Electrophoretic force on a protein-coated DNA molecule in a solid-state nanopore.
Using solid-state nanopores with optical tweezers, we perform force spectroscopy on DNA molecules that are coated with RecA proteins. We observe that the electrophoretic force is 2-4 times larger for RecA-DNA filaments than for uncoated DNA molecules and that this force increases at lower salt concentrations. The data demonstrate the efficacy of solid-state nanopores for locally probing the forces on DNA-bound proteins. Our results are described quantitatively by a model that treats the electrophoretic and hydrodynamic forces. The conductance steps that occur when RecA-DNA enters the nanopore change from conductance decreases at high salt to conductance increases at low salt, which allows the apparent charge of the RecA-DNA filament to be extracted. The combination of conductance measurements with local force spectroscopy increases the potential for future solid-state nanopore screening devices.
Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Adam R
AR
Hall
Stijn
S
van Dorp
Serge G
SG
Lemay
Cees
C
Dekker
D003198:Computer Simulation; D004247:DNA / Q000737:chemistry* / Q000648:ultrastructure*; D004563:Electrochemistry / Q000379:methods*; D004586:Electrophoresis / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D011485:Protein Binding; D011938:Rec A Recombinases / Q000737:chemistry* / Q000648:ultrastructure; D012666:Semiconductors; D013314:Stress, Mechanical
D004247:DNA; D011938:Rec A Recombinases