1glf: Difference between revisions

[[Image:1glf.jpg|left|200px]]<br /><applet load="1glf" size="350" color="white" frame="true" align="right" spinBox="true"  

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--&gt;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--&gt;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--&gt;Asp) complex suggest the conformational transition of the IIAGlc-binding site to be an essential aspect of IIAGlc regulation.

1GLF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=ADP:'>ADP</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glycerol_kinase Glycerol kinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.1.30 2.7.1.30] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GLF OCA].  

[[Category: Bystrom, C E.]]

[[Category: Faber, H R.]]

[[Category: Feese, M D.]]

[[Category: Pettigrew, D W.]]

[[Category: Remington, S J.]]

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