Proposed structural basis for dominant negativity by Asw. (a) Hint dimer with conformations of His114 and Trp123 as determined crystallographically  and a model of adenosine 5'-monophosphoramide substrates in ball-and-stick representation. (b) Proposed structure of an Asw (pink)-Hint (blue) heterodimer with predicted conformation of Asw Gln127 extending into the vicinity of Hint His114 and the bound Hint substrate. (c) Stereo view of a close-up superposition of the Hint homodimer (green) depicted in (a) with the Asw-Hint heterodimer (pink and blue) depicted in (b). The amino acids in green are in the active Hint homodimer conformation. Note that Asw Gln127 (in pink) is proposed to alter the conformation of Hint His114 (in blue) such that catalysis from the Hint active site is depressed.