1gqt: Difference between revisions

Revision as of 17:54, 2 May 2008

ACTIVATION OF RIBOKINASE BY MONOVALENT CATIONS

OverviewOverview

Carbohydrate kinases frequently require a monovalent cation for their activity. The physical basis of this phenomenon is, however, usually unclear. We report here that Escherichia coli ribokinase is activated by potassium with an apparent K(d) of 5 mM; the enzyme should therefore be fully activated under physiological conditions. Cesium can be used as an alternative ion, with an apparent K(d) of 17 mM. An X-ray structure of ribokinase in the presence of cesium was solved and refined at 2.34 A resolution. The cesium ion was bound between two loops immediately adjacent to the anion hole of the active site. The buried location of the site suggests that conformational changes will accompany ion binding, thus providing a direct mechanism for activation. Comparison with structures of a related enzyme, the adenosine kinase of Toxoplasma gondii, support this proposal. This is apparently the first instance in which conformational activation of a carbohydrate kinase by a monovalent cation has been assigned a clear structural basis. The mechanism is probably general to ribokinases, to some adenosine kinases, and to other members of the larger family. A careful re-evaluation of the biochemical and structural data is suggested for other enzyme systems.

About this StructureAbout this Structure

1GQT is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

ReferenceReference

Activation of ribokinase by monovalent cations., Andersson CE, Mowbray SL, J Mol Biol. 2002 Jan 18;315(3):409-19. PMID:11786021 Page seeded by OCA on Fri May 2 17:54:24 2008

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OCA

@@ Line 1: / Line 1: @@
 [[Image:1gqt.jpg|left|200px]]
- {{Structure
+<!--
-|PDB= 1gqt |SIZE=350|CAPTION= <scene name='initialview01'>1gqt</scene>, resolution 2.34&Aring;
+The line below this paragraph, containing "STRUCTURE_1gqt", creates the "Structure Box" on the page.
-|SITE= <scene name='pdbsite=AC1:Rib+Binding+Site+For+Chain+D'>AC1</scene>
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=ACP:PHOSPHOMETHYLPHOSPHONIC+ACID+ADENYLATE+ESTER'>ACP</scene>, <scene name='pdbligand=CS:CESIUM+ION'>CS</scene>, <scene name='pdbligand=RIB:RIBOSE'>RIB</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Ribokinase Ribokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.1.15 2.7.1.15] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE=
+-->
-|DOMAIN=
+{{STRUCTURE_1gqt|  PDB=1gqt  |  SCENE=  }}
-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1gqt FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1gqt OCA], [http://www.ebi.ac.uk/pdbsum/1gqt PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1gqt RCSB]</span>
-}}
 '''ACTIVATION OF RIBOKINASE BY MONOVALENT CATIONS'''
@@ Line 28: / Line 25: @@
 [[Category: Andersson, C E.]]
 [[Category: Mowbray, S L.]]
-[[Category: activation by monovalent cation]]
+[[Category: Activation by monovalent cation]]
-[[Category: binding of monovalent cation]]
+[[Category: Binding of monovalent cation]]
-[[Category: carbohydrate kinase]]
+[[Category: Carbohydrate kinase]]
-[[Category: induced fit]]
+[[Category: Induced fit]]
-[[Category: ribose]]
+[[Category: Ribose]]
-[[Category: transferase]]
+[[Category: Transferase]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 17:54:24 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 20:49:32 2008''