1s5t
From Proteopedia
(New page: 200px<br /><applet load="1s5t" size="450" color="white" frame="true" align="right" spinBox="true" caption="1s5t, resolution 2.30Å" /> '''Crystal Structure An...) |
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| - | [[Image:1s5t.gif|left|200px]]<br /><applet load="1s5t" size=" | + | [[Image:1s5t.gif|left|200px]]<br /><applet load="1s5t" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1s5t, resolution 2.30Å" /> | caption="1s5t, resolution 2.30Å" /> | ||
'''Crystal Structure Analysis of a mutant of DIHYDRODIPICOLINATE SYNTHASE--residue thr44 to val44'''<br /> | '''Crystal Structure Analysis of a mutant of DIHYDRODIPICOLINATE SYNTHASE--residue thr44 to val44'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Dihydrodipicolinate synthase (DHDPS, EC 4.2.1.52) catalyses the | + | Dihydrodipicolinate synthase (DHDPS, EC 4.2.1.52) catalyses the branchpoint reaction of lysine biosynthesis in plants and microbes: the condensation of (S)-aspartate-beta-semialdehyde and pyruvate. The crystal structure of wild-type DHDPS has been published to 2.5A, revealing a tetrameric molecule comprised of four identical (beta/alpha)(8)-barrels, each containing one active site. Previous workers have hypothesised that the catalytic mechanism of the enzyme involves a catalytic triad of amino acid residues, Tyr133, Thr44 and Tyr107, which provide a proton shuttle to transport protons from the active site to solvent. We have tested this hypothesis using site-directed mutagenesis to produce three mutant enzymes: DHDPS-Y133F, DHDPS-T44V and DHDPS-Y107F. Each of these mutants has substantially reduced activity, consistent with the catalytic triad hypothesis. We have determined each mutant crystal structure to at least 2.35A resolution and compared the structures to the wild-type enzyme. All mutant enzymes crystallised in the same space group as the wild-type form and only minor differences in structure are observed. These results suggest that the catalytic triad is indeed in operation in wild-type DHDPS. |
==About this Structure== | ==About this Structure== | ||
| - | 1S5T is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/Dihydrodipicolinate_synthase Dihydrodipicolinate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.52 4.2.1.52] Full crystallographic information is available from [http:// | + | 1S5T is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/Dihydrodipicolinate_synthase Dihydrodipicolinate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.52 4.2.1.52] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1S5T OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Dobson, R | + | [[Category: Dobson, R C.J.]] |
| - | [[Category: Gerrard, J | + | [[Category: Gerrard, J A.]] |
[[Category: Valegard, K.]] | [[Category: Valegard, K.]] | ||
[[Category: dihydrodipicolinate]] | [[Category: dihydrodipicolinate]] | ||
[[Category: synthase]] | [[Category: synthase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:58:15 2008'' |
Revision as of 12:58, 21 February 2008
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Crystal Structure Analysis of a mutant of DIHYDRODIPICOLINATE SYNTHASE--residue thr44 to val44
Overview
Dihydrodipicolinate synthase (DHDPS, EC 4.2.1.52) catalyses the branchpoint reaction of lysine biosynthesis in plants and microbes: the condensation of (S)-aspartate-beta-semialdehyde and pyruvate. The crystal structure of wild-type DHDPS has been published to 2.5A, revealing a tetrameric molecule comprised of four identical (beta/alpha)(8)-barrels, each containing one active site. Previous workers have hypothesised that the catalytic mechanism of the enzyme involves a catalytic triad of amino acid residues, Tyr133, Thr44 and Tyr107, which provide a proton shuttle to transport protons from the active site to solvent. We have tested this hypothesis using site-directed mutagenesis to produce three mutant enzymes: DHDPS-Y133F, DHDPS-T44V and DHDPS-Y107F. Each of these mutants has substantially reduced activity, consistent with the catalytic triad hypothesis. We have determined each mutant crystal structure to at least 2.35A resolution and compared the structures to the wild-type enzyme. All mutant enzymes crystallised in the same space group as the wild-type form and only minor differences in structure are observed. These results suggest that the catalytic triad is indeed in operation in wild-type DHDPS.
About this Structure
1S5T is a Single protein structure of sequence from Escherichia coli. Active as Dihydrodipicolinate synthase, with EC number 4.2.1.52 Full crystallographic information is available from OCA.
Reference
The crystal structure of three site-directed mutants of Escherichia coli dihydrodipicolinate synthase: further evidence for a catalytic triad., Dobson RC, Valegard K, Gerrard JA, J Mol Biol. 2004 Apr 23;338(2):329-39. PMID:15066435
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