2r18
From Proteopedia
Structural insights into the multifunctional protein VP3 of Birnaviruses
Structural highlights
Function[POLS_IBDVP] Capsid protein VP2 self assembles to form an icosahedral capsid with a T=13 symmetry, about 70 nm in diameter, and consisting of 260 VP2 trimers. The capsid encapsulates the genomic dsRNA. VP2 is also involved in attachment and entry into the host cell by interacting with host ITGA4/ITGB1 (By similarity). The precursor of VP2 plays an important role in capsid assembly. First, pre-VP2 and VP2 oligomers assemble to form a procapsid. Then, the pre-VP2 intermediates may be processed into VP2 proteins by proteolytic cleavage mediated by VP4 to obtain the mature virion. The final capsid is composed of pentamers and hexamers but VP2 has a natural tendency to assemble into all-pentameric structures. Therefore pre-VP2 may be required to allow formation of the hexameric structures (By similarity). Protease VP4 is a serine protease that cleaves the polyprotein into its final products. Pre-VP2 is first partially cleaved, and may be completely processed by VP4 upon capsid maturation (By similarity). Capsid protein VP3 plays a key role in virion assembly by providing a scaffold for the capsid made of VP2. May self-assemble to form a T=4-like icosahedral inner-capsid composed of at least 180 trimers. Plays a role in genomic RNA packaging by recruiting VP1 into the capsid and interacting with the dsRNA genome segments to form a ribonucleoprotein complex. Additionally, the interaction of the VP3 C-terminal tail with VP1 removes the inherent structural blockade of the polymerase active site. Thus, VP3 can also function as a transcriptional activator (By similarity). Structural peptide 1 is a small peptide derived from pre-VP2 C-terminus. It destabilizes and perforates cell membranes, suggesting a role during entry (By similarity). Structural peptide 2 is a small peptide derived from pVP2 C-terminus. It is not essential for the virus viability, but viral growth is affected when missing (By similarity). Structural peptide 3 is a small peptide derived from pVP2 C-terminus. It is not essential for the virus viability, but viral growth is affected when missing (By similarity). Structural peptide 4 is a small peptide derived from pVP2 C-terminus. It is essential for the virus viability (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedInfectious 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 alpha-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. Structural insights into the multifunctional protein VP3 of birnaviruses.,Casanas A, Navarro A, Ferrer-Orta C, Gonzalez D, Rodriguez JF, Verdaguer N Structure. 2008 Jan;16(1):29-37. PMID:18184581[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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