A protein with simultaneous capsid scaffolding and dsRNA-binding activities enhances the birnavirus capsid mechanical stability.
Viral capsids are metastable structures that perform many essential processes; they also act as robust cages during the extracellular phase. Viruses can use multifunctional proteins to optimize resources (e.g., VP3 in avian infectious bursal disease virus, IBDV). The IBDV genome is organized as ribonucleoproteins (RNP) of dsRNA with VP3, which also acts as a scaffold during capsid assembly. We characterized mechanical properties of IBDV populations with different RNP content (ranging from none to four RNP). The IBDV population with the greatest RNP number (and best fitness) showed greatest capsid rigidity. When bound to dsRNA, VP3 reinforces virus stiffness. These contacts involve interactions with capsid structural subunits that differ from the initial interactions during capsid assembly. Our results suggest that RNP dimers are the basic stabilization units of the virion, provide better understanding of multifunctional proteins, and highlight the duality of RNP as capsid-stabilizing and genetic information platforms.
Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) Campus Cantoblanco, 28049 Madrid, Spain.|Unidad Asociada de Nanobiotecnología CNB-CSIC-IMDEA, Cantoblanco, E-28049 Madrid, Spain.
Johann
J
Mertens
Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) Campus Cantoblanco, 28049 Madrid, Spain.
Santiago
S
Casado
Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Campus Cantoblanco, 28049 Madrid, Spain.
Carlos P
CP
Mata
Departamento de Física de la Materia Condensada C03, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Mercedes
M
Hernando-Pérez
Departamento de Física de la Materia Condensada C03, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Pedro J
PJ
de Pablo
Unidad Asociada de Nanobiotecnología CNB-CSIC-IMDEA, Cantoblanco, E-28049 Madrid, Spain.|Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Campus Cantoblanco, 28049 Madrid, Spain.
José L
JL
Carrascosa
Unidad Asociada de Nanobiotecnología CNB-CSIC-IMDEA, Cantoblanco, E-28049 Madrid, Spain.|Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Campus Cantoblanco, 28049 Madrid, Spain.
José R
JR
Castón
D001665:Binding Sites; D018059:Birnaviridae / Q000737:chemistry* / Q000502:physiology*; D002213:Capsid / Q000737:chemistry* / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology; D011485:Protein Binding; D012367:RNA, Viral / Q000737:chemistry* / Q000502:physiology*; D012261:Ribonucleoproteins; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology
D012367:RNA, Viral; D012261:Ribonucleoproteins