Figure 2.

Cisplatin coordination by guanine bases resembles coordination of magnesium ions. (A and C) Side-by-side comparison of cisplatin-modified guanine residues in 16S rRNA (light yellow) and 23S rRNA (light blue). Panels (B and D) show the same sites in the untreated 70S ribosome (PDB ID: 4Y4P (23)). Cisplatin-modified nucleotides are highlighted in yellow. The color coding for atoms is the same as in Figure 1. Note that cisplatin binding is observed in idiosyncratic RNA folds, in which N7-atoms of purine residues normally coordinate magnesium ions (in the untreated ribosome) and are located adjacent to the RNA phosphates capable of stabilizing the cisplatin moiety by electrostatic interactions.