(A) NOESY spectrum of DenvSLAsh showing H6/H8–H6/H8 interactions; the secondary structure of DenvSLAsh is shown on the right. This spectrum was recorded at 25°C in 10 mM potassium phosphate buffer (pH 6.5, 90% H2O/10% D2O). The following NOE interactions, G23H8–A24H8, U33H6–A34H8 and A34–C10H6, within the three-way junction establish coaxial stacking of the top and side stem–loops. (B) A close-up view of the three-way junction in DenvSLAsh from the lowest energy structure (left) and superposition of 10 representative NMR structure (right). Ade34 stacks within the coaxial helix, between Cyt10 at the end of top stem and Ura33 at the end of the side stem–loop. (C) The lowest energy structure of DenvSLAsh is shown in cartoon representation superposed on the SAXS model; the SAXS results were not used for NMR refinement and therefore provide independent validation of the structure.
