1p3w
From Proteopedia
(New page: 200px<br /><applet load="1p3w" size="450" color="white" frame="true" align="right" spinBox="true" caption="1p3w, resolution 2.1Å" /> '''X-ray crystal structu...) |
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| - | [[Image:1p3w.gif|left|200px]]<br /><applet load="1p3w" size=" | + | [[Image:1p3w.gif|left|200px]]<br /><applet load="1p3w" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1p3w, resolution 2.1Å" /> | caption="1p3w, resolution 2.1Å" /> | ||
'''X-ray crystal structure of E. coli IscS'''<br /> | '''X-ray crystal structure of E. coli IscS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | IscS is a widely distributed cysteine desulfurase that catalyzes the | + | IscS is a widely distributed cysteine desulfurase that catalyzes the pyridoxal phosphate-dependent desulfuration of L-cysteine and plays a central role in the delivery of sulfur to a variety of metabolic pathways. We report the crystal structure of Escherichia coli IscS to a resolution of 2.1A. The crystals belong to the space group P2(1)2(1)2(1) and have unit cell dimensions a=73.70A, b=101.97A, c=108.62A (alpha=beta=gamma=90 degrees ). Molecular replacement with the Thermotoga maritima NifS model was used to determine phasing, and the IscS model was refined to an R=20.6% (R(free)=23.6%) with two molecules per asymmetric unit. The structure of E.coli IscS is similar to that of T.maritima NifS with nearly identical secondary structure and an overall backbone r.m.s. difference of 1.4A. However, in contrast to NifS a peptide segment containing the catalytic cysteine residue (Cys328) is partially ordered in the IscS structure. This segment of IscS (residues 323-335) forms a surface loop directed away from the active site pocket. Cys328 is positioned greater than 17A from the pyridoxal phosphate cofactor, suggesting that a large conformational change must occur during catalysis in order for Cys328 to participate in nucleophilic attack of a pyridoxal phosphate-bound cysteine substrate. Modeling suggests that rotation of this loop may allow movement of Cys328 to within approximately 3A of the pyridoxal phosphate cofactor. |
==About this Structure== | ==About this Structure== | ||
| - | 1P3W 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 PLP as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1P3W 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=PLP:'>PLP</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1P3W OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Cupp-Vickery, J | + | [[Category: Cupp-Vickery, J R.]] |
[[Category: Urbina, H.]] | [[Category: Urbina, H.]] | ||
| - | [[Category: Vickery, L | + | [[Category: Vickery, L E.]] |
[[Category: PLP]] | [[Category: PLP]] | ||
[[Category: csdb]] | [[Category: csdb]] | ||
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[[Category: nifs]] | [[Category: nifs]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:24:48 2008'' |
Revision as of 12:24, 21 February 2008
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X-ray crystal structure of E. coli IscS
Overview
IscS is a widely distributed cysteine desulfurase that catalyzes the pyridoxal phosphate-dependent desulfuration of L-cysteine and plays a central role in the delivery of sulfur to a variety of metabolic pathways. We report the crystal structure of Escherichia coli IscS to a resolution of 2.1A. The crystals belong to the space group P2(1)2(1)2(1) and have unit cell dimensions a=73.70A, b=101.97A, c=108.62A (alpha=beta=gamma=90 degrees ). Molecular replacement with the Thermotoga maritima NifS model was used to determine phasing, and the IscS model was refined to an R=20.6% (R(free)=23.6%) with two molecules per asymmetric unit. The structure of E.coli IscS is similar to that of T.maritima NifS with nearly identical secondary structure and an overall backbone r.m.s. difference of 1.4A. However, in contrast to NifS a peptide segment containing the catalytic cysteine residue (Cys328) is partially ordered in the IscS structure. This segment of IscS (residues 323-335) forms a surface loop directed away from the active site pocket. Cys328 is positioned greater than 17A from the pyridoxal phosphate cofactor, suggesting that a large conformational change must occur during catalysis in order for Cys328 to participate in nucleophilic attack of a pyridoxal phosphate-bound cysteine substrate. Modeling suggests that rotation of this loop may allow movement of Cys328 to within approximately 3A of the pyridoxal phosphate cofactor.
About this Structure
1P3W is a Single protein structure of sequence from Escherichia coli with as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of IscS, a cysteine desulfurase from Escherichia coli., Cupp-Vickery JR, Urbina H, Vickery LE, J Mol Biol. 2003 Jul 25;330(5):1049-59. PMID:12860127
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