Structures of clindamycin and mirincamycin and the predicted interactions with 23S rRNA peptidyl transferase cavity. (A) Previous crystallography studies have shown A2058-Ec (red) is important for making contacts with clindamycin (Schlunzen et al. 2001), and the similarity of chemical structure of clindamycin and mirincamycin suggested that cross-resistance may occur. (B) Lowest energy dockings of clindamycin (green) and mirincamycin (magenta) to a homology model of the P. falciparum peptidyl transferase domain demonstrated that both molecules interact with the 23S rRNA in the same way, and thus, A2058C-Ec (red) was predicted to confer resistance to both lincosamide drugs.