• Register
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.


Leaving Community

Are you sure you want to leave this community? Leaving the community will revoke any permissions you have been granted in this community.


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

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.

Pubmed ID: 17525339


  • Elf J
  • Li GW
  • Xie XS


Science (New York, N.Y.)

Publication Data

May 25, 2007

Associated Grants

  • Agency: NIH HHS, Id: DP1 OD000277
  • Agency: NIH HHS, Id: DP1 OD000277-02

Mesh Terms

  • Bacterial Proteins
  • DNA, Bacterial
  • Diffusion
  • Escherichia coli
  • Escherichia coli Proteins
  • Kinetics
  • Lac Operon
  • Lac Repressors
  • Luminescent Proteins
  • Microscopy, Fluorescence
  • Operator Regions, Genetic
  • Protein Binding
  • Repressor Proteins
  • Signal Transduction