Figure 2: Surfaces and tunnels of TmoA.
From: Structural basis for biomolecular recognition in overlapping binding sites in a diiron enzyme system
(a) Surface of TmoA (blue) alone, showing residues involved in T4moC binding (gold), entrance to the substrate channel (light blue), residues Asn202 (green) and Gln228 (purple), and six residues unique to the T4moHC interface (white). (b) Surface of TmoA from the T4moHD complex, showing 53 residues within 5 Å of T4moD that are unique to the T4moHD complex (orange), 17 residues in common with the T4moHC complex (gold), and six residues unique to the T4moHC complex (white). (c) Mesh mapping (raspberry and blue) of the open tunnel from solvent to the active site in TmoA from the T4moHC complex. (d) Mesh mapping of the closed tunnel in the T4moHD complex caused by repositioning of TmoA residues Leu208 and Asp211 relative to their positions in T4moHC (dark grey). These shifts are produced by steric contacts with T4moD residues Ala47 and Tyr48, causing complete collapse of the entrance to the substrate channel at the fork position.
