2gn2
From Proteopedia
(New page: 200px<br /><applet load="2gn2" size="450" color="white" frame="true" align="right" spinBox="true" caption="2gn2, resolution 2.50Å" /> '''Crystal structure of...) |
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| - | [[Image:2gn2.gif|left|200px]]<br /><applet load="2gn2" size=" | + | [[Image:2gn2.gif|left|200px]]<br /><applet load="2gn2" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2gn2, resolution 2.50Å" /> | caption="2gn2, resolution 2.50Å" /> | ||
'''Crystal structure of tetrameric biodegradative threonine deaminase (TdcB) from Salmonella typhimurium in complex with CMP at 2.5A resolution (Hexagonal form)'''<br /> | '''Crystal structure of tetrameric biodegradative threonine deaminase (TdcB) from Salmonella typhimurium in complex with CMP at 2.5A resolution (Hexagonal form)'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC | + | Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC 4.3.1.19), biosynthetic and biodegradative, which catalyze the deamination of l-threonine to alpha-ketobutyrate, are present in Escherichia coli and Salmonella typhimurium. Biodegradative threonine deaminase (TdcB) catalyzes the first reaction in the anaerobic breakdown of l-threonine to propionate. TdcB, unlike the biosynthetic threonine deaminase, is insensitive to l-isoleucine and is activated by AMP. In the present study, TdcB from S. typhimurium was cloned and overexpressed in E. coli. In the presence of AMP or CMP, the recombinant enzyme was converted to the tetrameric form accompanied by significant enzyme activation. To provide insights into ligand-mediated oligomerization and enzyme activation, crystal structures of S. typhimurium TdcB and its complex with CMP were determined. In the native structure, TdcB is in a dimeric form, whereas in the TdcB.CMP complex, it exists in a tetrameric form with 222 symmetry and appears as a dimer of dimers. Tetrameric TdcB binds to four molecules of CMP, two at each of the dimer interfaces. Comparison of the dimer structure in the ligand (CMP)-free and -bound forms suggests that the changes induced by ligand binding at the dimer interface are essential for tetramerization. The differences observed in the tertiary and quaternary structures of TdcB in the absence and presence of CMP appear to account for enzyme activation and increased binding affinity for l-threonine. Comparison of TdcB with related pyridoxal 5'-phosphate-dependent enzymes points to structural and mechanistic similarities. |
==About this Structure== | ==About this Structure== | ||
| - | 2GN2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with NA and C5P as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Threonine_ammonia-lyase Threonine ammonia-lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.3.1.19 4.3.1.19] Full crystallographic information is available from [http:// | + | 2GN2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with <scene name='pdbligand=NA:'>NA</scene> and <scene name='pdbligand=C5P:'>C5P</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Threonine_ammonia-lyase Threonine ammonia-lyase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.3.1.19 4.3.1.19] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2GN2 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Threonine ammonia-lyase]] | [[Category: Threonine ammonia-lyase]] | ||
| - | [[Category: Murthy, M | + | [[Category: Murthy, M R.N.]] |
| - | [[Category: Savithri, H | + | [[Category: Savithri, H S.]] |
| - | [[Category: Simanshu, D | + | [[Category: Simanshu, D K.]] |
[[Category: C5P]] | [[Category: C5P]] | ||
[[Category: NA]] | [[Category: NA]] | ||
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[[Category: threonine dehydratase]] | [[Category: threonine dehydratase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:33:21 2008'' |
Revision as of 15:33, 21 February 2008
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Crystal structure of tetrameric biodegradative threonine deaminase (TdcB) from Salmonella typhimurium in complex with CMP at 2.5A resolution (Hexagonal form)
Overview
Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC 4.3.1.19), biosynthetic and biodegradative, which catalyze the deamination of l-threonine to alpha-ketobutyrate, are present in Escherichia coli and Salmonella typhimurium. Biodegradative threonine deaminase (TdcB) catalyzes the first reaction in the anaerobic breakdown of l-threonine to propionate. TdcB, unlike the biosynthetic threonine deaminase, is insensitive to l-isoleucine and is activated by AMP. In the present study, TdcB from S. typhimurium was cloned and overexpressed in E. coli. In the presence of AMP or CMP, the recombinant enzyme was converted to the tetrameric form accompanied by significant enzyme activation. To provide insights into ligand-mediated oligomerization and enzyme activation, crystal structures of S. typhimurium TdcB and its complex with CMP were determined. In the native structure, TdcB is in a dimeric form, whereas in the TdcB.CMP complex, it exists in a tetrameric form with 222 symmetry and appears as a dimer of dimers. Tetrameric TdcB binds to four molecules of CMP, two at each of the dimer interfaces. Comparison of the dimer structure in the ligand (CMP)-free and -bound forms suggests that the changes induced by ligand binding at the dimer interface are essential for tetramerization. The differences observed in the tertiary and quaternary structures of TdcB in the absence and presence of CMP appear to account for enzyme activation and increased binding affinity for l-threonine. Comparison of TdcB with related pyridoxal 5'-phosphate-dependent enzymes points to structural and mechanistic similarities.
About this Structure
2GN2 is a Single protein structure of sequence from Salmonella typhimurium with and as ligands. Active as Threonine ammonia-lyase, with EC number 4.3.1.19 Full crystallographic information is available from OCA.
Reference
Crystal structures of Salmonella typhimurium biodegradative threonine deaminase and its complex with CMP provide structural insights into ligand-induced oligomerization and enzyme activation., Simanshu DK, Savithri HS, Murthy MR, J Biol Chem. 2006 Dec 22;281(51):39630-41. Epub 2006 Oct 17. PMID:17046821
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