4HR7: Crystal Structure of Biotin Carboxyl Carrier Protein-biotin Carboxylase Complex From E.coli

Acetyl-coenzyme A (acetyl-CoA) carboxylase is a biotin-dependent, multifunctional enzyme that catalyzes the regulated step in fatty acid synthesis. The Escherichia coli enzyme is composed of a homodimeric biotin carboxylase (BC), biotinylated biotin carboxyl carrier protein (BCCP), and an alpha2beta2 heterotetrameric carboxyltransferase. This enzyme complex catalyzes two half-reactions to form malonyl-coenzyme A. BC and BCCP participate in the first half-reaction, whereas carboxyltransferase and BCCP are involved in the second. Three-dimensional structures have been reported for the individual subunits; however, the structural basis for how BCCP reacts with the carboxylase or transferase is unknown. Therefore, we report here the crystal structure of E. coli BCCP complexed with BC to a resolution of 2.49 A. The protein-protein complex shows a unique quaternary structure and two distinct interfaces for each BCCP monomer. These BCCP binding sites are unique compared to phylogenetically related biotin-dependent carboxylases and therefore provide novel targets for developing antibiotics against bacterial acetyl-CoA carboxylase.
PDB ID: 4HR7Download
MMDB ID: 108315
PDB Deposition Date: 2012/10/26
Updated in MMDB: 2013/05 
Experimental Method:
x-ray diffraction
Resolution: 2.5  Å
Source Organism:
Similar Structures:
Biological Unit for 4HR7: octameric; determined by author and by software (PISA)
Molecular Components in 4HR7
Label Count Molecule
Proteins (8 molecules)
Biotin Carboxylase
Molecule annotation
Biotin Carboxyl Carrier Protein of Acetyl-coa Carboxylase
Molecule annotation
Chemicals (13 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB