TY - JOUR
T1 - Assemblages of simian virus 40 capsid proteins and viral DNA visualized by electron microscopy
AU - Roitman-Shemer, Vered
AU - Stokrova, Jitka
AU - Forstova, Jitka
AU - Oppenheim, Ariella
PY - 2007/2/9
Y1 - 2007/2/9
N2 - SV40 assembles in the nucleus by addition of capsid proteins to the minichromosome. The VP15VP2/3 capsomer is composed of a pentamer of the major protein VP1 complexed with a monomer of a minor protein, VP2 or VP3. In the capsid, the capsomers are bound together via their flexible carboxy-terminal arms. Our previous studies suggested that the capsomers are recruited to the packaging signal ses via avid interaction with Sp1. During assembly Sp1 is displaced, allowing chromatin compaction. Here we investigated the interactions in vitro of VP15VP2/3 capsomers with the entire SV40 genome, using mutant VP1 deleted in the carboxy-arm that cannot assemble, but retains DNA-binding capacity. EM revealed that VP15VP2/3 complexes bind non-specifically at random locations around the DNA. Sp1 was absent from mature virions. The findings suggest that multiple capsomers attach simultaneously to the viral genome, increasing their local concentration, facilitating rapid, concerted assembly reaction and removal of Sp1.
AB - SV40 assembles in the nucleus by addition of capsid proteins to the minichromosome. The VP15VP2/3 capsomer is composed of a pentamer of the major protein VP1 complexed with a monomer of a minor protein, VP2 or VP3. In the capsid, the capsomers are bound together via their flexible carboxy-terminal arms. Our previous studies suggested that the capsomers are recruited to the packaging signal ses via avid interaction with Sp1. During assembly Sp1 is displaced, allowing chromatin compaction. Here we investigated the interactions in vitro of VP15VP2/3 capsomers with the entire SV40 genome, using mutant VP1 deleted in the carboxy-arm that cannot assemble, but retains DNA-binding capacity. EM revealed that VP15VP2/3 complexes bind non-specifically at random locations around the DNA. Sp1 was absent from mature virions. The findings suggest that multiple capsomers attach simultaneously to the viral genome, increasing their local concentration, facilitating rapid, concerted assembly reaction and removal of Sp1.
KW - Capsid proteins
KW - DNA spreads
KW - Electron microscopy
KW - Protein-DNA interactions
KW - SV40
UR - http://www.scopus.com/inward/record.url?scp=33845764903&partnerID=8YFLogxK
U2 - 10.1016/j.bbrc.2006.12.038
DO - 10.1016/j.bbrc.2006.12.038
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C2 - 17189615
AN - SCOPUS:33845764903
SN - 0006-291X
VL - 353
SP - 424
EP - 430
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -