This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chen, L.
Right arrow Articles by Simmons, D. T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chen, L.
Right arrow Articles by Simmons, D. T.

 Previous Article  |  Next Article 

J. Virol., Nov 1997, 8743-8749, Vol 71, No. 11
Copyright © 1997, American Society for Microbiology

The N-terminal side of the origin-binding domain of simian virus 40 large T antigen is involved in A/T untwisting

L Chen, WS Joo, PA Bullock and DT Simmons
Department of Biological Sciences, University of Delaware, Newark 19716, USA.

We investigated the role of the N-terminal side of simian virus 40 (SV40) large T antigen's origin-binding domain in the initiation of virus DNA replication by analyzing the biochemical activities of mutants containing single point substitutions or deletions in this region. Four mutants with substitutions at residues between 121 and 135 were partially defective in untwisting the A/T-rich track on the late side of the origin but were normal in melting the imperfect palindrome (IP) region on the early side. Deletion of the N-terminal 109 amino acids had no effect on either activity, whereas a longer deletion, up to residue 123, greatly reduced A/T untwisting but not IP melting. These results indicate that the region from residue 121 to 135 is important for A/T untwisting but not for IP melting and demonstrate that these activities are separable. Two point substitution mutants (126PS and 135PL) were characterized further by testing them for origin DNA binding, origin unwinding, oligomerization, and helicase activity. These two mutants were completely defective in origin (form U(R)) unwinding but normal in the other activities. Our results demonstrate that a failure to normally untwist the A/T track is correlated with a defect in origin unwinding. Further, they indicate that some mutants with substitutions in the region from residue 121 to 135 interact with origin DNA incorrectly, perhaps by failing to make appropriate contacts with the A/T-rich DNA.


This article has been cited by other articles:

  • Wang, W., Simmons, D. T. (2009). Simian Virus 40 Large T Antigen Can Specifically Unwind the Central Palindrome at the Origin of DNA Replication. J. Virol. 83: 3312-3322 [Abstract] [Full Text]  
  • Khopde, S., Simmons, D. T. (2008). Simian Virus 40 DNA Replication Is Dependent on an Interaction between Topoisomerase I and the C-Terminal End of T Antigen. J. Virol. 82: 1136-1145 [Abstract] [Full Text]  
  • Wang, W., Manna, D., Simmons, D. T. (2007). Role of the Hydrophilic Channels of Simian Virus 40 T-Antigen Helicase in DNA Replication. J. Virol. 81: 4510-4519 [Abstract] [Full Text]  
  • Sclafani, Robert. A., Fletcher, R. J., Chen, X. S. (2004). Two heads are better than one: regulation of DNA replication by hexameric helicases. Genes Dev. 18: 2039-2045 [Full Text]  
  • Jiao, J., Simmons, D. T. (2003). Nonspecific Double-Stranded DNA Binding Activity of Simian Virus 40 Large T Antigen Is Involved in Melting and Unwinding of the Origin. J. Virol. 77: 12720-12728 [Abstract] [Full Text]  
  • Kim, R. J., Moine, S., Reese, D. K., Bullock, P. A. (2002). Peptides Containing Cyclin/Cdk-Nuclear Localization Signal Motifs Derived from Viral Initiator Proteins Bind to DNA When Unphosphorylated. J. Virol. 76: 11785-11792 [Abstract] [Full Text]  
  • Uhlmann-Schiffler, H., Seinsoth, S., Stahl, H. (2002). Preformed hexamers of SV40 T antigen are active in RNA and origin-DNA unwinding. Nucleic Acids Res 30: 3192-3201 [Abstract] [Full Text]  
  • Sreekumar, K. R., Prack, A. E., Winters, D. R., Barbaro, B. A., Bullock, P. A. (2000). The Simian Virus 40 Core Origin Contains Two Separate Sequence Modules That Support T-Antigen Double-Hexamer Assembly. J. Virol. 74: 8589-8600 [Abstract] [Full Text]  
  • Barbaro, B. A., Sreekumar, K. R., Winters, D. R., Prack, A. E., Bullock, P. A. (2000). Phosphorylation of Simian Virus 40 T Antigen on Thr 124 Selectively Promotes Double-Hexamer Formation on Subfragments of the Viral Core Origin. J. Virol. 74: 8601-8613 [Abstract] [Full Text]  
  • Weisshart, K., Taneja, P., Jenne, A., Herbig, U., Simmons, D. T., Fanning, E. (1999). Two Regions of Simian Virus 40 T Antigen Determine Cooperativity of Double-Hexamer Assembly on the Viral Origin of DNA Replication and Promote Hexamer Interactions during Bidirectional Origin DNA Unwinding. J. Virol. 73: 2201-2211 [Abstract] [Full Text]  
  • Simmons, D. T., Roy, R., Chen, L., Gai, D., Trowbridge, P. W. (1998). The Activity of Topoisomerase I Is Modulated by Large T Antigen during Unwinding of the SV40 Origin. J. Biol. Chem. 273: 20390-20396 [Abstract] [Full Text]  
  • Joo, W. S., Kim, H. Y., Purviance, J. D., Sreekumar, K. R., Bullock, P. A. (1998). Assembly of T-Antigen Double Hexamers on the Simian Virus 40 Core Origin Requires Only a Subset of the Available Binding Sites. Mol. Cell. Biol. 18: 2677-2687 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»