Puzzle 21
Sequence (5' to 3'):
CCGGACGAGGUGCGCCGUACCCGGUCAGGACAAGACGGCGC
Puzzle: Guanidine III Riboswitch
Crystal structure kindly provided by: David M J Lilley
Reference: Structure of the Guanidine III Riboswitch. Cell Chem Biol. 2017 Nov 16;24(11):1407-1415.e2. doi: 10.1016/j.chembiol.2017.08.021. Epub 2017 Oct 5.