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Updated: Feb 28, 2026
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Published on: May 12, 2023
Mg2+ -Dependent High Mechanical Anisotropy of Three-Way-Junction pRNA as Revealed by Single-Molecule Force
Yang Sun1, Weishuai Di1, Yiran Li1
1Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, 22 Hankou Road, Nanjing, Jiang Su, 210093, P.R. China.
Abstract:
Mechanical anisotropy is ubiquitous in biological tissues but is hard to reproduce in synthetic biomaterials. Developing molecular building blocks with anisotropic mechanical response is the key towards engineering anisotropic biomaterials. The three-way-junction (3WJ) pRNA, derived from ϕ29 DNA packaging motor, shows strong mechanical anisotropy upon Mg2+ binding. In the absence of Mg2+ , 3WJ-pRNA is mechanically weak without noticeable mechanical anisotropy. In the presence of Mg2+ , the unfolding forces can differ by more than 4-fold along different pulling directions, ranging from about 47 pN to about 219 pN. Mechanical anisotropy of 3WJ-pRNA stems from pulling direction dependent cooperativity for the rupture of two Mg2+ binding sites, which is a novel mechanism for the mechanical anisotropy of biomacromolecules. It is anticipated that 3WJ-pRNA can be used as a key element for the construction of biomaterials with controllable mechanical anisotropy.
