1NXU: Crystal Structure Of E. Coli Hypothetical Oxidoreductase Yiak Northeast Structural Genomics Consortium Target Er82

Escherichia coli YiaK catalyzes the reduction of 2,3-diketo-L-gulonate in the presence of NADH. It belongs to a large family of oxidoreductases that is conserved in archaea, bacteria, and eukaryotes but shows no sequence homology to other proteins. We report here the crystal structures at up to 2.0-A resolution of YiaK alone and in complex with NAD-tartrate. YiaK has a new polypeptide backbone fold and a novel mode of recognizing the NAD cofactor. In addition, NAD is bound in an unusual conformation, at the interface of a dimer of the enzyme. The crystallographic analysis unexpectedly revealed the binding of tartrate in the active site. Enzyme kinetics studies confirm that tartrate and the related D-malate are inhibitors of YiaK. In contrast to most other enzymes where substrate binding produces a more closed conformation, the binding of NAD-tartrate to YiaK produces a more open active site. The free enzyme conformation is incompatible with NAD binding. His(44) is likely the catalytic residue of the enzyme.
PDB ID: 1NXUDownload
MMDB ID: 22453
PDB Deposition Date: 2003/2/11
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 1NXU: dimeric; determined by author and by software (PISA)
Molecular Components in 1NXU
Label Count Molecule
Proteins (2 molecules)
Hypothetical Oxidoreductase Yiak(Gene symbol: yiaK)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB