Crystal Structure of the alpha6beta6 Holoenzyme of propionyl-coenzyme A Carboxylase

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Nature

DOI:https://doi.org/10.1038/nature09302· OSTI ID:1019625

Huang, C; Sadre-Bazzaz, K; Shen, Y; Deng, B; Zhou, Z; Tong, L

Propionyl-coenzyme A carboxylase (PCC), a mitochondrial biotin-dependent enzyme, is essential for the catabolism of the amino acids Thr, Val, Ile and Met, cholesterol and fatty acids with an odd number of carbon atoms. Deficiencies in PCC activity in humans are linked to the disease propionic acidaemia, an autosomal recessive disorder that can be fatal in infants. The holoenzyme of PCC is an {alpha}{sub 6}{beta}{sub 6} dodecamer, with a molecular mass of 750 kDa. The {alpha}-subunit contains the biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) domains, whereas the {beta}-subunit supplies the carboxyltransferase (CT) activity. Here we report the crystal structure at 3.2-{angstrom} resolution of a bacterial PCC {alpha}{sub 6}{beta}{sub 6} holoenzyme as well as cryo-electron microscopy (cryo-EM) reconstruction at 15-{angstrom} resolution demonstrating a similar structure for human PCC. The structure defines the overall architecture of PCC and reveals unexpectedly that the {alpha}-subunits are arranged as monomers in the holoenzyme, decorating a central {beta}{sub 6} hexamer. A hitherto unrecognized domain in the {alpha}-subunit, formed by residues between the BC and BCCP domains, is crucial for interactions with the {beta}-subunit. We have named it the BT domain. The structure reveals for the first time the relative positions of the BC and CT active sites in the holoenzyme. They are separated by approximately 55 {angstrom}, indicating that the entire BCCP domain must translocate during catalysis. The BCCP domain is located in the active site of the {beta}-subunit in the current structure, providing insight for its involvement in the CT reaction. The structural information establishes a molecular basis for understanding the large collection of disease-causing mutations in PCC and is relevant for the holoenzymes of other biotin-dependent carboxylases, including 3-methylcrotonyl-CoA carboxylase (MCC) and eukaryotic acetyl-CoA carboxylase (ACC).

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1019625
• Report Number(s): BNL--95470-2011-JA
• Journal Information: Nature, Journal Name: Nature Journal Issue: 7309 Vol. 466; ISSN 0028-0836
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
AMINO ACIDS
ARCHITECTURE
ATOMS
BIOCHEMISTRY
BIOLOGY
BIOTIN
CARBON
CARBOXYLASE
CARBOXYLIC ACIDS
CATABOLISM
CATALYSIS
CHOLESTEROL
CRYSTAL STRUCTURE
DISEASES
MICROSCOPY
MONOMERS
MUTATIONS
PROTEINS
RESIDUES
RESOLUTION
national synchrotron light source