1m3k
From Proteopedia
(New page: 200px<br /><applet load="1m3k" size="450" color="white" frame="true" align="right" spinBox="true" caption="1m3k, resolution 1.70Å" /> '''biosynthetic thiolas...) |
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| - | [[Image:1m3k.jpg|left|200px]]<br /><applet load="1m3k" size=" | + | [[Image:1m3k.jpg|left|200px]]<br /><applet load="1m3k" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1m3k, resolution 1.70Å" /> | caption="1m3k, resolution 1.70Å" /> | ||
'''biosynthetic thiolase, inactive C89A mutant'''<br /> | '''biosynthetic thiolase, inactive C89A mutant'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Biosynthetic thiolase catalyzes the formation of acetoacetyl-CoA from two | + | Biosynthetic thiolase catalyzes the formation of acetoacetyl-CoA from two molecules of acetyl-CoA. This is a key step in the synthesis of many biological compounds, including steroid hormones and ketone bodies. The thiolase reaction involves two chemically distinct steps; during acyl transfer, an acetyl group is transferred from acetyl-CoA to Cys89, and in the Claisen condensation step, this acetyl group is further transferred to a second molecule of acetyl-CoA, generating acetoacetyl-CoA. Here, new crystallographic data for Zoogloea ramigera biosynthetic thiolase are presented, covering all intermediates of the thiolase catalytic cycle. The high-resolution structures indicate that the acetyl group goes through four conformations while being transferred from acetyl-CoA via the acetylated enzyme to acetoacetyl-CoA. This transfer is catalyzed in a rigid cavity lined by mostly hydrophobic side chains, in addition to the catalytic residues Cys89, His348, and Cys378. The structures highlight the importance of an oxyanion hole formed by a water molecule and His348 in stabilizing the negative charge on the thioester oxygen atom of acetyl-CoA at two different steps of the reaction cycle. Another oxyanion hole, composed of the main chain nitrogen atoms of Cys89 and Gly380, complements a negative charge of the thioester oxygen anion of the acetylated intermediate, stabilizing the tetrahedral transition state of the Claisen condensation step. The reactivity of the active site may be modulated by hydrogen bonding networks extending from the active site toward the back of the molecule. |
==About this Structure== | ==About this Structure== | ||
| - | 1M3K is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zoogloea_ramigera Zoogloea ramigera] with SO4 and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Acetyl-CoA_C-acetyltransferase Acetyl-CoA C-acetyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.9 2.3.1.9] Full crystallographic information is available from [http:// | + | 1M3K is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zoogloea_ramigera Zoogloea ramigera] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Acetyl-CoA_C-acetyltransferase Acetyl-CoA C-acetyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.9 2.3.1.9] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1M3K OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Zoogloea ramigera]] | [[Category: Zoogloea ramigera]] | ||
[[Category: Kursula, P.]] | [[Category: Kursula, P.]] | ||
| - | [[Category: Lambeir, A | + | [[Category: Lambeir, A M.]] |
[[Category: Ojala, J.]] | [[Category: Ojala, J.]] | ||
| - | [[Category: Wierenga, R | + | [[Category: Wierenga, R K.]] |
[[Category: GOL]] | [[Category: GOL]] | ||
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: thiolase fold]] | [[Category: thiolase fold]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:51:05 2008'' |
Revision as of 11:51, 21 February 2008
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biosynthetic thiolase, inactive C89A mutant
Overview
Biosynthetic thiolase catalyzes the formation of acetoacetyl-CoA from two molecules of acetyl-CoA. This is a key step in the synthesis of many biological compounds, including steroid hormones and ketone bodies. The thiolase reaction involves two chemically distinct steps; during acyl transfer, an acetyl group is transferred from acetyl-CoA to Cys89, and in the Claisen condensation step, this acetyl group is further transferred to a second molecule of acetyl-CoA, generating acetoacetyl-CoA. Here, new crystallographic data for Zoogloea ramigera biosynthetic thiolase are presented, covering all intermediates of the thiolase catalytic cycle. The high-resolution structures indicate that the acetyl group goes through four conformations while being transferred from acetyl-CoA via the acetylated enzyme to acetoacetyl-CoA. This transfer is catalyzed in a rigid cavity lined by mostly hydrophobic side chains, in addition to the catalytic residues Cys89, His348, and Cys378. The structures highlight the importance of an oxyanion hole formed by a water molecule and His348 in stabilizing the negative charge on the thioester oxygen atom of acetyl-CoA at two different steps of the reaction cycle. Another oxyanion hole, composed of the main chain nitrogen atoms of Cys89 and Gly380, complements a negative charge of the thioester oxygen anion of the acetylated intermediate, stabilizing the tetrahedral transition state of the Claisen condensation step. The reactivity of the active site may be modulated by hydrogen bonding networks extending from the active site toward the back of the molecule.
About this Structure
1M3K is a Single protein structure of sequence from Zoogloea ramigera with and as ligands. Active as Acetyl-CoA C-acetyltransferase, with EC number 2.3.1.9 Full crystallographic information is available from OCA.
Reference
The catalytic cycle of biosynthetic thiolase: a conformational journey of an acetyl group through four binding modes and two oxyanion holes., Kursula P, Ojala J, Lambeir AM, Wierenga RK, Biochemistry. 2002 Dec 31;41(52):15543-56. PMID:12501183
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