3IWN:
reference: Recognition of the bacterial second messenger cyclic diguanylate by its cognate riboswitch., Kulshina N, Baird NJ, Ferre-D'Amare AR, Nat Struct Mol Biol. 2009 Dec;16(12):1212-7. Epub 2009 Nov 8. PMID: 19898478

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).