ジャーナル: Nat Struct Mol Biol / 年: 2010 タイトル: Structural changes in a marine podovirus associated with release of its genome into Prochlorococcus. 著者: Xiangan Liu / Qinfen Zhang / Kazuyoshi Murata / Matthew L Baker / Matthew B Sullivan / Caroline Fu / Matthew T Dougherty / Michael F Schmid / Marcia S Osburne / Sallie W Chisholm / Wah Chiu / 要旨: Podovirus P-SSP7 infects Prochlorococcus marinus, the most abundant oceanic photosynthetic microorganism. Single-particle cryo-electron microscopy yields icosahedral and asymmetrical structures of ...Podovirus P-SSP7 infects Prochlorococcus marinus, the most abundant oceanic photosynthetic microorganism. Single-particle cryo-electron microscopy yields icosahedral and asymmetrical structures of infectious P-SSP7 with 4.6-A and 9-A resolution, respectively. The asymmetric reconstruction reveals how symmetry mismatches are accommodated among five of the gene products at the portal vertex. Reconstructions of infectious and empty particles show a conformational change of the 'valve' density in the nozzle, an orientation difference in the tail fibers, a disordering of the C terminus of the portal protein and the disappearance of the core proteins. In addition, cryo-electron tomography of P-SSP7 infecting Prochlorococcus showed the same tail-fiber conformation as that in empty particles. Our observations suggest a mechanism whereby, upon binding to the host cell, the tail fibers induce a cascade of structural alterations of the portal vertex complex that triggers DNA release.