Magnetic torque tweezers: measuring torsional stiffness in DNA and RecA-DNA filaments.
We introduce magnetic torque tweezers, which enable direct single-molecule measurements of torque. Our measurements of the effective torsional stiffness C of dsDNA indicated a substantial force dependence, with C = approximately 40 nm at low forces up to C = approximately 100 nm at high forces. The initial torsional stiffness of RecA filaments was nearly twofold larger than that for dsDNA, yet at moderate torques further build-up of torsional strain was prevented.
Lipfert
Jan
J
Department of Bionanoscience, Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands.
Kerssemakers
Jacob W J
JW
Jager
Tessa
T
Dekker
Nynke H
NH
D004247:DNA / Q000737:chemistry*; D007700:Kinetics; D008280:Magnetics / Q000295:instrumentation / Q000379:methods*; D015416:Maillard Reaction; D018715:Microscopy, Video / Q000379:methods; D011938:Rec A Recombinases / Q000737:chemistry* / Q000378:metabolism; D012399:Rotation; D013314:Stress, Mechanical; D019415:Torque
D004247:DNA; D011938:Rec A Recombinases