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DNA supercoiling enhances cooperativity and efficiency of an epigenetic switch.

ABSTRACT: Bacteriophage ? stably maintains its dormant prophage state but efficiently enters lytic development in response to DNA damage. The mediator of these processes is the ? repressor protein, CI, and its interactions with ? operator DNA. This ? 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 ? 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 ? switch is significantly increased in the supercoiled system compared with a linear assay, increasing the Hill coefficient.

SUBMITTER: Norregaard K

PROVIDER: S-EPMC3808602 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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DNA supercoiling enhances cooperativity and efficiency of an epigenetic switch.

Norregaard Kamilla K Andersson Magnus M Sneppen Kim K Nielsen Peter Eigil PE Brown Stanley S Oddershede Lene B LB

Proceedings of the National Academy of Sciences of the United States of America 20131007 43

Bacteriophage λ stably maintains its dormant prophage state but efficiently enters lytic development in response to DNA damage. The mediator of these processes is the λ repressor protein, CI, and its interactions with λ operator DNA. This λ 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 λ operat ...[more]

PMID: 24101469

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