title: Simian virus 40 VP1 capsid protein forms polymorphic assemblies in vitro.
abstract: The simian virus 40 (SV40) capsid is composed of 72 pentamers of VP1, the major protein of SV40. These pentamers are arranged in a T=7d icosahedral surface lattice, which is maintained by three types of appropriately arranged, non-equivalent interactions between the pentamers. However, it remains unclear how these interactions are achieved. In this study, the in vitro assembly of recombinant VP1 was analysed. Electron microscopy observations revealed that these recombinant VP1 proteins assembled into structurally polymorphic particles depending on environmental conditions. VP1 pentamers assembled efficiently into virus-like particles (VLPs) when high concentrations of ammonium sulfate were present. However, in the presence of 1 M NaCl and 2 mM CaCl(2) at neutral pH, VP1 pentamers formed not only VLPs but also produced tiny T=1 icosahedral particles and tubular structures. The exclusion of CaCl(2) resulted in the exclusive formation of tiny particles. In contrast, in the presence of 150 mM NaCl at pH 5, the VP1 pentamers produced only extraordinarily long tubular structures. VP1 is thus quite unique in that it can assemble into such diverse structures. These observations provide clues that will help elucidate the mechanisms underlying SV40 capsid formation.
authors.affiliation: Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Shin-Nosuke
authors.initials: SN
authors.lastname: Kanesashi
authors.affiliation: Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Ken-Ichiro
authors.initials: KI
authors.lastname: Ishizu
authors.affiliation: Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Masa-Aki
authors.initials: MA
authors.lastname: Kawano
authors.affiliation: Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Song-Iee
authors.initials: SI
authors.lastname: Han
authors.affiliation: Radioisotope Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Tomita
authors.affiliation: Center for Integrative Bioscience, Okazaki National Research Institutes, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kataoka
authors.affiliation: Faculty of Bioscience and Biotechnology and Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Handa
mesh_terms: D000818:Animals; D002021:Buffers; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003956:Dialysis; D008854:Microscopy, Electron; D011994:Recombinant Proteins / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018411:Spodoptera; D014771:Virion / Q000378:metabolism / Q000648:ultrastructure*; D019065:Virus Assembly
chemical_list: D002021:Buffers; D036022:Capsid Proteins; D011994:Recombinant Proteins