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==Overview==
==Overview==
In the biosynthesis of fatty acids, the beta-ketoacyl-acyl carrier protein, (ACP) synthases catalyze chain elongation by the addition of two-carbon, units derived from malonyl-ACP to an acyl group bound to either ACP or, CoA. The crystal structure of beta-ketoacyl synthase II from Escherichia, coli has been determined with the multiple isomorphous replacement method, and refined at 2.4 A resolution. The subunit consists of two mixed, five-stranded beta-sheets surrounded by alpha-helices. The two sheets are, packed against each other in such a way that the fold can be described as, consisting of five layers, alpha-beta-alpha-beta-alpha. The enzyme is a, homodimer, and the subunits are related by a crystallographic 2-fold axis., The two active sites are located near the dimer interface but are, approximately 25 A apart. The proposed nucleophile in the reaction, Cys163, is located at the bottom of a mainly hydrophobic pocket which is, also lined with several conserved polar residues. In spite of very low, overall sequence homology, the structure of beta-ketoacyl synthase is, similar to that of thiolase, an enzyme involved in the beta-oxidation, pathway, indicating that both enzymes might have a common ancestor.
In the biosynthesis of fatty acids, the beta-ketoacyl-acyl carrier protein (ACP) synthases catalyze chain elongation by the addition of two-carbon units derived from malonyl-ACP to an acyl group bound to either ACP or CoA. The crystal structure of beta-ketoacyl synthase II from Escherichia coli has been determined with the multiple isomorphous replacement method and refined at 2.4 A resolution. The subunit consists of two mixed five-stranded beta-sheets surrounded by alpha-helices. The two sheets are packed against each other in such a way that the fold can be described as consisting of five layers, alpha-beta-alpha-beta-alpha. The enzyme is a homodimer, and the subunits are related by a crystallographic 2-fold axis. The two active sites are located near the dimer interface but are approximately 25 A apart. The proposed nucleophile in the reaction, Cys163, is located at the bottom of a mainly hydrophobic pocket which is also lined with several conserved polar residues. In spite of very low overall sequence homology, the structure of beta-ketoacyl synthase is similar to that of thiolase, an enzyme involved in the beta-oxidation pathway, indicating that both enzymes might have a common ancestor.


==About this Structure==
==About this Structure==
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[[Category: lipid metabolism]]
[[Category: lipid metabolism]]


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Revision as of 11:32, 21 February 2008

File:1kas.jpg


1kas, resolution 2.4Å

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BETA-KETOACYL-ACP SYNTHASE II FROM ESCHERICHIA COLI

Overview

In the biosynthesis of fatty acids, the beta-ketoacyl-acyl carrier protein (ACP) synthases catalyze chain elongation by the addition of two-carbon units derived from malonyl-ACP to an acyl group bound to either ACP or CoA. The crystal structure of beta-ketoacyl synthase II from Escherichia coli has been determined with the multiple isomorphous replacement method and refined at 2.4 A resolution. The subunit consists of two mixed five-stranded beta-sheets surrounded by alpha-helices. The two sheets are packed against each other in such a way that the fold can be described as consisting of five layers, alpha-beta-alpha-beta-alpha. The enzyme is a homodimer, and the subunits are related by a crystallographic 2-fold axis. The two active sites are located near the dimer interface but are approximately 25 A apart. The proposed nucleophile in the reaction, Cys163, is located at the bottom of a mainly hydrophobic pocket which is also lined with several conserved polar residues. In spite of very low overall sequence homology, the structure of beta-ketoacyl synthase is similar to that of thiolase, an enzyme involved in the beta-oxidation pathway, indicating that both enzymes might have a common ancestor.

About this Structure

1KAS is a Single protein structure of sequence from Escherichia coli. The following page contains interesting information on the relation of 1KAS with [Fatty Acid Synthase]. Active as Beta-ketoacyl-acyl-carrier-protein synthase I, with EC number 2.3.1.41 Known structural/functional Site: ACT. Full crystallographic information is available from OCA.

Reference

Crystal structure of beta-ketoacyl-acyl carrier protein synthase II from E.coli reveals the molecular architecture of condensing enzymes., Huang W, Jia J, Edwards P, Dehesh K, Schneider G, Lindqvist Y, EMBO J. 1998 Mar 2;17(5):1183-91. PMID:9482715

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