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Probing transcription factor dynamics at the single-molecule level in a living cell.

ABSTRACT: Transcription factors regulate gene expression through their binding to DNA. In a living Escherichia coli cell, we directly observed specific binding of a lac repressor, labeled with a fluorescent protein, to a chromosomal lac operator. Using single-molecule detection techniques, we measured the kinetics of binding and dissociation of the repressor in response to metabolic signals. Furthermore, we characterized the nonspecific binding to DNA, one-dimensional (1D) diffusion along DNA segments, and 3D translocation among segments through cytoplasm at the single-molecule level. In searching for the operator, a lac repressor spends approximately 90% of time nonspecifically bound to and diffusing along DNA with a residence time of <5 milliseconds. The methods and findings can be generalized to other nucleic acid binding proteins.

SUBMITTER: Elf J

PROVIDER: S-EPMC2853898 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature

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Probing transcription factor dynamics at the single-molecule level in a living cell.

Elf Johan J Li Gene-Wei GW Xie X Sunney XS

Science (New York, N.Y.) 20070501 5828

Transcription factors regulate gene expression through their binding to DNA. In a living Escherichia coli cell, we directly observed specific binding of a lac repressor, labeled with a fluorescent protein, to a chromosomal lac operator. Using single-molecule detection techniques, we measured the kinetics of binding and dissociation of the repressor in response to metabolic signals. Furthermore, we characterized the nonspecific binding to DNA, one-dimensional (1D) diffusion along DNA segments, an ...[more]

PMID: 17525339

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