Figure 3.
Cartoon and ball-and-stick diagrams of the metX SAM-II riboswitch from the Sargasso Sea metagenome. (a) Cartoon depicting the tertiary structure of the SAM-II riboswitch in the bound state. The coordinates are from PDB entry 2QWY. (b) Ball-and-stick diagram of the structure in (a) showing interactions with SAM; red dashed lines indicate putative electrostatic interactions. (c) Close up view of the interaction between A19 and A47 showing the potential for chemical modification. (See the text for details).