Single molecule measurements of repressor protein 1D diffusion on DNA

Y. M. Wang, Robert H. Austin, Edward C. Cox

Research output: Contribution to journalArticlepeer-review

286 Scopus citations


We used single-molecule imaging techniques and measured the one-dimensional diffusion of LacI repressor proteins along elongated DNA to address the long-standing puzzle of why some proteins find their targets faster than allowed by 3D diffusion. Our analysis of the LacI transcription factor's diffusion yielded four main results: (1) LacI diffuses along nonspecific sequences of DNA in the form of 1D Brownian motion; (2) the observed 1D diffusion coefficients D1 vary over an unexpectedly large range, from 2.3×10-12cm2/s to 1.3×10-9cm2/s; (3) the lengths of DNA covered by these 1D diffusions vary from 120 nm to 2920 nm; and (4) the mean values of D1 and the diffusional lengths indeed predict a LacI target binding rate 90 times faster than the 3D diffusion limit.

Original languageEnglish (US)
Article number048302
JournalPhysical review letters
Issue number4
StatePublished - 2006

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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