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![[Figure 3]](ag5038fig3mag.jpg)
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Figure 3
Comparison of the FAD-binding loop of Xcc4156 with the open and closed FAD-binding loops of Thal and PyrH. (a) The crystal contact that fixes the loop in chain A (blue; amino acids 47–58) of Xcc4156 in position. The backbone atoms of Val53 in chain A form two hydrogen bonds (pink) to the Gln470 side-chain amide in chain B of a symmetry-related molecule (grey). (b) Overlay of chain A of Xcc4156 (blue) with chain B (grey). Light blue dashed lines connect the same amino acids in both chains. The distances between Cα atoms are 0.8, 1.7, 2.5, 2.9, 2.6 and 1.0 Å for Glu49–Gly54. (c) The FAD-binding loop of Thal (green; PDB entry 6h43 chain A; amino acids 39–50) in the `open' conformation when no FAD is bound. (d) Upon FAD binding, the FAD-binding loop closes (PDB entry 6sls chain A). (e) In the absence of FAD, the FAD-binding loop of PyrH could not be modelled (red; PDB entry 2weu; amino acids 36–47). (f) When FAD is bound the loop closes, taking on the same conformation as in Thal (PDB entry 2wet chain A). In (a), (c), (d), (e) and (f), a conserved glutamate residue (Glu57 in Xcc4156 and Glu49 in both Thal and PyrH) is shown which acts as a sensor for FAD binding. (g) Overlay of apo Xcc4156 chain A (blue), apo Thal (green), Thal + FAD (green) and PyrH + FAD (red). Loops are open in the apo state and closed in the FAD-bound state. (h) Overlay of apo Xcc4156 chain A (blue) and Thal + FAD (green). In Xcc4156, an L-tartaric acid (TLA) molecule is bound at the site that coordinates a phosphate of FAD in other halogenases. |
![[Figure 3]](ag5038fig3.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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