Abstract
DNA torsional elastic properties play a crucial role in DNA structure, topology, and the regulation of motor protein progression. However, direct measurements of these parameters are experimentally challenging. Here, we present a constant-extension method integrated into an angular optical trap to directly measure torque during DNA supercoiling. We measured the twist persistence length of extended DNA to be 22nm under an extremely low force (∼0.02 pN) and the twist persistence length of plectonemic DNA to be 24nm. In addition, we implemented a rigorous data analysis scheme that bridged our measurements with existing theoretical models of DNA torsional behavior. This comprehensive set of torsional parameters demonstrates that at least 20% of DNA supercoiling is partitioned into twist for both extended DNA and plectonemic DNA. This work provides a new experimental methodology, as well as an analytical and interpretational framework, which will enable, expand, and enhance future studies of DNA torsional properties.
Highlights
DNA torsional elastic properties play a crucial role in DNA structure, topology, and the regulation of motor protein progression
This comprehensive set of torsional parameters demonstrates that at least 20% of DNA supercoiling is partitioned into twist for both extended DNA and plectonemic DNA
The torsional stiffness of DNA impacts the topology and structure of DNA, and determines the resistance that a motor protein encounters while moving against DNA supercoiling
Summary
DNA torsional elastic properties play a crucial role in DNA structure, topology, and the regulation of motor protein progression. Both Ceff and P measure how much twist is introduced when turns are added to DNA and reflect the energetic cost to supercoil DNA (Supplemental Material [12]). An AOT can simultaneously measure the torque, angle, force, and position of a trapped birefringent particle such as a nanofabricated quartz cylinder [16,24,25] and is ideally suited for studying the torsional properties of DNA [16,17,18,26,27,28] (Supplemental Material [12]; Fig. S1).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
