The VP2/VP3 Minor Capsid Protein of Simian Virus 40 Promotes the in Vitro Assembly of the Major Capsid Protein VP1 into Particles

The SV40 capsid is composed primarily of 72 pentamers of the VP1 major capsid protein. Although the capsid also contains the minor capsid protein VP2 and its amino-terminally truncated form VP3, their roles in capsid assembly remain unknown. An in vitro assembly system was used to investigate the ro...

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Bibliographic Details
Published in:The Journal of biological chemistry 2006-04, Vol.281 (15), p.10164-10173
Main Authors: Kawano, Masa-aki, Inoue, Takamasa, Tsukamoto, Hiroko, Takaya, Tatsuya, Enomoto, Teruya, Takahashi, Ryou-u, Yokoyama, Naoki, Yamamoto, Noriaki, Nakanishi, Akira, Imai, Takeshi, Wada, Tadashi, Kataoka, Kohsuke, Handa, Hiroshi
Format: Article
Language:English
Subjects:
Animals
Capsid - chemistry
Capsid Proteins - chemistry
Capsid Proteins - metabolism
Capsid Proteins - physiology
Centrifugation, Density Gradient
Electrophoresis, Polyacrylamide Gel
Glycine - chemistry
Hydrogen-Ion Concentration
Insecta
Microscopy, Electron
Plasmids - metabolism
Protein Binding
Protein Conformation
Protein Structure, Tertiary
Simian virus 40
Simian virus 40 - metabolism
Solvents - chemistry
Sucrose - pharmacology
Virus Assembly
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Summary:The SV40 capsid is composed primarily of 72 pentamers of the VP1 major capsid protein. Although the capsid also contains the minor capsid protein VP2 and its amino-terminally truncated form VP3, their roles in capsid assembly remain unknown. An in vitro assembly system was used to investigate the role of VP2 in the assembly of recombinant VP1 pentamers. Under physiological salt and pH conditions, VP1 alone remained dissociated, and at pH 5.0, it assembled into tubular structures. A stoichiometric amount of VP2 allowed the assembly of VP1 pentamers into spherical particles in a pH range of 7.0 to 4.0. Electron microscopy observation, sucrose gradient sedimentation analysis, and antibody accessibility tests showed that VP2 is incorporated into VP1 particles. The functional domains of VP2 important for VP1 binding and for enhancing VP1 assembly were further explored with a series of VP2 deletion mutants. VP3 also enhanced VP1 assembly, and a region common to VP2 and VP3 (amino acids 119-272) was required to promote VP1 pentamer assembly. These results are relevant for controlling recombinant capsid formation in vitro, which is potentially useful for the in vitro development of SV40 virus vectors.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M511261200