Journal
FRONTIERS IN MOLECULAR BIOSCIENCES
Volume 8, Issue -, Pages -Publisher
FRONTIERS MEDIA SA
DOI: 10.3389/fmolb.2021.605102
Keywords
optical trap; laser tweezers; single-molecule; DNA elasticity; calibration; microsphere size; force; trap stiffness
Categories
Funding
- NSF [MCB-1716219]
- NIH/NIGMS [R01GM118817]
- MBTG Fellowship award [T32 GM008326]
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This study demonstrates a more robust method for calibrating biophysical force and displacement measurements using DNA molecules, especially in the high force range. It shows how small variations in microsphere sizes can affect DNA length measurements and provides methods for correcting these errors. Additionally, it showcases how these measurements can be used to check the assumed linearities of system responses and assess trap compliance and positioning by combining microsphere imaging with DNA stretching.
We previously introduced the use of DNA molecules for calibration of biophysical force and displacement measurements with optical tweezers. Force and length scale factors can be determined from measurements of DNA stretching. Trap compliance can be determined by fitting the data to a nonlinear DNA elasticity model, however, noise/drift/offsets in the measurement can affect the reliability of this determination. Here we demonstrate a more robust method that uses a linear approximation for DNA elasticity applied to high force range (25-45 pN) data. We show that this method can be used to assess how small variations in microsphere sizes affect DNA length measurements and demonstrate methods for correcting for these errors. We further show that these measurements can be used to check assumed linearities of system responses. Finally, we demonstrate methods combining microsphere imaging and DNA stretching to check the compliance and positioning of individual traps.
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