An N-terminal deletion mutant of simian virus 40 (SV40) large T antigen oligomerizes incorrectly on SV40 DNA but retains the ability to bind to DNA polymerase alpha and replicate SV40 DNA in vitro.
A peptide encompassing the N-terminal 82 amino acids of simian virus 40 (SV40) large T antigen was previously shown to bind to the large subunit of DNA polymerase alpha-primase (I. Dornreiter, A. Höss, A. K. Arthur, and E. Fanning, EMBO J. 9:3329-3336, 1990). We report here that a mutant T antigen, T83-708, lacking residues 2 to 82 retained the ability to bind to DNA polymerase alpha-primase, implying that it carries a second binding site for DNA polymerase alpha-primase. The mutant protein also retained ATPase, helicase, and SV40 origin DNA-binding activity. However, its SV40 DNA replication activity in vitro was reduced compared with that of wild-type protein. The reduction in replication activity was accompanied by a lower DNA-binding affinity to SV40 origin sequences and aberrant oligomerization on viral origin DNA. Thus, the first 82 residues of SV40 T antigen are not strictly required for its interaction with DNA polymerase alpha-primase or for DNA replication function but may play a role in correct hexamer assembly and efficient DNA binding at the origin.
Weisshart
K
K
Institute for Biochemistry, Munich, Germany.
Bradley
M K
MK
Weiner
B M
BM
Schneider
C
C
Moarefi
I
I
Fanning
E
E
Arthur
A K
AK
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism*; D004261:DNA Replication; D004279:DNA, Viral / Q000378:metabolism*; D009154:Mutation; D013539:Simian virus 40 / Q000276:immunology* / Q000502:physiology; D014779:Virus Replication
D000952:Antigens, Polyomavirus Transforming; D004279:DNA, Viral; D004257:DNA Polymerase II; D000251:Adenosine Triphosphatases; D004265:DNA Helicases