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| {{STRUCTURE_1bdo| PDB=1bdo | SCENE= }} | | {{STRUCTURE_1bdo| PDB=1bdo | SCENE= }} |
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| '''STRUCTURE OF THE BIOTINYL DOMAIN OF ACETYL-COENZYME A CARBOXYLASE DETERMINED BY MAD PHASING'''
| | ===STRUCTURE OF THE BIOTINYL DOMAIN OF ACETYL-COENZYME A CARBOXYLASE DETERMINED BY MAD PHASING=== |
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| ==Overview==
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| BACKGROUND: Acetyl-coenzyme A carboxylase catalyzes the first committed step of fatty acid biosynthesis. Universally, this reaction involves three functional components all related to a carboxybiotinyl intermediate. A biotinyl domain shuttles its covalently attached biotin prosthetic group between the active sites of a biotin carboxylase and a carboxyl transferase. In Escherichia coli, the three components reside in separate subunits: a biotinyl domain is the functional portion of one of these, biotin carboxy carrier protein (BCCP). RESULTS: We have expressed natural and selenomethionyl (Se-met) BCCP from E. coli as biotinylated recombinant proteins, proteolyzed them with subtilisin Carlsberg to produce the biotinyl domains BCCP and Se-met BCCPsc, determined the crystal structure of Se-met BCCPsc using a modified version of the multiwavelength anomalous diffraction (MAD) phasing protocol, and refined the structure for the natural BCCPsc at 1.8 A resolution. The structure may be described as a capped beta sandwich with quasi-dyad symmetry. Each half contains a characteristic hammerhead motif. The biotinylated lysin is located at a hairpin beta turn which connects the two symmetric halves of the molecule, and its biotinyl group interacts with a non-symmetric protrusion from the core. CONCLUSIONS: This first crystal structure of a biotinyl domain helps to unravel the central role of such domains in reactions catalyzed by biotin-dependent carboxylases. The hammerhead structure observed twice in BCCPsc may be regarded as the basic structural motif of biotinyl and lipoyl domains of a superfamily of enzymes. The new MAD phasing techniques developed in the course of determining this structure enhance the power of the MAD method.
| | The line below this paragraph, {{ABSTRACT_PUBMED_8747466}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 8747466 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_8747466}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Ligase]] | | [[Category: Ligase]] |
| [[Category: Selenomethionine]] | | [[Category: Selenomethionine]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:22:51 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 18:54:52 2008'' |
