2J9G

Crystal structure of Biotin carboxylase from E. coli in complex with AMPPNP and ADP

Summary for 2J9G

• Entry DOI: 10.2210/pdb2j9g/pdb
• Related: 1BNC 1DV1 1DV2 1K69 2C00 2GPS 2GPW 2VPQ 2VQD 2VR1
• Descriptor: BIOTIN CARBOXYLASE, MAGNESIUM ION, SULFATE ION, ... (6 entities in total)
• Functional Keywords: nucleotide-binding, fatty acid biosynthesis, atp-binding, lipid synthesis, biotin carboxylase, fas, adp, ligase, amppnp, biotin, bacterial
• Biological source: ESCHERICHIA COLI
• Total number of polymer chains: 2
• Total formula weight: 99947.45

Authors

Mochalkin, I. (deposition date: 2008-03-21, release date: 2008-09-09, Last modification date: 2023-12-13)

Primary citation

Mochalkin, I.,Miller, J.R.,Evdokimov, A.,Lightle, S.,Yan, C.,Stover, C.K.,Waldrop, G.L.
Structural Evidence for Substrate-Induced Synergism and Half-Sites Reactivity in Biotin Carboxylase.
Protein Sci., 17:1706-, 2008

PubMed Abstract: Bacterial acetyl-CoA carboxylase is a multifunctional biotin-dependent enzyme that consists of three separate proteins: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and carboxyltransferase (CT). Acetyl-CoA carboxylase is a potentially attractive target for novel antibiotics because it catalyzes the first committed step in fatty acid biosynthesis. In the first half-reaction, BC catalyzes the ATP-dependent carboxylation of BCCP. In the second half-reaction, the carboxyl group is transferred from carboxybiotinylated BCCP to acetyl-CoA to produce malonyl-CoA. A series of structures of BC from several bacteria crystallized in the presence of various ATP analogs is described that addresses three major questions concerning the catalytic mechanism. The structure of BC bound to AMPPNP and the two catalytically essential magnesium ions resolves inconsistencies between the kinetics of active-site BC mutants and previously reported BC structures. Another structure of AMPPNP bound to BC shows the polyphosphate chain folded back on itself, and not in the correct (i.e., extended) conformation for catalysis. This provides the first structural evidence for the hypothesis of substrate-induced synergism, which posits that ATP binds nonproductively to BC in the absence of biotin. The BC homodimer has been proposed to exhibit half-sites reactivity where the active sites alternate or "flip-flop" their catalytic cycles. A crystal structure of BC showed the ATP analog AMPPCF(2)P bound to one subunit while the other subunit was unliganded. The liganded subunit was in the closed or catalytic conformation while the unliganded subunit was in the open conformation. This provides the first structural evidence for half-sites reactivity in BC.

PubMed: 18725455
DOI: 10.1110/PS.035584.108

Experimental method

X-RAY DIFFRACTION (2.05 Å)