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

J Virol. 1996 Jun;70(6):3509-16. doi: 10.1128/JVI.70.6.3509-3516.1996.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Antigens, Polyomavirus Transforming / metabolism*
  • DNA Helicases / metabolism
  • DNA Polymerase II / metabolism*
  • DNA Replication*
  • DNA, Viral / metabolism*
  • Mutation
  • Simian virus 40 / immunology*
  • Simian virus 40 / physiology
  • Virus Replication*


  • Antigens, Polyomavirus Transforming
  • DNA, Viral
  • DNA Polymerase II
  • Adenosine Triphosphatases
  • DNA Helicases