Download MendeleyBinding of non-catalytic ATP to human hexokinase I highlights the structural components for enzyme-membrane association control.
Rosano, C., Sabini, E., Rizzi, M., Deriu, D., Murshudov, G., Bianchi, M., Serafini, G., Magnani, M., Bolognesi, M.(1999) Structure 7: 1427-1437
- PubMed: 10574795
- DOI: https://doi.org/10.1016/s0969-2126(00)80032-5
- Primary Citation of Related Structures:
1QHA - PubMed Abstract:
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. The crystal structure of human hexokinase I has been determined at 2.25 A 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. 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.
Organizational Affiliation:
Dipartimento di Fisica - INFM, Centro Biotecnologie Avanzate - IST, Universita' di Genova, Genova, 10. I-16132, Italy.
