Glutamate dehydrogenase: Structure of a hyperinsulinism mutant, corrections to the atomic model, and insights into a regulatory site

Proteins. 2019 Jan;87(1):41-50. doi: 10.1002/prot.25620. Epub 2018 Nov 18.


Mammalian glutamate dehydrogenase (GDH) has complex allosteric regulation and the loss of GTP inhibition causes the hyperinsulinism/hyperammonemia syndrome (HHS) where insulin is hypersecreted upon consumption of protein. The archetypical HHS lesion is H454Y and lies in the GTP binding pocket. To better understand the mechanism of HHS, we determined the crystal structure of H454Y. When the bovine GDH crystal structures were minimized to prepare for further computational analysis, unusually large deviations were found at the allosteric NADH binding site due to chemical sequence errors. Notably, 387 lies in an allosteric where several activators and inhibitors bind and should be lysine rather than asparagine. All structures were re-refined and the consequence of this sequence error on NADH binding was calculated using free energy perturbation. The binding free energy penalty going from the correct to incorrect sequence found is +5 kcal/mol per site and therefore has a significant impact on drug development. BROADER AUDIENCE ABSTRACT: Glutamate dehydrogenase is a key enzyme involved in amino acid catabolism. As such, it is heavily regulated in animals by a wide array of metabolites. The importance of this regulation is most apparent in a genetic disorder called hyperinsulinism/hyperammonemia (HHS) where patients hypersecrete insulin upon the consumption of protein. We determined the atomic structure of one of these HHS mutants to better understand the disease and also analyzed an allosteric regulatory site.

Keywords: allostery; binding free energy; glutamate dehydrogenase; insulin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Allosteric Regulation
  • Glutamate Dehydrogenase / chemistry*
  • Glutamate Dehydrogenase / genetics
  • Glutamate Dehydrogenase / metabolism
  • Guanosine Triphosphate / metabolism*
  • Humans
  • Hyperinsulinism / enzymology
  • Hyperinsulinism / genetics*
  • Hypoglycemia / enzymology
  • Hypoglycemia / genetics*
  • Models, Molecular
  • Mutant Proteins / chemistry*
  • Mutant Proteins / genetics
  • Mutant Proteins / metabolism
  • Mutation*
  • Protein Conformation


  • Mutant Proteins
  • Guanosine Triphosphate
  • Glutamate Dehydrogenase

Supplementary concepts

  • Hyperinsulinemic hypoglycemia, familial, 6