title: Mutational analysis of the carboxyl-terminal region of the SV40 major capsid protein VP1.
abstract: Virus-like particles (VLPs), a promising next-generation drug delivery vehicle, can be formed in vitro using a recombinant viral capsid protein VP1 from SV40. Seventy-two VP1 pentamers interconnect to form the T = 7d lattice of SV40 capsids, through three types of C-terminal interactions, alpha-alpha'-alpha'', beta-beta' and gamma-gamma. These appear to require VP1 conformational switch, which involve in particular the region from amino acids 301-312 (herein Region I). Here we show that progressive deletions from the C-terminus of VP1, up to 34 amino acids, cause size and shape variations in the resulting VLPs, including tubular formation, whereas deletions beyond 34 amino acids simply blocked VP1 self-assembly. Mutants carrying in Region I point mutations predicted to disrupt alpha-alpha'-alpha''-type and/or beta-beta'-type interactions formed small VLPs resembling T = 1 symmetry. Chimeric VP1, in which Region I of SV40 VP1 was substituted with the homologous region from VP1 of other polyomaviruses, assembled only into small VLPs. Together, our results show the importance of the integrity of VP1 C-terminal region and the specific amino acid sequences within Region I in the assembly of normal VLPs. By understanding how to alter VLP sizes and shapes contributes to the development of drug delivery systems using VLPs.
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Masa-aki
authors.initials: MA
authors.lastname: Kawano
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tsukamoto
authors.forename: Teruya
authors.initials: T
authors.lastname: Enomoto
authors.forename: Takamasa
authors.initials: T
authors.lastname: Inoue
authors.forename: Ryou-u
authors.initials: RU
authors.lastname: Takahashi
authors.forename: Akira
authors.initials: A
authors.lastname: Nakanishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imai
authors.forename: Tadashi
authors.initials: T
authors.lastname: Wada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Handa
mesh_terms: D000818:Animals; D002213:Capsid / Q000378:metabolism; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics*; D002460:Cell Line; D016503:Drug Delivery Systems / Q000379:methods; D008958:Models, Molecular; D009154:Mutation; D011120:Polyomavirus / Q000737:chemistry / Q000235:genetics; D013539:Simian virus 40 / Q000737:chemistry*; D018411:Spodoptera / Q000166:cytology
chemical_list: D036022:Capsid Proteins; C062481:VP1 protein, polyomavirus