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| - | [[Image:1f91.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1f91| PDB=1f91 | SCENE= }} | | {{STRUCTURE_1f91| PDB=1f91 | SCENE= }} |
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| - | '''BETA-KETOACYL-[ACYL-CARRIER-PROTEIN] SYNTHASE I IN COMPLEX WITH C10 FATTY ACID SUBSTRATE'''
| + | ===BETA-KETOACYL-[ACYL-CARRIER-PROTEIN] SYNTHASE I IN COMPLEX WITH C10 FATTY ACID SUBSTRATE=== |
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| - | ==Overview==
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| - | BACKGROUND: beta-ketoacyl-acyl carrier protein synthase (KAS) I is vital for the construction of the unsaturated fatty acid carbon skeletons characterizing E. coli membrane lipids. The new carbon-carbon bonds are created by KAS I in a Claisen condensation performed in a three-step enzymatic reaction. KAS I belongs to the thiolase fold enzymes, of which structures are known for five other enzymes. RESULTS: Structures of the catalytic Cys-Ser KAS I mutant with covalently bound C10 and C12 acyl substrates have been determined to 2.40 and 1.85 A resolution, respectively. The KAS I dimer is not changed by the formation of the complexes but reveals an asymmetric binding of the two substrates bound to the dimer. A detailed model is proposed for the catalysis of KAS I. Of the two histidines required for decarboxylation, one donates a hydrogen bond to the malonyl thioester oxo group, and the other abstracts a proton from the leaving group. CONCLUSIONS: The same mechanism is proposed for KAS II, which also has a Cys-His-His active site triad. Comparison to the active site architectures of other thiolase fold enzymes carrying out a decarboxylation step suggests that chalcone synthase and KAS III with Cys-His-Asn triads use another mechanism in which both the histidine and the asparagine interact with the thioester oxo group. The acyl binding pockets of KAS I and KAS II are so similar that they alone cannot provide the basis for their differences in substrate specificity.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_11286890}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 11286890 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_11286890}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Dimer]] | | [[Category: Dimer]] |
| | [[Category: Thiolase fold family]] | | [[Category: Thiolase fold family]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 16:02:57 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 02:53:34 2008'' |
Revision as of 23:53, 30 June 2008
Template:STRUCTURE 1f91
BETA-KETOACYL-[ACYL-CARRIER-PROTEIN] SYNTHASE I IN COMPLEX WITH C10 FATTY ACID SUBSTRATE
Template:ABSTRACT PUBMED 11286890
About this Structure
1F91 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structures of beta-ketoacyl-acyl carrier protein synthase I complexed with fatty acids elucidate its catalytic machinery., Olsen JG, Kadziola A, von Wettstein-Knowles P, Siggaard-Andersen M, Larsen S, Structure. 2001 Mar 7;9(3):233-43. PMID:11286890
Page seeded by OCA on Tue Jul 1 02:53:34 2008
