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-Structure paper
タイトル | Infectious bursal disease virus capsid assembly and maturation by structural rearrangements of a transient molecular switch. |
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ジャーナル・号・ページ | J Virol, Vol. 81, Issue 13, Page 6869-6878, Year 2007 |
掲載日 | 2007年4月18日 |
著者 | Daniel Luque / Irene Saugar / José F Rodríguez / Nuria Verdaguer / Damiá Garriga / Carmen San Martín / Javier A Velázquez-Muriel / Benes L Trus / José L Carrascosa / José R Castón / |
PubMed 要旨 | Infectious bursal disease virus (IBDV), a double-stranded RNA (dsRNA) virus belonging to the Birnaviridae family, is an economically important avian pathogen. The IBDV capsid is based on a single- ...Infectious bursal disease virus (IBDV), a double-stranded RNA (dsRNA) virus belonging to the Birnaviridae family, is an economically important avian pathogen. The IBDV capsid is based on a single-shelled T=13 lattice, and the only structural subunits are VP2 trimers. During capsid assembly, VP2 is synthesized as a protein precursor, called pVP2, whose 71-residue C-terminal end is proteolytically processed. The conformational flexibility of pVP2 is due to an amphipathic alpha-helix located at its C-terminal end. VP3, the other IBDV major structural protein that accomplishes numerous roles during the viral cycle, acts as a scaffolding protein required for assembly control. Here we address the molecular mechanism that defines the multimeric state of the capsid protein as hexamers or pentamers. We used a combination of three-dimensional cryo-electron microscopy maps at or close to subnanometer resolution with atomic models. Our studies suggest that the key polypeptide element, the C-terminal amphipathic alpha-helix, which acts as a transient conformational switch, is bound to the flexible VP2 C-terminal end. In addition, capsid protein oligomerization is also controlled by the progressive trimming of its C-terminal domain. The coordination of these molecular events correlates viral capsid assembly with different conformations of the amphipathic alpha-helix in the precursor capsid, as a five-alpha-helix bundle at the pentamers or an open star-like conformation at the hexamers. These results, reminiscent of the assembly pathway of positive single-stranded RNA viruses, such as nodavirus and tetravirus, add new insights into the evolutionary relationships of dsRNA viruses. |
リンク | J Virol / PubMed:17442720 / PubMed Central |
手法 | EM (単粒子) |
解像度 | 7.2 - 14.0 Å |
構造データ | EMDB-1237: EMDB-1238: EMDB-1239: |