FC0039
Ebola virus nucleoprotein  -  virion protein 35 (VP35)

Biological function
The Ebola virus nucleoprotein (NP) is an essential component of the nucleocapsid, required for filovirus particle formation and replication. Together with virion protein 35 (VP35) and VP24, this gene product gives rise to the filamentous nucleocapsid within transfected cells.

Domain organization/sequence features
The COOH-terminal NP domain (439 to 739) comprises a conserved highly acidic region of NP with predicted disorder, distinguishing Ebola virus NPs from paramyxo-virus NPs. The acidic character of this filovirus unique domain is likely responsible for its aberrant biochemical properties.

Structural evidence
Ebola virus NP migrates aberrantly, with an apparent molecular mass of 115 kDa, although it is predicted to encode an approx. 85-kDa protein. This is mostly owing to two domains (439 to 492 and 589 to 739).

Biochemical evidence
The 439-492 and 589-739 regions, which determine this aberrant migration of Ebola NP also mediate its incorporation into virions. When the 438-739 region was appended to either measles NP or RSV NP, the fusion protein, in contrast to the parental NP, was able to bind VP35 by immunoprecipitation and Western blotting.

Mechanism category
competitive binding

Significance
Fuzziness of the filovirus-unique region of NP contributes to both the assembly and the morphology of this distinct class of viruses.