Fig. 7: Structural origin of the mechanical anisotropy of ZIKV xrRNA1.

a The interactions (native HBs and Mg²⁺ clamps) belonging to the same residue–residue pair are combined into a group, which is renumbered according to the secondary structure (left). A detailed view of non-canonical base pair interactions as well as the Mg²⁺ clamps is also included. b, d Definition of different loading stages for 5′-end pulling (b) and 3′-end pulling (d). c, e Correlation analysis of residue–residue interaction for 5′-end pulling (c), 3′-end pulling (e) at 3 different loading stages. f The intricate interaction network (or force-bearing structure) in the center of ring structure is showed in bonds, which is proposed to be responsible for the stronger mechanical resistance of xrRNA1 to 5′-end loading, whereas the 5′-stretch and PK2 enclosing the ring are highlighted in red and cyan, respectively. g Schematic illustration of shearing mode and unzipping mode. Source data for c and e are provided as a Source Data file.