybin, and Estradiol benzoate were subjected to a molecular dynamics (MD) simulation and free binding energy calculation using MM/GBSA analysis. The reference component Myricetin served as a control. Estradiol benzoate exhibited the most stable and consistent root-mean-square deviation (RMSD) values, whereas Isosilybin showed significant fluctuations in RMSD. The compound Estradiol benzoate exhibited the lowest ΔG binding free energy (-22.89 kcal/mol), surpassing the control compound's binding energy (-9.29 kcal/mol). Overall, this investigation suggested that Estradiol benzoate possesses favorable binding free energies, indicating a potential inhibitory mechanism against the VP35 protein of the Marburg virus. The study proposes that these natural compounds could serve as a therapeutic option for preventing Marburg virus infection. However, experimental validation is required to further corroborate these findings.

Project description:Marburg virus (MARV) encodes a nucleoprotein (NP) to encapsidate its genome by oligomerization and form a ribonucleoprotein complex (RNP). According to previous investigation on nonsegmented negative-sense RNA viruses (nsNSV), the newly synthesized NPs must be prevented from indiscriminately binding to noncognate RNAs. During the viral RNA synthesis process, the RNPs undergo a transition from an RNA-bound form to a template-free form, to open access for the interaction between the viral polymerase and the RNA template. In filoviruses, this transition is regulated by VP35 peptide and other viral components. To further understand the dynamic process of filovirus RNP formation, we report here the structure of MARV NPcore, both in the apo form and in the VP35 peptide-chaperoned form. These structures reveal a typical bilobed structure, with a positive-charged RNA binding groove between two lobes. In the apo form, the MARV NP exists in an interesting hexameric state formed by the hydrophobic interaction within the long helix of the NPcore C-terminal region, which shows high structural flexibility among filoviruses and may imply critical function during RNP formation. Moreover, the VP35 peptide-chaperoned NPcore remains in a monomeric state and completely loses its affinity for single-stranded RNA (ssRNA). The structural comparison reveals that the RNA binding groove undergoes a transition from closed state to open state, chaperoned by VP35 peptide, thus preventing the interaction for viral RNA. Our investigation provides considerable structural insight into the filovirus RNP working mechanism and may support the development of antiviral therapies targeting the RNP formation of filovirus.IMPORTANCE Marburg virus is one of the most dangerous viruses, with high morbidity and mortality. A recent outbreak in Angola in 2005 caused the deaths of 272 persons. NP is one of the most essential proteins, as it encapsidates and protects the whole virus genome simultaneously with self-assembly oligomerization. Here we report the structures of MARV NPcore in two different forms. In the MARV NP apo form, we identify an interesting hexamer formed by hydrophobic interaction within a long helix, which is highly conserved and flexible among filoviruses and may indicate its critical function during the virus RNP formation. Moreover, the structural comparison with the NP-VP35 peptide complex reveals a structural transition chaperoned by VP35, in which the RNA binding groove undergoes a transition from closed state to open state. Finally, we discussed the high conservation and critical role of the VP35 binding pocket and its potential use for therapeutic development.

Dataset Information

Three of the four nucleocapsid proteins of Marburg virus, NP, VP35, and L, are sufficient to mediate replication and transcription of Marburg virus-specific monocistronic minigenomes.

Publications

Three of the four nucleocapsid proteins of Marburg virus, NP, VP35, and L, are sufficient to mediate replication and transcription of Marburg virus-specific monocistronic minigenomes.

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