The structure of apo human glutamate dehydrogenase details subunit communication and allostery

Thomas Smith, Timothy Schmidt, Jie Fang, Jane Wu, Gary Siuzdak, Charles A. Stanley

Research output: Contribution to journalArticle

101 Citations (Scopus)

Abstract

The structure of human glutamate dehydrogenase (GDH) has been determined in the absence of active site and regulatory ligands. Compared to the structures of bovine GDH that were complexed with coenzyme and substrate, the NAD binding domain is rotated away from the glutamate-binding domain. The electron density of this domain is more disordered the further it is from the pivot helix. Mass spectrometry results suggest that this is likely due to the apo form being more dynamic than the closed form. The antenna undergoes significant conformational changes as the catalytic cleft opens. The ascending helix in the antenna moves in a clockwise manner and the helix in the descending strand contracts in a manner akin to the relaxation of an extended spring. A number of spontaneous mutations in this antenna region cause the hyperinsulinism/hyperammonemia syndrome by decreasing GDH sensitivity to the inhibitor, GTP. Since these residues do not directly contact the bound GTP, the conformational changes in the antenna are apparently crucial to GTP inhibition. In the open conformation, the GTP binding site is distorted such that it can no longer bind GTP. In contrast, ADP binding benefits by the opening of the catalytic cleft since R463 on the pivot helix is pushed PROOF into contact distance with the β-phosphate of ADP. These results support the previous proposal that purines regulate GDH activity by altering the dynamics of the NAD binding domain. Finally, a possible structural mechanism for negative cooperativity is presented.

Original languageEnglish (US)
Pages (from-to)765-777
Number of pages13
JournalJournal of Molecular Biology
Volume318
Issue number3
DOIs
StatePublished - 2002
Externally publishedYes

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Glutamate Dehydrogenase
Guanosine Triphosphate
Communication
NAD
Adenosine Diphosphate
Purines
Coenzymes
Contracts
Glutamic Acid
Mass Spectrometry
Catalytic Domain
Phosphates
Binding Sites
Electrons
Ligands
Mutation

Keywords

  • Allostery
  • Human glutamate dehydrogenase
  • Hyperinsulinism
  • Subunit communication

ASJC Scopus subject areas

  • Virology

Cite this

The structure of apo human glutamate dehydrogenase details subunit communication and allostery. / Smith, Thomas; Schmidt, Timothy; Fang, Jie; Wu, Jane; Siuzdak, Gary; Stanley, Charles A.

In: Journal of Molecular Biology, Vol. 318, No. 3, 2002, p. 765-777.

Research output: Contribution to journalArticle

Smith, Thomas ; Schmidt, Timothy ; Fang, Jie ; Wu, Jane ; Siuzdak, Gary ; Stanley, Charles A. / The structure of apo human glutamate dehydrogenase details subunit communication and allostery. In: Journal of Molecular Biology. 2002 ; Vol. 318, No. 3. pp. 765-777.
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