Researchers Reveal Structure of Poxvirus Portal Complex That Controls Molecular Exchange
Researchers have determined the high-resolution structures of a portal complex and its pore embedded in the poxvirus core, revealing how the virus manages molecular traffic with the host cytoplasm. The pore is built from three viral proteins—E8, E6, and L3—and is geometrically and electrostatically suited to transport RNA while blocking double-stranded DNA and host immune sensors. This structural framework could inform the development of new antiviral therapies targeting poxviruses.
Using cryo-electron tomography and sub-tomogram averaging, scientists resolved the structure of the poxvirus portal complex at 7.1 Å resolution and its pore at 4.9 Å resolution, providing an atomic-level model of a key viral architecture. Poxviruses are unusual among viruses in that they carry out early gene transcription inside a protein-enclosed 'core' compartment within the host cell's cytoplasm, but the mechanisms controlling what molecules pass in and out of that core have been poorly understood. The newly characterized pore, assembled from viral proteins E8, E6, and L3, appears specifically shaped and charged to allow the export of RNA transcripts while physically and electrostatically excluding double-stranded DNA and cytosolic DNA-sensing proteins that would otherwise trigger host immune responses. This selective permeability suggests the portal complex plays a dual role: enabling viral replication by releasing early transcripts and shielding viral DNA from immune detection. The findings establish a structural basis for understanding poxvirus core assembly and function, and the identified proteins represent potential targets for antiviral drug development.
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- bioRxivCenter
Architecture of a portal complex embedded in the poxvirus core
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