2ix4: Difference between revisions
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==Overview== | ==Overview== | ||
Two distinct ways of organizing fatty acid biosynthesis exist: the | Two distinct ways of organizing fatty acid biosynthesis exist: the multifunctional type I fatty acid synthase (FAS) of mammals, fungi, and lower eukaryotes with activities residing on one or two polypeptides; and the dissociated type II FAS of prokaryotes, plastids, and mitochondria with individual activities encoded by discrete genes. The beta-ketoacyl [ACP] synthase (KAS) moiety of the mitochondrial FAS (mtKAS) is targeted by the antibiotic cerulenin and possibly by the other antibiotics inhibiting prokaryotic KASes: thiolactomycin, platensimycin, and the alpha-methylene butyrolactone, C75. The high degree of structural similarity between mitochondrial and prokaryotic KASes complicates development of novel antibiotics targeting prokaryotic KAS without affecting KAS domains of cytoplasmic FAS. KASes catalyze the C(2) fatty acid elongation reaction using either a Cys-His-His or Cys-His-Asn catalytic triad. Three KASes with different substrate specificities participate in synthesis of the C(16) and C(18) products of prokaryotic FAS. By comparison, mtKAS carries out all elongation reactions in the mitochondria. We present the X-ray crystal structures of the Cys-His-His-containing human mtKAS and its hexanoyl complex plus the hexanoyl complex of the plant mtKAS from Arabidopsis thaliana. The structures explain (1) the bimodal (C(6) and C(10)-C(12)) substrate preferences leading to the C(8) lipoic acid precursor and long chains for the membranes, respectively, and (2) the low cerulenin sensitivity of the human enzyme; and (3) reveal two different potential acyl-binding-pocket extensions. Rearrangements taking place in the active site, including subtle changes in the water network, indicate a change in cooperativity of the active-site histidines upon primer binding. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Beta-ketoacyl-acyl-carrier-protein synthase I]] | [[Category: Beta-ketoacyl-acyl-carrier-protein synthase I]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Christensen, C | [[Category: Christensen, C E.]] | ||
[[Category: Henriksen, A.]] | [[Category: Henriksen, A.]] | ||
[[Category: Kragelund, B.]] | [[Category: Kragelund, B.]] | ||
[[Category: Wettstein-Knowles, P | [[Category: Wettstein-Knowles, P Von.]] | ||
[[Category: 6NA]] | [[Category: 6NA]] | ||
[[Category: K]] | [[Category: K]] | ||
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[[Category: transit peptide]] | [[Category: transit peptide]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:56:54 2008'' | ||
Revision as of 18:56, 21 February 2008
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ARABIDOPSIS THALIANA MITOCHONDRIAL BETA-KETOACYL ACP SYNTHASE HEXANOIC ACID COMPLEX
OverviewOverview
Two distinct ways of organizing fatty acid biosynthesis exist: the multifunctional type I fatty acid synthase (FAS) of mammals, fungi, and lower eukaryotes with activities residing on one or two polypeptides; and the dissociated type II FAS of prokaryotes, plastids, and mitochondria with individual activities encoded by discrete genes. The beta-ketoacyl [ACP] synthase (KAS) moiety of the mitochondrial FAS (mtKAS) is targeted by the antibiotic cerulenin and possibly by the other antibiotics inhibiting prokaryotic KASes: thiolactomycin, platensimycin, and the alpha-methylene butyrolactone, C75. The high degree of structural similarity between mitochondrial and prokaryotic KASes complicates development of novel antibiotics targeting prokaryotic KAS without affecting KAS domains of cytoplasmic FAS. KASes catalyze the C(2) fatty acid elongation reaction using either a Cys-His-His or Cys-His-Asn catalytic triad. Three KASes with different substrate specificities participate in synthesis of the C(16) and C(18) products of prokaryotic FAS. By comparison, mtKAS carries out all elongation reactions in the mitochondria. We present the X-ray crystal structures of the Cys-His-His-containing human mtKAS and its hexanoyl complex plus the hexanoyl complex of the plant mtKAS from Arabidopsis thaliana. The structures explain (1) the bimodal (C(6) and C(10)-C(12)) substrate preferences leading to the C(8) lipoic acid precursor and long chains for the membranes, respectively, and (2) the low cerulenin sensitivity of the human enzyme; and (3) reveal two different potential acyl-binding-pocket extensions. Rearrangements taking place in the active site, including subtle changes in the water network, indicate a change in cooperativity of the active-site histidines upon primer binding.
About this StructureAbout this Structure
2IX4 is a Single protein structure of sequence from Arabidopsis thaliana with and as ligands. Active as Beta-ketoacyl-acyl-carrier-protein synthase I, with EC number 2.3.1.41 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Structure of the human beta-ketoacyl [ACP] synthase from the mitochondrial type II fatty acid synthase., Christensen CE, Kragelund BB, von Wettstein-Knowles P, Henriksen A, Protein Sci. 2007 Feb;16(2):261-72. PMID:17242430
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OCA- Pages with broken file links
- Arabidopsis thaliana
- Beta-ketoacyl-acyl-carrier-protein synthase I
- Single protein
- Christensen, C E.
- Henriksen, A.
- Kragelund, B.
- Wettstein-Knowles, P Von.
- 6NA
- K
- Acyl complex
- Acyltransferase
- Beta-ketoacyl-(acyl carrier protein) synthase
- Condensing enzyme
- Fatty acid biosynthesis
- Fatty acid elongation
- Lipid metabolism
- Lipid synthesis
- Mitochondrion
- Synthase
- Transferase
- Transit peptide