Steve Ealick's Research Group
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Steve Ealick's Research Group |
Pyrococcus furiosus Quinolinate Synthase
PDB file:
Description:
Pyrococcus furiosus quinolinate synthase (PfQS) catalyzes the condensation of iminoaspartate and dihydroxyacetone phosphate to form quinolinate, the universal precursor in the de novo biosynthesis of nicotinamide adenine dinucleotide (NAD). The structure was solved using single anomalous dispersion methods and compared to that of Pyrococcus horikoshii quinolinate synthase (PhQS; PDB =1WZU)
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The monomer consists of three domains each of which have the similar topology.The three domains are connected by flexible linkers, with each of the linkers containing a Cys residue that is conserved among all QS proteins.
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Click the images to enlarge. |
| PfQS forms a dimer related by 2-fold symmetry in the unit cell The dimer interface is formed by domain 2, the connection between domain 2 and 3, and the connection between domain 3 and the C-terminal α-helices. This formation leaves domain 3 completely exposed to the solvent. |
Click the image to enlarge. |
The active site appears to be in a cleft between domains
1 and 2. This is based on the fact that conserved residues were identified
from sequence comparison for QS from different organisms and these
residues tend to cluster in that region. The figure at left shows important
residues from PfQS (blue with dimer interactions in red) and
those of PhQS (gray with substrate analog malate in ball-and-stick). |
Click the image to enlarge. |
Reference
To be published by Soriano.... Ealick.
