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

L. Yang, C. B. Jessee, K. Lau, H. Zhang, L. F. Liu

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33 引文 斯高帕斯(Scopus)

摘要

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 I 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.

原文英語
頁(從 - 到)6121-6125
頁數5
期刊Proceedings of the National Academy of Sciences of the United States of America
86
發行號16
DOIs
出版狀態已發佈 - 1989
對外發佈

ASJC Scopus subject areas

  • 多學科

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