Fig. 4: Comparison of structural changes in the apo forms of the enzymes.
From: Engineering the protein dynamics of an ancestral luciferase
AncHLD-RLuc (white), AncINS (chain A light blue, chain B slate), AncFT (salmon), RLuc8 (chain A pale cyan, chain B light teal). a Top view of the active site. The putative catalytic pentad and α5 helix occupy the same position in all proteins, but the α4 helix adopts different conformations. b Crystal structure of the whole protein, with the main access tunnel (identified using Caver 3.0223) shown as spheres. The outward/inward movement of the α4 helix causes opening/closing of the tunnel. c Front view of the main tunnel. The black arrow indicates the visible constriction due to closure of the α4 helix. d The size of the active site cavity is changed by repositioning of amino acids in the α4 helix. e The size of the main tunnel mouth is changed by movements of the α4 helix and L9 loop.
