1BNC

THREE-DIMENSIONAL STRUCTURE OF THE BIOTIN CARBOXYLASE SUBUNIT OF ACETYL-COA CARBOXYLASE

Summary for 1BNC

• Entry DOI: 10.2210/pdb1bnc/pdb
• Descriptor: BIOTIN CARBOXYLASE, PHOSPHATE ION (3 entities in total)
• Functional Keywords: fatty acid biosynthesis
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 98963.25

Authors

Waldrop, G.,Rayment, I.,Holden, H.M. (deposition date: 1994-07-06, release date: 1995-08-30, Last modification date: 2024-02-07)

Primary citation

Waldrop, G.L.,Rayment, I.,Holden, H.M.
Three-dimensional structure of the biotin carboxylase subunit of acetyl-CoA carboxylase.
Biochemistry, 33:10249-10256, 1994

PubMed Abstract: Acetyl-CoA carboxylase is found in all animals, plants, and bacteria and catalyzes the first committed step in fatty acid synthesis. It is a multicomponent enzyme containing a biotin carboxylase activity, a biotin carboxyl carrier protein, and a carboxyltransferase functionality. Here we report the X-ray structure of the biotin carboxylase component from Escherichia coli determined to 2.4-A resolution. The structure was solved by a combination of multiple isomorphous replacement and electron density modification procedures. The overall fold of the molecule may be described in terms of three structural domains. The N-terminal region, formed by Met 1-Ile 103, adopts a dinucleotide binding motif with five strands of parallel beta-sheet flanked on either side by alpha-helices. The "B-domain" extends from the main body of the subunit where it folds into two alpha-helical regions and three strands of beta-sheet. Following the excursion into the B-domain, the polypeptide chain folds back into the body of the protein where it forms an eight-stranded antiparallel beta-sheet. In addition to this major secondary structural element, the C-terminal domain also contains a smaller three-stranded antiparallel beta-sheet and seven alpha-helices. The active site of the enzyme has been identified tentatively by a difference Fourier map calculated between X-ray data from the native crystals and from crystals soaked in a Ag+/biotin complex. Those amino acid residues believed to form part of the active site pocket include His 209-Glu 211, His 236-Glu 241, Glu 276, Ile 287-Glu 296, and Arg 338.2+ represents the first X-ray model of a biotin-dependent carboxylase.

PubMed: 7915138
DOI: 10.1021/bi00200a004

Experimental method

X-RAY DIFFRACTION (2.4 Å)