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Updated: Jun 25, 2026

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
Structure of a D-tagatose 3-epimerase-related protein from the hyperthermophilic bacterium Thermotoga maritima
Haruhiko Sakuraba1, Kazunari Yoneda, Takenori Satomura
1Department of Applied Biological Science, Kagawa University, Ikenobe, Miki-cho, Kita-gun, Japan.
Abstract:
The crystal structure of a D-tagatose 3-epimerase-related protein (TM0416p) encoded by the hypothetical open reading frame TM0416 in the genome of the hyperthermophilic bacterium Thermotoga maritima was determined at a resolution of 2.2 A. The asymmetric unit contained two homologous subunits and a dimer was generated by twofold symmetry. The main-chain coordinates of the enzyme monomer proved to be similar to those of D-tagatose 3-epimerase from Pseudomonas cichorii and D-psicose 3-epimerase from Agrobacterium tumefaciens; however, TM0416p exhibited a unique solvent-accessible substrate-binding pocket that reflected the absence of an alpha-helix that covers the active-site cleft in the two aforementioned ketohexose 3-epimerases. In addition, the residues responsible for creating a hydrophobic environment around the substrate in TM0416p differ entirely from those in the other two enzymes. Collectively, these findings suggest that the substrate specificity of TM0416p is likely to differ substantially from those of other D-tagatose 3-epimerase family enzymes.
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