2f1f
From Proteopedia
(New page: 200px<br /><applet load="2f1f" size="450" color="white" frame="true" align="right" spinBox="true" caption="2f1f, resolution 1.750Å" /> '''Crystal structure o...) |
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| - | [[Image:2f1f.gif|left|200px]]<br /><applet load="2f1f" size=" | + | [[Image:2f1f.gif|left|200px]]<br /><applet load="2f1f" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2f1f, resolution 1.750Å" /> | caption="2f1f, resolution 1.750Å" /> | ||
'''Crystal structure of the regulatory subunit of acetohydroxyacid synthase isozyme III from E. coli'''<br /> | '''Crystal structure of the regulatory subunit of acetohydroxyacid synthase isozyme III from E. coli'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The enzyme acetohydroxyacid synthase (AHAS) catalyses the first common | + | The enzyme acetohydroxyacid synthase (AHAS) catalyses the first common step in the biosynthesis of the three branched-chain amino acids. Enzymes in the AHAS family generally consist of regulatory and catalytic subunits. Here, we describe the first crystal structure of an AHAS regulatory subunit, the ilvH polypeptide, determined at a resolution of 1.75 A. IlvH is the regulatory subunit of one of three AHAS isozymes expressed in Escherichia coli, AHAS III. The protein is a dimer, with two beta alpha beta beta alpha beta ferredoxin domains in each monomer. The two N-terminal domains assemble to form an ACT domain structure remarkably close to the one predicted by us on the basis of the regulatory domain of 3-phosphoglycerate dehydrogenase (3PGDH). The two C-terminal domains combine so that their beta-sheets are roughly positioned back-to-back and perpendicular to the extended beta-sheet of the N-terminal ACT domain. On the basis of the properties of mutants and a comparison with 3PGDH, the effector (valine) binding sites can be located tentatively in two symmetrically related positions in the interface between a pair of N-terminal domains. The properties of mutants of the ilvH polypeptide outside the putative effector-binding site provide further insight into the functioning of the holoenzyme. The results of this study open avenues for further studies aimed at understanding the mechanism of regulation of AHAS by small-molecule effectors. |
==About this Structure== | ==About this Structure== | ||
| - | 2F1F 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 MG, P33 and 1PE as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Acetolactate_synthase Acetolactate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.6 2.2.1.6] Full crystallographic information is available from [http:// | + | 2F1F 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=MG:'>MG</scene>, <scene name='pdbligand=P33:'>P33</scene> and <scene name='pdbligand=1PE:'>1PE</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Acetolactate_synthase Acetolactate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.6 2.2.1.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2F1F OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Barak, Z.]] | [[Category: Barak, Z.]] | ||
| - | [[Category: Chipman, D | + | [[Category: Chipman, D M.]] |
[[Category: Kaplun, A.]] | [[Category: Kaplun, A.]] | ||
[[Category: Shaanan, B.]] | [[Category: Shaanan, B.]] | ||
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[[Category: ferredoxin fold]] | [[Category: ferredoxin fold]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:16:43 2008'' |
Revision as of 15:16, 21 February 2008
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Crystal structure of the regulatory subunit of acetohydroxyacid synthase isozyme III from E. coli
Overview
The enzyme acetohydroxyacid synthase (AHAS) catalyses the first common step in the biosynthesis of the three branched-chain amino acids. Enzymes in the AHAS family generally consist of regulatory and catalytic subunits. Here, we describe the first crystal structure of an AHAS regulatory subunit, the ilvH polypeptide, determined at a resolution of 1.75 A. IlvH is the regulatory subunit of one of three AHAS isozymes expressed in Escherichia coli, AHAS III. The protein is a dimer, with two beta alpha beta beta alpha beta ferredoxin domains in each monomer. The two N-terminal domains assemble to form an ACT domain structure remarkably close to the one predicted by us on the basis of the regulatory domain of 3-phosphoglycerate dehydrogenase (3PGDH). The two C-terminal domains combine so that their beta-sheets are roughly positioned back-to-back and perpendicular to the extended beta-sheet of the N-terminal ACT domain. On the basis of the properties of mutants and a comparison with 3PGDH, the effector (valine) binding sites can be located tentatively in two symmetrically related positions in the interface between a pair of N-terminal domains. The properties of mutants of the ilvH polypeptide outside the putative effector-binding site provide further insight into the functioning of the holoenzyme. The results of this study open avenues for further studies aimed at understanding the mechanism of regulation of AHAS by small-molecule effectors.
About this Structure
2F1F is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as Acetolactate synthase, with EC number 2.2.1.6 Full crystallographic information is available from OCA.
Reference
Structure of the regulatory subunit of acetohydroxyacid synthase isozyme III from Escherichia coli., Kaplun A, Vyazmensky M, Zherdev Y, Belenky I, Slutzker A, Mendel S, Barak Z, Chipman DM, Shaanan B, J Mol Biol. 2006 Mar 31;357(3):951-63. Epub 2006 Jan 18. PMID:16458324
Page seeded by OCA on Thu Feb 21 17:16:43 2008
Categories: Acetolactate synthase | Escherichia coli | Single protein | Barak, Z. | Chipman, D M. | Kaplun, A. | Shaanan, B. | Vyazmensky, M. | 1PE | MG | P33 | Act domain | Ferredoxin fold
