1i29
From Proteopedia
(New page: 200px<br /><applet load="1i29" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i29, resolution 2.80Å" /> '''CRYSTAL STRUCTURE OF...) |
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| - | [[Image:1i29.gif|left|200px]]<br /><applet load="1i29" size=" | + | [[Image:1i29.gif|left|200px]]<br /><applet load="1i29" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1i29, resolution 2.80Å" /> | caption="1i29, resolution 2.80Å" /> | ||
'''CRYSTAL STRUCTURE OF CSDB COMPLEXED WITH L-PROPARGYLGLYCINE'''<br /> | '''CRYSTAL STRUCTURE OF CSDB COMPLEXED WITH L-PROPARGYLGLYCINE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Escherichia coli CsdB is a pyridoxal 5'-phosphate (PLP)-dependent enzyme | + | Escherichia coli CsdB is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes both cysteine desulfuration and selenocysteine deselenation. The enzyme has a high specific activity for L-selenocysteine relative to L-cysteine. On the other hand, its paralog, IscS, exhibits higher activity for L-cysteine, which acts as a sulfur donor during the biosynthesis of the iron-sulfur cluster and 4-thiouridine. The structure of CsdB complexed with L-propargylglycine was determined by X-ray crystallography at 2.8 A resolution. The overall polypeptide fold of the complex is similar to that of the uncomplexed enzyme, indicating that no significant structural change occurs upon formation of the complex. In the complex, propargylglycine forms a Schiff base with PLP, providing the features of the external aldimine formed in the active site. The Cys364 residue, which is essential for the activity of CsdB toward L-cysteine but not toward L-selenocysteine, is clearly visible on a loop of the extended lobe (Thr362-Arg375) in all enzyme forms studied, in contrast to the corresponding disordered loop (Ser321-Arg332) of the Thermotoga maritima NifS-like protein, which is closely related to IscS. The extended lobe of CsdB has an 11-residue deletion compared with that of the NifS-like protein. These facts suggest that the restricted flexibility of the Cys364-anchoring extended lobe in CsdB may be responsible for the ability of the enzyme to discriminate between selenium and sulfur. |
==About this Structure== | ==About this Structure== | ||
| - | 1I29 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 LPG and PLP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Selenocysteine_lyase Selenocysteine lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.4.1.16 4.4.1.16] Full crystallographic information is available from [http:// | + | 1I29 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=LPG:'>LPG</scene> and <scene name='pdbligand=PLP:'>PLP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Selenocysteine_lyase Selenocysteine lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.4.1.16 4.4.1.16] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1I29 OCA]. |
==Reference== | ==Reference== | ||
| - | Structure of external aldimine of Escherichia coli CsdB, an IscS/NifS homolog: implications for its specificity toward selenocysteine., Mihara H, Fujii T, Kato S, Kurihara T, Hata Y, Esaki N, J Biochem | + | Structure of external aldimine of Escherichia coli CsdB, an IscS/NifS homolog: implications for its specificity toward selenocysteine., Mihara H, Fujii T, Kato S, Kurihara T, Hata Y, Esaki N, J Biochem. 2002 May;131(5):679-85. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11983074 11983074] |
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Selenocysteine lyase]] | [[Category: Selenocysteine lyase]] | ||
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[[Category: external aldimine]] | [[Category: external aldimine]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:07:19 2008'' |
Revision as of 11:07, 21 February 2008
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CRYSTAL STRUCTURE OF CSDB COMPLEXED WITH L-PROPARGYLGLYCINE
Overview
Escherichia coli CsdB is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes both cysteine desulfuration and selenocysteine deselenation. The enzyme has a high specific activity for L-selenocysteine relative to L-cysteine. On the other hand, its paralog, IscS, exhibits higher activity for L-cysteine, which acts as a sulfur donor during the biosynthesis of the iron-sulfur cluster and 4-thiouridine. The structure of CsdB complexed with L-propargylglycine was determined by X-ray crystallography at 2.8 A resolution. The overall polypeptide fold of the complex is similar to that of the uncomplexed enzyme, indicating that no significant structural change occurs upon formation of the complex. In the complex, propargylglycine forms a Schiff base with PLP, providing the features of the external aldimine formed in the active site. The Cys364 residue, which is essential for the activity of CsdB toward L-cysteine but not toward L-selenocysteine, is clearly visible on a loop of the extended lobe (Thr362-Arg375) in all enzyme forms studied, in contrast to the corresponding disordered loop (Ser321-Arg332) of the Thermotoga maritima NifS-like protein, which is closely related to IscS. The extended lobe of CsdB has an 11-residue deletion compared with that of the NifS-like protein. These facts suggest that the restricted flexibility of the Cys364-anchoring extended lobe in CsdB may be responsible for the ability of the enzyme to discriminate between selenium and sulfur.
About this Structure
1I29 is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Selenocysteine lyase, with EC number 4.4.1.16 Full crystallographic information is available from OCA.
Reference
Structure of external aldimine of Escherichia coli CsdB, an IscS/NifS homolog: implications for its specificity toward selenocysteine., Mihara H, Fujii T, Kato S, Kurihara T, Hata Y, Esaki N, J Biochem. 2002 May;131(5):679-85. PMID:11983074
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