2tsc
From Proteopedia
(New page: 200px<br /><applet load="2tsc" size="450" color="white" frame="true" align="right" spinBox="true" caption="2tsc, resolution 1.97Å" /> '''STRUCTURE, MULTIPLE ...) |
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| - | [[Image:2tsc.gif|left|200px]]<br /><applet load="2tsc" size=" | + | [[Image:2tsc.gif|left|200px]]<br /><applet load="2tsc" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2tsc, resolution 1.97Å" /> | caption="2tsc, resolution 1.97Å" /> | ||
'''STRUCTURE, MULTIPLE SITE BINDING, AND SEGMENTAL ACCOMODATION IN THYMIDYLATE SYNTHASE ON BINDING D/UMP AND AN ANTI-FOLATE'''<br /> | '''STRUCTURE, MULTIPLE SITE BINDING, AND SEGMENTAL ACCOMODATION IN THYMIDYLATE SYNTHASE ON BINDING D/UMP AND AN ANTI-FOLATE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The structure of Escherichia coli thymidylate synthase (TS) complexed with | + | The structure of Escherichia coli thymidylate synthase (TS) complexed with the substrate dUMP and an analogue of the cofactor methylenetetrahydrofolate was solved by multiple isomorphous replacement and refined at 1.97-A resolution to a residual of 18% for all data (16% for data greater than 2 sigma) for a highly constrained structure. All residues in the structure are clearly resolved and give a very high confidence in total correctness of the structure. The ternary complex directly suggests how methylation of dUMP takes place. C-6 of dUMP is covalently bound to gamma S of Cys-198(146) during catalysis, and the reactants are surrounded by specific hydrogen bonds and hydrophobic interactions from conserved residues. Comparison with the independently solved structure of unliganded TS reveals a large conformation change in the enzyme, which closes down to sequester the reactants and several highly ordered water molecules within a cavernous active center, away from bulk solvent. A second binding site for the quinazoline ring of the cofactor analogue was discovered by withholding addition of reducing agent during crystal storage. The chemical change in the protein is slight, and from difference density maps modification of sulfhydryls is not directly responsible for blockade of the primary site. The site, only partially overlapping with the primary site, is also surrounded by conserved residues and thus may play a functional role. The ligand-induced conformational change is not a domain shift but involves the segmental accommodation of several helices, beta-strands, and loops that move as units against the beta-sheet interface between monomers. |
==About this Structure== | ==About this Structure== | ||
| - | 2TSC 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 UMP and CB3 as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Thymidylate_synthase Thymidylate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.1.1.45 2.1.1.45] Full crystallographic information is available from [http:// | + | 2TSC 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=UMP:'>UMP</scene> and <scene name='pdbligand=CB3:'>CB3</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Thymidylate_synthase Thymidylate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.1.1.45 2.1.1.45] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2TSC OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Thymidylate synthase]] | [[Category: Thymidylate synthase]] | ||
| - | [[Category: Montfort, W | + | [[Category: Montfort, W R.]] |
| - | [[Category: Stroud, R | + | [[Category: Stroud, R M.]] |
[[Category: CB3]] | [[Category: CB3]] | ||
[[Category: UMP]] | [[Category: UMP]] | ||
[[Category: transferase (methyltransferase)]] | [[Category: transferase (methyltransferase)]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:50:03 2008'' |
Revision as of 16:50, 21 February 2008
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STRUCTURE, MULTIPLE SITE BINDING, AND SEGMENTAL ACCOMODATION IN THYMIDYLATE SYNTHASE ON BINDING D/UMP AND AN ANTI-FOLATE
Overview
The structure of Escherichia coli thymidylate synthase (TS) complexed with the substrate dUMP and an analogue of the cofactor methylenetetrahydrofolate was solved by multiple isomorphous replacement and refined at 1.97-A resolution to a residual of 18% for all data (16% for data greater than 2 sigma) for a highly constrained structure. All residues in the structure are clearly resolved and give a very high confidence in total correctness of the structure. The ternary complex directly suggests how methylation of dUMP takes place. C-6 of dUMP is covalently bound to gamma S of Cys-198(146) during catalysis, and the reactants are surrounded by specific hydrogen bonds and hydrophobic interactions from conserved residues. Comparison with the independently solved structure of unliganded TS reveals a large conformation change in the enzyme, which closes down to sequester the reactants and several highly ordered water molecules within a cavernous active center, away from bulk solvent. A second binding site for the quinazoline ring of the cofactor analogue was discovered by withholding addition of reducing agent during crystal storage. The chemical change in the protein is slight, and from difference density maps modification of sulfhydryls is not directly responsible for blockade of the primary site. The site, only partially overlapping with the primary site, is also surrounded by conserved residues and thus may play a functional role. The ligand-induced conformational change is not a domain shift but involves the segmental accommodation of several helices, beta-strands, and loops that move as units against the beta-sheet interface between monomers.
About this Structure
2TSC is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Thymidylate synthase, with EC number 2.1.1.45 Full crystallographic information is available from OCA.
Reference
Structure, multiple site binding, and segmental accommodation in thymidylate synthase on binding dUMP and an anti-folate., Montfort WR, Perry KM, Fauman EB, Finer-Moore JS, Maley GF, Hardy L, Maley F, Stroud RM, Biochemistry. 1990 Jul 31;29(30):6964-77. PMID:2223754
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