Single-molecule studies of repressor-DNA interactions show long-range interactions.
We have performed single-molecule studies of GFP-LacI repressor proteins bound to bacteriophage lambda DNA containing a 256 tandem lac operator insertion confined in nanochannels. An integrated photon molecular counting method was developed to determine the number of proteins bound to DNA. By using this method, we determined the saturated mean occupancy of the 256 tandem lac operators to be 13, which constitutes only 2.5% of the available sites. This low occupancy level suggests that the repressors influence each other even when they are widely separated, at distances on the order of 200 nm, or several DNA persistence lengths.
Wang
Y M
YM
Departments of Physics, Molecular Biology, and Electrical Engineering, Princeton University, Princeton, NJ 08544.
Tegenfeldt
Jonas O
JO
Reisner
W
W
Riehn
R
R
Guan
Xiao-Juan
XJ
Guo
Ling
L
Golding
Ido
I
Cox
Edward C
EC
Sturm
James
J
Austin
Robert H
RH
D010582:Bacteriophage lambda / Q000235:genetics*; D055592:Biophysical Phenomena; D001703:Biophysics; D002232:Carbocyanines; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification*; D004586:Electrophoresis / Q000379:methods; D049452:Green Fluorescent Proteins / Q000378:metabolism; D036103:Nanotechnology / Q000379:methods; D009875:Operator Regions, Genetic / Q000235:genetics*; D012097:Repressor Proteins / Q000378:metabolism*
C098829:BOBO 3; D002232:Carbocyanines; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D049452:Green Fluorescent Proteins