1hkb
CRYSTAL STRUCTURE OF RECOMBINANT HUMAN BRAIN HEXOKINASE TYPE I COMPLEXED WITH GLUCOSE AND GLUCOSE-6-PHOSPHATECRYSTAL STRUCTURE OF RECOMBINANT HUMAN BRAIN HEXOKINASE TYPE I COMPLEXED WITH GLUCOSE AND GLUCOSE-6-PHOSPHATE
Structural highlights
Disease[HXK1_HUMAN] Defects in HK1 are the cause of hexokinase deficiency (HK deficiency) [MIM:235700]. HK deficiency is a rare autosomal recessive disease with nonspherocytic hemolytic anemia as the predominant clinical feature. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: Hexokinase I is the pacemaker of glycolysis in brain tissue. The type I isozyme exhibits unique regulatory properties in that physiological levels of phosphate relieve potent inhibition by the product, glucose-6-phosphate (Gluc-6-P). The 100 kDa polypeptide chain of hexokinase I consists of a C-terminal (catalytic) domain and an N-terminal (regulatory) domain. Structures of ligated hexokinase I should provide a basis for understanding mechanisms of catalysis and regulation at an atomic level. RESULTS: The complex of human hexokinase I with glucose and Gluc-6-P (determined to 2.8 A resolution) is a dimer with twofold molecular symmetry. The N- and C-terminal domains of one monomer interact with the C- and N-terminal domains, respectively, of the symmetry-related monomer. The two domains of a monomer are connected by a single alpha helix and each have the fold of yeast hexokinase. Salt links between a possible cation-binding loop of the N-terminal domain and a loop of the C-terminal domain may be important to regulation. Each domain binds single glucose and Gluc-6-P molecules in proximity to each other. The 6-phosphoryl group of bound Gluc-6-P at the C-terminal domain occupies the putative binding site for ATP, whereas the 6-phosphoryl group at the N-terminal domain may overlap the binding site for phosphate. CONCLUSIONS: The binding synergism of glucose and Gluc-6-P probably arises out of the mutual stabilization of a common (glucose-bound) conformation of hexokinase I. Conformational changes in the N-terminal domain in response to glucose, phosphate, and/or Gluc-6-P may influence the binding of ATP to the C-terminal domain. The mechanism of regulation of hexokinase: new insights from the crystal structure of recombinant human brain hexokinase complexed with glucose and glucose-6-phosphate.,Aleshin AE, Zeng C, Bourenkov GP, Bartunik HD, Fromm HJ, Honzatko RB Structure. 1998 Jan 15;6(1):39-50. PMID:9493266[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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