Single molecule measurements of repressor protein 1D diffusion on DNA.
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 D1vary over an unexpectedly large range, from 2.3x10(-12) cm2/s to 1.3x10(-9) cm2/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.
Wang
Y M
YM
Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Austin
Robert H
RH
Cox
Edward C
EC
D001426:Bacterial Proteins / Q000032:analysis / Q000737:chemistry*; D001665:Binding Sites; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000032:analysis / Q000737:chemistry*; D004058:Diffusion; D056968:Lac Repressors; D008956:Models, Chemical; D008958:Models, Molecular; D009038:Motion; D011485:Protein Binding; D012097:Repressor Proteins / Q000032:analysis / Q000737:chemistry*; D013314:Stress, Mechanical
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D056968:Lac Repressors; D012097:Repressor Proteins; D004247:DNA