One dimensional diffusion constant of LacI repressor dimer along DNA segments

Value 0.046 µm^2/sec Range: ±0.01 equivalent to (4.0±0.9)×10^5 bp^2/sec µm^2/sec
Organism Bacteria Escherichia coli
Reference Elf J, Li G, Xie XS. 2007. Probing transcription factor dynamics at the single-molecule level in a living cell. Science 316:1191–94 p.1193 table 1 & right column 2nd paragraphPubMed ID17525339
Method In vitro single-molecule tracking (of fusion lacI repressor-venus yellow fluorescent protein) on flow-stretched DNA
Comments "The conventional view is that the search is facilitated by a combination of 1D diffusion along short DNA segments separated by transfers between segments through cytoplasm. Recent in vitro experiments on DNA-repair enzymes have directly demonstrated the 1D diffusion along nonspecific DNA (ref 25). Similarly, [investigators] determined the 1D diffusion constant of the dimeric LacI-Venus to be D1 = 0.046 ± 0.01 µm^2/s using single-molecule tracking on flow-stretched DNA (SOM supporting online material)." This is equivalent to D1=(4.0±0.9)×10^5 bp^2/sec (Supporting Online Material pp 5). Note that the apparent diffusion coefficient is one order of magnitude higher, 0.4±0.02µm^2/sec (BNID 102038), as the Lac I dimer spends ~87% of the time nonspecifically bound and diffusing along DNA (D=0.046±0.01µm^2/sec) and the rest of the time unbound to DNA (D=3µm^2/sec).
Entered by Uri M
ID 102036