Biology subjects

Fujita-Fujiharu, Y.

Publications and source records attributed to Fujita-Fujiharu, Y..

3 recordsLinked to original sources

bioRxiv2024

Coatomer complex I is required for the transport of SARS-CoV-2 progeny virions from the endoplasmic reticulum-Golgi intermediate compartment

SARS-CoV-2 undergoes budding within the lumen of the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) and delivers progeny virions to the cell surface by employing vesicular transport. However, the molecular mechanisms remain poorly understood. Using three-dimensional electron microscopic analysis, such as array tomography and electron tomography, we found that virion-transporting vesicles possessed a coated protein on their membrane and demonstrated that the coated protein was coatomer complex I (COPI). During the later stages of SARS-CoV-2 infection, we observed a notable alteration in the distribution of COPI and ERGIC throughout the cytoplasm. Depletion of COPB2, a key component of COPI, led to the confinement of SARS-CoV-2 structural proteins in the perinuclear region, where progeny virions were accumulated within the ERGIC. While the expression levels of viral proteins within cells were comparable, this depletion significantly reduced the efficiency of virion release, leading to the significant inhibition of viral replication. Hence, our findings suggest COPI as a critical player in facilitating the transport of SARS-CoV-2 progeny virions from the ERGIC. Thus, COPI could be a promising target for the development of antivirals against SARS-CoV-2.

microbiology↗

bioRxiv2024

Structural basis of Ebola virus nucleocapsid assembly and functions

The Ebola virus, a member of the Filoviridae family, causes severe hemorrhagic fever in humans. Filamentous virions contain a helical nucleocapsid responsible for genome transcription, replication, and packaging into progeny virions. The nucleocapsid consists of a helical nucleoprotein (NP)-viral genomic RNA complex forming the core structure, to which VP24 and VP35 bind externally. Two NPs, each paired with a VP24 molecule, constitute a repeating unit. However, the detailed nucleocapsid structure remains unclear. Here, we determined the nucleocapsid-like structure within virus-like particles at 4.6 [A] resolution using single-particle cryo-electron microscopy. Mutational analysis identified specific interactions between the two NPs and two VP24s and demonstrated that each of the two VP24s in different orientations distinctively regulates nucleocapsid assembly, viral RNA synthesis, and intracellular transport of the nucleocapsid. Our findings highlight the sophisticated mechanisms underlying the assembly and functional regulation of the nucleocapsid and provide insights into antiviral development.

microbiology↗

bioRxiv2021

Structural insight into Marburg virus nucleoprotein-RNA complex formation

The nucleoprotein (NP) of Marburg virus (MARV), a close relative of Ebola virus (EBOV), encapsidates the single-stranded, negative-sense viral genomic RNA (vRNA) to form the helical NP-RNA complex. The NP-RNA complex serves as a scaffold for the assembly of the nucleocapsid that is responsible for viral RNA synthesis. Although appropriate interactions among NPs and RNA are required for the formation of nucleocapsid, the structural basis of the helical assembly remains largely elusive. Here, we show the structure of the MARV NP-RNA complex determined using cryo-electron microscopy at a resolution of 3.1 [A]. The structures of the asymmetric unit, a complex of an NP and six RNA nucleotides, was very similar to that of EBOV, suggesting that both viruses share common mechanisms for the nucleocapsid formation. Structure-based mutational analysis of both MARV and EBOV NPs identified key residues for the viral RNA synthesis as well as the helical assembly. Importantly, most of the residues identified were conserved in both viruses. These findings provide a structural basis for understanding the nucleocapsid formation and contribute to the development of novel antivirals against MARV and EBOV.

microbiology↗