Summary information and primary citation
- PDB-id
- 2ygh; DSSR-derived features in text and JSON formats
- Class
- RNA
- Method
- X-ray (2.6 Å)
- Summary
- Sam-i riboswitch with a g2na mutation in the kink turn in complex with s-adenosylmethionine
- Reference
- Schroeder KT, Daldrop P, Lilley DMJ (2011): "RNA Tertiary Interactions in a Riboswitch Stabilize the Structure of a Kink Turn." Structure, 19, 1233. doi: 10.1016/J.STR.2011.07.003.
- Abstract
- The kink turn is a widespread RNA motif that introduces an acute kink into the axis of duplex RNA, typically comprising a bulge followed by a G⋅A and A⋅G pairs. The kinked conformation is stabilized by metal ions, or the binding of proteins including L7Ae. We now demonstrate a third mechanism for the stabilization of k-turn structure, involving tertiary interactions within a larger RNA structure. The SAM-I riboswitch contains an essential standard k-turn sequence that kinks a helix so that its terminal loop can make a long-range interaction. We find that some sequence variations in the k-turn within the riboswitch do not prevent SAM binding, despite preventing the folding of the k-turn in isolation. Furthermore, two crystal structures show that the sequence-variant k-turns are conventionally folded within the riboswitch. This study shows that the folded structure of the k-turn can be stabilized by tertiary interactions within a larger RNA structure.
