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 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.
Kawano
Masa-aki
MA
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan.
Inoue
Takamasa
T
Tsukamoto
Hiroko
H
Takaya
Tatsuya
T
Enomoto
Teruya
T
Takahashi
Ryou-u
RU
Yokoyama
Naoki
N
Yamamoto
Noriaki
N
Nakanishi
Akira
A
Imai
Takeshi
T
Wada
Tadashi
T
Kataoka
Kohsuke
K
Handa
Hiroshi
H
D000818:Animals; D002213:Capsid / Q000737:chemistry; D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D005998:Glycine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007313:Insecta; D008854:Microscopy, Electron; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013539:Simian virus 40 / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry; D013395:Sucrose / Q000494:pharmacology; D019065:Virus Assembly
D036022:Capsid Proteins; D012997:Solvents; C062481:VP1 protein, polyomavirus; C442543:VP2 protein, Polyomavirus; C085902:VP3 protein, Simian virus 40; D013395:Sucrose; D005998:Glycine