4da5: Difference between revisions
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==Choline Kinase alpha acts through a double-displacement kinetic mechanism involving enzyme isomerisation, as determined through enzyme and inhibitor kinetics and structural biology== | |||
<StructureSection load='4da5' size='340' side='right' caption='[[4da5]], [[Resolution|resolution]] 2.40Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[4da5]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4DA5 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4DA5 FirstGlance]. <br> | |||
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=0H7:(3R)-1-AZABICYCLO[2.2.2]OCT-3-YL[BIS(5-CHLOROTHIOPHEN-2-YL)]METHANOL'>0H7</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | |||
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">CHKA, CHK, CKI ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens])</td></tr> | |||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4da5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4da5 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=4da5 RCSB], [http://www.ebi.ac.uk/pdbsum/4da5 PDBsum]</span></td></tr> | |||
</table> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Choline Kinase is a key component of the Kennedy pathway that converts choline into a number of structural and signalling lipids that are essential for cell growth and survival. One member of the family, Choline Kinase-alpha (ChoKalpha) is frequently up-regulated in human cancers, and expression of ChoKalpha is sufficient to transform cells. Consequently ChoKalpha has been studied as a potential target for therapeutic agents in cancer research. Despite great interest in the enzyme, mechanistic studies have not been reported. In this study, a combination of initial velocity and product inhibition studies, together with the kinetic and structural characterisation of a novel ChoKalpha inhibitor is used to support a mechanism of action for human ChoKalpha. Substrate and inhibition kinetics are consistent with an iso double displacement mechanism, in which the gamma-phosphate from ATP is transferred to choline in two distinct steps via a phospho-enzyme intermediate. Co-crystal structures, and existing site-specific mutation studies, support an important role for Asp306, in stabilising the phospho-enzyme intermediate. The kinetics also indicate a distinct kinetic (isomerisation) step associated with product release, which may be attributed to a conformational change in the protein to disrupt an interaction between Asp306 and the phosphocholine product, facilitating product release. This study describes a mechanism for ChoKalpha that is unusual amongst kinases, and highlights the availability of different enzyme states that can be exploited for drug discovery. | |||
Kinetic and mechanistic characterisation of Choline Kinase-alpha.,Hudson CS, Knegtel RM, Brown K, Charlton PA, Pollard JR Biochim Biophys Acta. 2013 Jun;1834(6):1107-16. doi:, 10.1016/j.bbapap.2013.02.008. Epub 2013 Feb 13. PMID:23416529<ref>PMID:23416529</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
== | ==See Also== | ||
*[[Choline kinase|Choline kinase]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Brown, K | [[Category: Brown, K]] | ||
[[Category: Charlton, P | [[Category: Charlton, P]] | ||
[[Category: Hudson, C | [[Category: Hudson, C]] | ||
[[Category: Pollard, J | [[Category: Pollard, J]] | ||
[[Category: Cytoplasmic]] | [[Category: Cytoplasmic]] | ||
[[Category: Kinase]] | [[Category: Kinase]] | ||
[[Category: Signal transduction]] | [[Category: Signal transduction]] | ||
[[Category: Transferase-transferase inhibitor complex]] | [[Category: Transferase-transferase inhibitor complex]] | ||
Revision as of 13:00, 21 December 2014
Choline Kinase alpha acts through a double-displacement kinetic mechanism involving enzyme isomerisation, as determined through enzyme and inhibitor kinetics and structural biologyCholine Kinase alpha acts through a double-displacement kinetic mechanism involving enzyme isomerisation, as determined through enzyme and inhibitor kinetics and structural biology
Structural highlights
Publication Abstract from PubMedCholine Kinase is a key component of the Kennedy pathway that converts choline into a number of structural and signalling lipids that are essential for cell growth and survival. One member of the family, Choline Kinase-alpha (ChoKalpha) is frequently up-regulated in human cancers, and expression of ChoKalpha is sufficient to transform cells. Consequently ChoKalpha has been studied as a potential target for therapeutic agents in cancer research. Despite great interest in the enzyme, mechanistic studies have not been reported. In this study, a combination of initial velocity and product inhibition studies, together with the kinetic and structural characterisation of a novel ChoKalpha inhibitor is used to support a mechanism of action for human ChoKalpha. Substrate and inhibition kinetics are consistent with an iso double displacement mechanism, in which the gamma-phosphate from ATP is transferred to choline in two distinct steps via a phospho-enzyme intermediate. Co-crystal structures, and existing site-specific mutation studies, support an important role for Asp306, in stabilising the phospho-enzyme intermediate. The kinetics also indicate a distinct kinetic (isomerisation) step associated with product release, which may be attributed to a conformational change in the protein to disrupt an interaction between Asp306 and the phosphocholine product, facilitating product release. This study describes a mechanism for ChoKalpha that is unusual amongst kinases, and highlights the availability of different enzyme states that can be exploited for drug discovery. Kinetic and mechanistic characterisation of Choline Kinase-alpha.,Hudson CS, Knegtel RM, Brown K, Charlton PA, Pollard JR Biochim Biophys Acta. 2013 Jun;1834(6):1107-16. doi:, 10.1016/j.bbapap.2013.02.008. Epub 2013 Feb 13. PMID:23416529[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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