Structural Insights into the Multifunctional Protein VP3 of Birnaviruses

Infectious bursal disease virus (IBDV), a member of the Birnaviridae family, is the causative agent of one of the most harmful poultry diseases. The IBDV genome encodes five mature proteins; of these, the multifunctional protein VP3 plays an essential role in virus morphogenesis. This protein, which interacts with the structural protein VP2, with the double-stranded RNA genome, and with the virus-encoded, RNA-dependent RNA polymerase, VP1, is involved not only in the formation of the viral capsid, but also in the recruitment of VP1 into the capsid and in the encapsidation of the viral genome. Here, we report the X-ray structure of the central region of VP3, residues 92-220, consisting of two α-helical domains connected by a long and flexible hinge that are organized as a dimer. Unexpectedly, the overall fold of the second VP3 domain shows significant structural similarities with different transcription regulation factors. © 2008 Elsevier Ltd. All rights reserved.This work was supported by grants AGL2003-07189/BIO2006-09407 and BFU2005-02376/BMC from The Ministerio de Educacion y Ciencia to J.F.R. and to N.V., respectively. A.C. was supported by an I3P fellowship from Consejo Superior de Investigaciones Cientificas (CSIC)-Ministerio de Educación y Ciencia, and C.F.-O. was supported by a Proyecto Intramural de Frontera fellowship from CSICPeer Reviewe