Pattern of water bonding in the active site of MtSK. (a) Structure at 1.93 Å resolution (chloride ion and shikimate present, magnesium ion absent), (b) monomer B of the tetramer (chloride and magnesium ions present, shikimate absent), (c) monomer C of the tetramer (magnesium ion present, shikimate and chloride ion absent). The figures were generated using PyMOL (DeLano, 2004 ▶).