Binding of non-catalytic ATP to human hexokinase I highlights the structural components for enzyme-membrane association control

Camillo Rosano, Elisabetta Sabini, Menico Rizzi, Daniela Deriu, Garib Murshudov, Marzia Bianchi, Giordano Serafini, Mauro Magnani, Martino Bolognesi

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Hexokinase I sets the pace of glycolysis in the brain, catalyzing the ATP-dependent phosphorylation of glucose. The catalytic properties of hexokinase I are dependent on product inhibition as well as on the action of phosphate. In vivo, a large fraction of hexokinase I is bound to the mitochondrial outer membrane, where the enzyme adopts a tetrameric assembly. The mitochondrion-bound hexokinase I is believed to optimize the ATP/ADP exchange between glucose phosphorylation and the mitochondrial oxidative phosphorylation reactions. Results: The crystal structure of human hexokinase I has been determined at 2.25 Å resolution. The overall structure of the enzyme is in keeping with the closed conformation previously observed in yeast hexokinase. One molecule of the ATP analogue AMP-PNP is bound to each N-terminal domain of the dimeric enzyme in a surface cleft, showing specific interactions with the nucleotide, and localized positive electrostatic potential. The molecular symmetry brings the two bound AMP-PNP molecules, at the centre of two extended surface regions, to a common side of the dimeric hexokinase I molecule. Conclusions: The binding of AMP-PNP to a protein site separated from the catalytic centre of human hexokinase I can be related to the role played by some nucleotides in dissociating the enzyme from the mitochondrial membrane, and helps in defining the molecular regions of hexokinase I that are expected to be in contact with the mitochondrion. The structural information presented here is in keeping with monoclonal antibody mapping of the free and mitochondrion-bound forms of the enzyme, and with sequence analysis of hexokinases that differ in their mitochondria binding properties.

Original languageEnglish
Pages (from-to)1427-1437
Number of pages11
JournalStructure
Volume7
Issue number11
DOIs
Publication statusPublished - Nov 15 1999

Keywords

  • ATP
  • Glucose recognition
  • Glycolysis
  • Human hexokinase I
  • Mitochondrial membrane

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology

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