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1szu
From Proteopedia
(New page: 200px<br /><applet load="1szu" size="450" color="white" frame="true" align="right" spinBox="true" caption="1szu, resolution 2.52Å" /> '''The structure of gam...) |
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| - | [[Image:1szu.gif|left|200px]]<br /><applet load="1szu" size=" | + | [[Image:1szu.gif|left|200px]]<br /><applet load="1szu" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1szu, resolution 2.52Å" /> | caption="1szu, resolution 2.52Å" /> | ||
'''The structure of gamma-aminobutyrate aminotransferase mutant: V241A'''<br /> | '''The structure of gamma-aminobutyrate aminotransferase mutant: V241A'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The E. coli isozyme of gamma-aminobutyrate aminotransferase (GABA-AT) is a | + | The E. coli isozyme of gamma-aminobutyrate aminotransferase (GABA-AT) is a tetrameric pyridoxal phosphate-dependent enzyme that catalyzes transamination between primary amines and alpha-keto acids. The roles of the active site residues V241, E211, and I50 in the GABA-AT mechanism have been probed by site-directed mutagenesis. The beta-branched side chain of V241 facilitates formation of external aldimine intermediates with primary amine substrates, while E211 provides charge compensation of R398 selectively in the primary amine half-reaction and I50 forms a hydrophobic lid at the top of the substrate binding site. The structures of the I50Q, V241A, and E211S mutants were solved by X-ray crystallography to resolutions of 2.1, 2.5, and 2.52 A, respectively. The structure of GABA-AT is similar in overall fold and active site structure to that of dialkylglycine decarboxylase, which catalyzes both transamination and decarboxylation half-reactions in its normal catalytic cycle. Therefore, an attempt was made to convert GABA-AT into a decarboxylation-dependent aminotransferase similar to dialkylglycine decarboxylase by systematic mutation of E. coli GABA-AT active site residues. Two of the twelve mutants presented, E211S/I50G/C77K and E211S/I50H/V80D, have approximately 10-fold higher decarboxylation activities than the wild-type enzyme, and the E211S/I50H/V80D has formally changed the reaction specificity to that of a decarboxylase. |
==About this Structure== | ==About this Structure== | ||
| - | 1SZU 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 SO4, EDO, PLP and PMP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/4-aminobutyrate_transaminase 4-aminobutyrate transaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.19 2.6.1.19] Full crystallographic information is available from [http:// | + | 1SZU 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=SO4:'>SO4</scene>, <scene name='pdbligand=EDO:'>EDO</scene>, <scene name='pdbligand=PLP:'>PLP</scene> and <scene name='pdbligand=PMP:'>PMP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/4-aminobutyrate_transaminase 4-aminobutyrate transaminase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.19 2.6.1.19] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SZU OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Fisher, A | + | [[Category: Fisher, A J.]] |
[[Category: Jin, X.]] | [[Category: Jin, X.]] | ||
| - | [[Category: Langston, J | + | [[Category: Langston, J A.]] |
[[Category: Liu, W.]] | [[Category: Liu, W.]] | ||
| - | [[Category: Peterson, P | + | [[Category: Peterson, P E.]] |
| - | [[Category: Toney, M | + | [[Category: Toney, M D.]] |
[[Category: Zhou, X.]] | [[Category: Zhou, X.]] | ||
[[Category: EDO]] | [[Category: EDO]] | ||
| Line 27: | Line 27: | ||
[[Category: gaba-at]] | [[Category: gaba-at]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:08:17 2008'' |
Revision as of 13:08, 21 February 2008
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The structure of gamma-aminobutyrate aminotransferase mutant: V241A
Overview
The E. coli isozyme of gamma-aminobutyrate aminotransferase (GABA-AT) is a tetrameric pyridoxal phosphate-dependent enzyme that catalyzes transamination between primary amines and alpha-keto acids. The roles of the active site residues V241, E211, and I50 in the GABA-AT mechanism have been probed by site-directed mutagenesis. The beta-branched side chain of V241 facilitates formation of external aldimine intermediates with primary amine substrates, while E211 provides charge compensation of R398 selectively in the primary amine half-reaction and I50 forms a hydrophobic lid at the top of the substrate binding site. The structures of the I50Q, V241A, and E211S mutants were solved by X-ray crystallography to resolutions of 2.1, 2.5, and 2.52 A, respectively. The structure of GABA-AT is similar in overall fold and active site structure to that of dialkylglycine decarboxylase, which catalyzes both transamination and decarboxylation half-reactions in its normal catalytic cycle. Therefore, an attempt was made to convert GABA-AT into a decarboxylation-dependent aminotransferase similar to dialkylglycine decarboxylase by systematic mutation of E. coli GABA-AT active site residues. Two of the twelve mutants presented, E211S/I50G/C77K and E211S/I50H/V80D, have approximately 10-fold higher decarboxylation activities than the wild-type enzyme, and the E211S/I50H/V80D has formally changed the reaction specificity to that of a decarboxylase.
About this Structure
1SZU is a Single protein structure of sequence from Escherichia coli with , , and as ligands. Active as 4-aminobutyrate transaminase, with EC number 2.6.1.19 Full crystallographic information is available from OCA.
Reference
Kinetic and crystallographic analysis of active site mutants of Escherichia coli gamma-aminobutyrate aminotransferase., Liu W, Peterson PE, Langston JA, Jin X, Zhou X, Fisher AJ, Toney MD, Biochemistry. 2005 Mar 1;44(8):2982-92. PMID:15723541
Page seeded by OCA on Thu Feb 21 15:08:17 2008
Categories: 4-aminobutyrate transaminase | Escherichia coli | Single protein | Fisher, A J. | Jin, X. | Langston, J A. | Liu, W. | Peterson, P E. | Toney, M D. | Zhou, X. | EDO | PLP | PMP | SO4 | Gaba-at
