Fig. 3

Key elements of the SL1067 structure. a The snap formed by 2Nap15 and the sugar ring of dG2 combines the stem and loop regions of SL1067. b Multilayer stacking of 2Nap7, the base of dU10 and the base of dA9 is capped with O4ʹ of dU8. c O4ʹ(dG13) caps the Nap-base stack between dU10 and dU14. d The hydrophobic cluster on SL1067. The dU7 and 2Nap8 residues form a classical edge-to-face π interaction. Two other pairs of edge-to-face π interactions are formed between 2Nap10 and 2Nap15, and 2Nap14 and dG11. 2Nap8 makes face-to-face stacking with 2Nap10. e Four-layer base stacking is capped with the O4ʹ of the dU15 sugar ring on the top and the O4ʹ of dA5 sugar ring on the bottom. The stacking is further strengthened by the base pairings of dA9-dU15, dA16-dU8 and dG17-dG6. f In the loop region, the dG12 and dG13 base rings form face-to-face stacking and dG11 protrudes toward a hydrophobic pocket on the IL-1α surface