Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1989 Aug;86(16):6121-5.
doi: 10.1073/pnas.86.16.6121.

Template supercoiling during ATP-dependent DNA helix tracking: studies with simian virus 40 large tumor antigen

Affiliations

Template supercoiling during ATP-dependent DNA helix tracking: studies with simian virus 40 large tumor antigen

L Yang et al. Proc Natl Acad Sci U S A. 1989 Aug.

Abstract

Incubation of topologically relaxed plasmid DNA with simian virus 40 (SV40) large tumor antigen (T antigen), ATP, and eubacterial DNA topoisomerase I resulted in the formation of highly positively supercoiled DNA. Eukaryotic DNA topoisomerase I could not substitute for eubacterial DNA topoisomerase 1 in this reaction. Furthermore, the addition of eukaryotic topoisomerase I to a preincubated reaction mixture containing both T antigen and eubacterial topoisomerase I caused rapid relaxation of the positively supercoiled DNA. These results suggest that SV40 T antigen can introduce topoisomerase-relaxable supercoils into DNA in a reaction coupled to ATP hydrolysis. We interpret the observed T antigen supercoiling reaction in terms of a recently proposed twin-supercoiled-domain model that describes the mechanics of DNA helix-tracking processes. According to this model positive and negative supercoils are generated ahead of and behind the moving SV40 T antigen, respectively. The preferential relaxation of negative supercoils by eubacterial DNA topoisomerase I explains the accumulation of positive supercoils in the DNA template. The supercoiling assay using DNA conformation-specific eubacterial DNA topoisomerase I may be of general use for the detection of ATP-dependent DNA helix-tracking proteins.

PubMed Disclaimer

Similar articles

Cited by

References

    1. Cell. 1978 Nov;15(3):979-84 - PubMed
    1. Cell. 1989 Jan 13;56(1):111-8 - PubMed
    1. Cell. 1980 Nov;22(2 Pt 2):447-57 - PubMed
    1. Cell. 1981 Jun;24(3):661-8 - PubMed
    1. Proc Natl Acad Sci U S A. 1981 Jun;78(6):3487-91 - PubMed

Publication types

MeSH terms