标题：Enhancement of RNA polymerase binding to promoters by a transcriptional activator, OmpR, in Escherichia coli: its positive and negative effects on transcription.
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：1990
卷号：87
期号：15
页码：5940-5944
DOI：10.1073/pnas.87.15.5940
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The OmpR binding sequence (OBS) in the upstream region of the ompF promoter of Escherichia coli was fused to 27 synthetic promoters. Transcription from a number of weak promoters, regardless of their sequences, was dramatically activated in the presence of OmpR, a transcriptional activator. In vivo DNA footprinting revealed that OmpR enhanced the binding of RNA polymerase to the promoters. This enhancement was essential for transcription of weak promoters, while OmpR binding to the OBS fused to a strong promoter was inhibitory for transcription. These results indicate that OmpR stabilizes the formation of an RNA polymerase-promoter complex, possibly a closed promoter complex, and that a transcription activator can serve not only as a positive but also as a negative regulator for gene expression.
