期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：3
页码：718-722
DOI：10.1073/pnas.88.3.718
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Transcription of the fibroin gene can be reconstituted with partially purified components from HeLa cells. Transcription factors IIB, IID, and IIE and RNA polymerase II are required for accurate initiation of transcription. Linear and relaxed closed circular DNA show a similar level of template activity. However, transcription of closed circular DNA is stimulated when negative supercoils are introduced by the addition of DNA topoisomerase II and supercoiling factor purified from the posterior silk gland of Bombyx mori. Dissection of transcription into pre- and postinitiation steps by the use of Sarkosyl reveals that DNA supercoiling promotes formation of a preinitiation complex. Furthermore, order of addition experiments suggest that DNA supercoiling facilitates a functional binding of transcription factor IID to the promoter.
