1bu6
From Proteopedia
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CRYSTAL STRUCTURES OF ESCHERICHIA COLI GLYCEROL KINASE AND THE MUTANT A65T IN AN INACTIVE TETRAMER: CONFORMATIONAL CHANGES AND IMPLICATIONS FOR ALLOSTERIC REGULATION
Overview
BACKGROUND: Glycerol kinase (GK) from Escherichia coli is a, velocity-modulated (V system) enzyme that has three allosteric effectors, with independent mechanisms: fructose-1,6-bisphosphate (FBP); the, phosphocarrier protein IIAGlc; and adenosine nucleotides. The enzyme, exists in solution as functional dimers that associate reversibly to form, tetramers. GK is a member of a superfamily of ATPases that share a common, ATPase domain and are thought to undergo a large conformational change as, an intrinsic step in their catalytic cycle. Members of this family include, actin, hexokinase and the heat shock protein hsc70. RESULTS: We report, here the crystal structures of GK and a mutant of GK (Ala65-->Thr) in, complex with glycerol and ADP. Crystals of both enzymes contain the same, 222 symmetric tetramer. The functional dimer is identical to that, described previously for the IIAGlc-GK complex structure. The tetramer, interface is significantly different, however, with a relative 22.3, degrees rotation and 6.34 A translation of one functional dimer. The, overall monomer structure is unchanged except for two regions: the, IIAGlc-binding site undergoes a structural rearrangement and residues, 230-236 become ordered and bind orthophosphate at the tetramer interface., We also report the structure of a second mutant of GK (IIe474-->Asp) in, complex with IIAGlc; this complex crystallized isomorphously to the wild, type IIAGlc-GK complex. Site-directed mutants of GK with substitutions at, the IIAGlc-binding site show significantly altered kinetic and regulatory, properties, suggesting that the conformation of the binding site is linked, to the regulation of activity. CONCLUSIONS: We conclude that the new, tetramer structure presented here is an inactive form of the, physiologically relevant tetramer. The structure and location of the, orthophosphate-binding site is consistent with it being part of the, FBP-binding site. Mutational analysis and the structure of the, IIAGlc-GK(IIe474-->Asp) complex suggest the conformational transition of, the IIAGlc-binding site to be an essential aspect of IIAGlc regulation.
About this Structure
1BU6 is a Single protein structure of sequence from Escherichia coli with SO4 and GOL as ligands. Active as Glycerol kinase, with EC number 2.7.1.30 Full crystallographic information is available from OCA.
Reference
Glycerol kinase from Escherichia coli and an Ala65-->Thr mutant: the crystal structures reveal conformational changes with implications for allosteric regulation., Feese MD, Faber HR, Bystrom CE, Pettigrew DW, Remington SJ, Structure. 1998 Nov 15;6(11):1407-18. PMID:9817843
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