1a5b
From Proteopedia
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| - | [[Image:1a5b.gif|left|200px]]<br /> | + | [[Image:1a5b.gif|left|200px]]<br /><applet load="1a5b" size="450" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1a5b" size="450" color="white" frame="true" align="right" spinBox="true" | + | |
caption="1a5b, resolution 2.0Å" /> | caption="1a5b, resolution 2.0Å" /> | ||
'''CRYO-CRYSTALLOGRAPHY OF A TRUE SUBSTRATE, INDOLE-3-GLYCEROL PHOSPHATE, BOUND TO A MUTANT (ALPHA D60N) TRYPTOPHAN SYNTHASE ALPHA2BETA2 COMPLEX REVEALS THE CORRECT ORIENTATION OF ACTIVE SITE ALPHA GLU 49'''<br /> | '''CRYO-CRYSTALLOGRAPHY OF A TRUE SUBSTRATE, INDOLE-3-GLYCEROL PHOSPHATE, BOUND TO A MUTANT (ALPHA D60N) TRYPTOPHAN SYNTHASE ALPHA2BETA2 COMPLEX REVEALS THE CORRECT ORIENTATION OF ACTIVE SITE ALPHA GLU 49'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1A5B is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with K, IGP and PLP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Tryptophan_synthase Tryptophan synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.20 4.2.1.20] | + | 1A5B is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with K, IGP and PLP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Tryptophan_synthase Tryptophan synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.20 4.2.1.20] Known structural/functional Sites: <scene name='pdbsite=S1:True Substrate Igp Is Bound To The Active Site Of A-Subunit'>S1</scene> and <scene name='pdbsite=S2:Coenzyme Plp Binding Site'>S2</scene>. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1A5B OCA]. |
==Reference== | ==Reference== | ||
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[[Category: true substrate indole-3-glycerol phosphate in the a-subunit]] | [[Category: true substrate indole-3-glycerol phosphate in the a-subunit]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Dec 18 14:09:14 2007'' |
Revision as of 11:59, 18 December 2007
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CRYO-CRYSTALLOGRAPHY OF A TRUE SUBSTRATE, INDOLE-3-GLYCEROL PHOSPHATE, BOUND TO A MUTANT (ALPHA D60N) TRYPTOPHAN SYNTHASE ALPHA2BETA2 COMPLEX REVEALS THE CORRECT ORIENTATION OF ACTIVE SITE ALPHA GLU 49
Overview
The reversible cleavage of indole-3-glycerol by the alpha-subunit of, tryptophan synthase has been proposed to be catalyzed by alphaGlu49 and, alphaAsp60. Although previous x-ray crystallographic structures of the, tryptophan synthase alpha2beta2 complex showed an interaction between the, carboxylate of alphaAsp60 and the bound inhibitor indole-3-propanol, phosphate, the carboxylate of alphaGlu49 was too distant to play its, proposed role. To clarify the structural and functional roles of, alphaGlu49, we have determined crystal structures of a mutant (alphaD60N), alpha2beta2 complex in the presence and absence of the true substrate, indole-3-glycerol phosphate. The enzyme in the crystal cleaves, indole-3-glycerol phosphate very slowly at room temperature but not under, cryo-conditions of 95 K. The structure of the complex with the true, substrate obtained by cryo-crystallography reveals that indole-3-glycerol, phosphate and indole-3-propanol phosphate have similar binding modes but, different torsion angles. Most importantly, the side chain of alphaGlu49, interacts with 3-hydroxyl group of indole-3-glycerol phosphate as, proposed. The movement of the side chain of alphaGlu49 into an extended, conformation upon binding the true substrate provides evidence for an, induced fit mechanism. Our results demonstrate how cryo-crystallography, and mutagenesis can provide insight into enzyme mechanism.
About this Structure
1A5B is a Protein complex structure of sequences from Salmonella typhimurium with K, IGP and PLP as ligands. Active as Tryptophan synthase, with EC number 4.2.1.20 Known structural/functional Sites: and . Full crystallographic information is available from OCA.
Reference
Cryo-crystallography of a true substrate, indole-3-glycerol phosphate, bound to a mutant (alphaD60N) tryptophan synthase alpha2beta2 complex reveals the correct orientation of active site alphaGlu49., Rhee S, Miles EW, Davies DR, J Biol Chem. 1998 Apr 10;273(15):8553-5. PMID:9535826[[Category: mutation at position 60 (asp --> asn) in the a-subunit]]
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