The crystal structure of a Polerovirus exoribonuclease-resistant RNA shows how diverse sequences are integrated into a conserved fold

Structure of the PLRV xrRNA. (A) Secondary structure of the crystallized PLRV RNA, with matching colors to Figure 1B,C. Engineered nucleotides (see Materials and Methods) are shown in lower case. Non-Watson–Crick base pairs are according to the Leontis–Westhof annotation (Leontis and Westhof 2001). (B) Ribbon representation of the PLRV xrRNA_LT structure in colors to match (A), over that from SCNMV in gray (two orthogonal views). (C) Side-by-side comparison of the conserved structural core involving J1/2, L2B, and P2. (D) The PLRV and SCNMV xrRNA_LTs both crystallize as a domain-swap dimer, in which the intramolecular pseudoknot is replaced by intermolecular base-pairing (indicated by a star).