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：2013
卷号：110
期号：43
页码：17386-17391
DOI：10.1073/pnas.1215907110
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Bacteriophage {lambda} stably maintains its dormant prophage state but efficiently enters lytic development in response to DNA damage. The mediator of these processes is the {lambda} repressor protein, CI, and its interactions with {lambda} operator DNA. This {lambda} switch is a model on the basis of which epigenetic switch regulation is understood. Using single molecule analysis, we directly examined the stability of the CI-operator structure in its natural, supercoiled state. We marked positions adjacent to the {lambda} operators with peptide nucleic acids and monitored their movement by tethered particle tracking. Compared with relaxed DNA, the presence of supercoils greatly enhances juxtaposition probability. Also, the efficiency and cooperativity of the {lambda} switch is significantly increased in the supercoiled system compared with a linear assay, increasing the Hill coefficient.
