Assembly of the Ebola Virus Nucleoprotein from a Chaperoned VP35 Complex

• An N-terminal portion of Ebola virus VP35 chaperones the viral nucleoprotein NP
• The structure of Ebola NP is solved to 2.4 Å in the form of this NP°-VP35 complex
• VP35 chaperones monomeric NP via conserved, high-affinity hydrophobic interactions
• Oligomerization-induced conformational changes in NP form its RNA binding site

SummaryEbolavirus NP oligomerizes into helical filaments found at the core of the virion, encapsidates the viral RNA genome, and serves as a scaffold for additional viral proteins within the viral nucleocapsid. We identified a portion of the phosphoprotein homolog VP35 that binds with high affinity to nascent NP and regulates NP assembly and viral genome binding. Removal of the VP35 peptide leads to NP self-assembly via its N-terminal oligomerization arm. NP oligomerization likely causes a conformational change between the NP N- and C-terminal domains, facilitating RNA binding. These functional data are complemented by crystal structures of the NP°-VP35 complex at 2.4 Å resolution. The interactions between NP and VP35 illuminated by these structures are conserved among filoviruses and provide key targets for therapeutic intervention.

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