1hj6
From Proteopedia
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| - | [[Image:1hj6.jpg|left|200px]]<br /><applet load="1hj6" size=" | + | [[Image:1hj6.jpg|left|200px]]<br /><applet load="1hj6" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1hj6, resolution 2.0Å" /> | caption="1hj6, resolution 2.0Å" /> | ||
'''ISOCITRATE DEHYDROGENASE S113E MUTANT COMPLEXED WITH ISOPROPYLMALATE, NADP+ AND MAGNESIUM (FLASH-COOLED)'''<br /> | '''ISOCITRATE DEHYDROGENASE S113E MUTANT COMPLEXED WITH ISOPROPYLMALATE, NADP+ AND MAGNESIUM (FLASH-COOLED)'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1HJ6 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 MG, IPM, NAP and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Isocitrate_dehydrogenase_(NADP(+)) Isocitrate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.42 1.1.1.42] Known structural/functional Sites: <scene name='pdbsite=IPM:Isopropylmalate Binding Site'>IPM</scene>, <scene name='pdbsite=MG:Mg2+ Cofactor Binding Site'>MG</scene> and <scene name='pdbsite=NAP:Nadp Cofactor Binding Site'>NAP</scene>. Full crystallographic information is available from [http:// | + | 1HJ6 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=MG:'>MG</scene>, <scene name='pdbligand=IPM:'>IPM</scene>, <scene name='pdbligand=NAP:'>NAP</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Isocitrate_dehydrogenase_(NADP(+)) Isocitrate dehydrogenase (NADP(+))], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.42 1.1.1.42] Known structural/functional Sites: <scene name='pdbsite=IPM:Isopropylmalate+Binding+Site'>IPM</scene>, <scene name='pdbsite=MG:Mg2++Cofactor+Binding+Site'>MG</scene> and <scene name='pdbsite=NAP:Nadp+Cofactor+Binding+Site'>NAP</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HJ6 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: phosphorylation]] | [[Category: phosphorylation]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Feb 3 09:49:29 2008'' |
Revision as of 07:49, 3 February 2008
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ISOCITRATE DEHYDROGENASE S113E MUTANT COMPLEXED WITH ISOPROPYLMALATE, NADP+ AND MAGNESIUM (FLASH-COOLED)
Overview
Isocitrate dehydrogenase (IDH) catalyzes the oxidative decarboxylation of, isocitrate and has negligible activity toward other (R)-malate-type, substrates. The S113E mutant of IDH significantly improves its ability to, utilize isopropylmalate as a substrate and switches the substrate, specificity (k(cat)/K(M)) from isocitrate to isopropylmalate. To, understand the structural basis for this switch in substrate specificity, we have determined the crystal structure of IDH S113E in a complex with, isopropylmalate, NADP, and Mg(2+) to 2.0 A resolution. On the basis of a, comparison with previously determined structures, we identify distinct, changes caused by the amino acid substitution and by the binding of, substrates. The S113E complex exhibits alterations in global and active, site conformations compared with other IDH structures that include loop, and helix conformational changes near the active site. In addition, the, angle of the hinge that relates the two domains was altered in this, structure, which suggests that the S113E substitution and the binding of, substrates act together to promote catalysis of isopropylmalate. Ligand, binding results in reorientation of the active site helix that contains, residues 113 through 116. E113 exhibits new interactions, including van, der Waals contacts with the isopropyl group of isopropylmalate and a, hydrogen bond with N115, which in turn forms a hydrogen bond with NADP. In, addition, the loop and helix regions that bind NADP are altered, as is the, loop that connects the NADP binding region to the active site helix, changing the relationship between substrates and enzyme. In combination, these interactions appear to provide the basis for the switch in substrate, specificity.
About this Structure
1HJ6 is a Single protein structure of sequence from Escherichia coli with , , and as ligands. Active as Isocitrate dehydrogenase (NADP(+)), with EC number 1.1.1.42 Known structural/functional Sites: , and . Full crystallographic information is available from OCA.
Reference
Structural basis for a change in substrate specificity: crystal structure of S113E isocitrate dehydrogenase in a complex with isopropylmalate, Mg2+, and NADP., Doyle SA, Beernink PT, Koshland DE Jr, Biochemistry. 2001 Apr 10;40(14):4234-41. PMID:11284679
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