7BY8

Malate Dehydrogenase from Geobacillus stearothermophilus (gs-MDH)

Summary for 7BY8

• Entry DOI: 10.2210/pdb7by8/pdb
• Descriptor: Malate dehydrogenase (2 entities in total)
• Functional Keywords: malate dehydrogenase, oxidoreductase
• Biological source: Geobacillus stearothermophilus
• Total number of polymer chains: 4
• Total formula weight: 143729.25

Authors

Shimozawa, Y.,Nakamura, T.,Himiyama, T.,Nishiya, Y. (deposition date: 2020-04-22, release date: 2021-03-24, Last modification date: 2023-11-29)

Primary citation

Shimozawa, Y.,Himiyama, T.,Nakamura, T.,Nishiya, Y.
Structural analysis and reaction mechanism of malate dehydrogenase from Geobacillus stearothermophilus.
J.Biochem., 170:97-105, 2021

PubMed Abstract: Malate dehydrogenase (MDH) catalyzes the reversible reduction of oxaloacetate (OAA) to L-malate using nicotinamide adenine dinucleotide hydrogen. MDH has two characteristic loops, the mobile loop and the catalytic loop, in the active site. On binding to the substrate, the enzyme undergoes a structural change from the open-form, with an open conformation of the mobile loop, to the closed-form, with the loop in a closed conformation. In this study, three crystals of MDH from a moderate thermophile, Geobacillus stearothermophilus (gs-MDH) were used to determine four different enzyme structures (resolutions, 1.95-2.20 Å), each of which was correspondingly assigned to its four catalytic states. Two OAA-unbound structures exhibited the open-form, while the other two OAA-bound structures exhibited both the open- and closed-form. The structural analysis suggested that the binding of OAA to the open-form gs-MDH promotes conformational change in the mobile loop and simultaneously activates the catalytic loop. The mutations on the key amino acid residues involving the proposed catalytic mechanism significantly affected the gs-MDH activity, supporting our hypothesis. These findings contribute to the elucidation of the detailed molecular mechanism underlying the substrate recognition and structural switching during the MDH catalytic cycle.

PubMed: 33723609
DOI: 10.1093/jb/mvab027

Experimental method

X-RAY DIFFRACTION (1.945 Å)