Name
Structural analysis of yadonushi/yadokari viruses in fungi Rosellinia necatrix and Aspergillus foetidus
Presenter
Jose Caston, CSIC
Co-Author(s)
José R. Castón (1), Guy Novoa (1) and Nobuhiro Suzuki (2)
(1) Department of Structure of Macromolecules, CNB-CSIC, Madrid, Spain. (2) Institute of Plant Science and Resources, University of Okayama, Okayama, Japan
Abstract Category
Structural Biology
Abstract
Many fungal hosts are infected simultaneously by dsRNA, (+) ssRNA, (-) ssRNA and ssDNA viruses. In the yadokari/yadonushi nature, a capsidless (+) ssRNA yadokarivirus hijacks the capsid of a partner dsRNA yadonushivirus to hetero-encapsidate its RNA and RdRp. Here, we analyzed two yadokari/yadonushi systems: the (+) ssRNA Yadokari virus 1 (YkV1) and the dsRNA Yadonushi virus 1 (YnV1) in Rosellinia necatrix, and the yadokarivirus Aspergillus foetidus slow virus 2 (AfSV2) with Aspergillus foetidus slow virus 1 (AfSV1) in Aspergillus foetidus.
The cryo-EM structures of YnV1/YkV1 and AfSV1/AfSV2 were determined at 2.2 Å resolution. The ~540 Å-diameter YnV1capsid has a 120-subunit T=1 icosahedral capsid, and the asymmetric unit is a 1023-aa CP homodimer (A and B subunits). Monomers A have of a long α-helix that reduces the diameter of the 5-fold axis channels. The packaged genome follows two organizations, either as three concentric layers of ~20 Å filaments with a single-spooled organization, or as noisy, irregular densities. The ~440 Å-diameter AfSV1 capsid has a T=1 lattice made of 120 741-aa CP molecules. The B subunit has an unstructured, long C-terminal end that establishes a network of interactions with numerous subunits. The AfSV1 genome organization is similar to that of YnV1. Structural superposition of the YnV1 and AfSV1 CPs with other dsRNA mycovirus CPs, including ScV L-A and PcV, highlighted a conserved motif formed by 8 α-helices and 2-3 β-strands, and ‘hot spots’, in which structural and functional variations are introduced by the insertion of distinct segments.
The cryo-EM structures of YnV1/YkV1 and AfSV1/AfSV2 were determined at 2.2 Å resolution. The ~540 Å-diameter YnV1capsid has a 120-subunit T=1 icosahedral capsid, and the asymmetric unit is a 1023-aa CP homodimer (A and B subunits). Monomers A have of a long α-helix that reduces the diameter of the 5-fold axis channels. The packaged genome follows two organizations, either as three concentric layers of ~20 Å filaments with a single-spooled organization, or as noisy, irregular densities. The ~440 Å-diameter AfSV1 capsid has a T=1 lattice made of 120 741-aa CP molecules. The B subunit has an unstructured, long C-terminal end that establishes a network of interactions with numerous subunits. The AfSV1 genome organization is similar to that of YnV1. Structural superposition of the YnV1 and AfSV1 CPs with other dsRNA mycovirus CPs, including ScV L-A and PcV, highlighted a conserved motif formed by 8 α-helices and 2-3 β-strands, and ‘hot spots’, in which structural and functional variations are introduced by the insertion of distinct segments.