Probing Transcription Factor Dynamics at the Single Molecule Level in a Living Cell

by Johan Elf (Cell & Molecular Biology, Uppsala University)

Tuesday 16 Oct 2007, 15:00 → 16:00 Europe/Stockholm

Roslagstullsbacken 35

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 intracellular translocation display normal diffusion at a >10ms time scale.

Reference:

Elf, Li and Xie (2007). Probing Transcription Factor Dynamics at the Single Molecule Level a Living Cell, Science <bf>316</bf> 1191-4