5M45

Structure of Acetone Carboxylase purified from Xanthobacter autotrophicus

Summary for 5M45

• Entry DOI: 10.2210/pdb5m45/pdb
• Descriptor: Acetone carboxylase alpha subunit, Acetone carboxylase beta subunit, Acetone carboxylase gamma subunit, ... (10 entities in total)
• Functional Keywords: carboxylation, ligase
• Biological source: Xanthobacter autotrophicus Py2; More
• Total number of polymer chains: 12
• Total formula weight: 744035.30

Authors

Kabasakal, B.V.,Wells, J.N.,Nwaobi, B.C.,Eilers, B.J.,Peters, J.W.,Murray, J.W. (deposition date: 2016-10-18, release date: 2017-08-09, Last modification date: 2024-01-17)

Primary citation

Mus, F.,Eilers, B.J.,Alleman, A.B.,Kabasakal, B.V.,Wells, J.N.,Murray, J.W.,Nocek, B.P.,DuBois, J.L.,Peters, J.W.
Structural Basis for the Mechanism of ATP-Dependent Acetone Carboxylation.
Sci Rep, 7:7234-7234, 2017

PubMed Abstract: Microorganisms use carboxylase enzymes to form new carbon-carbon bonds by introducing carbon dioxide gas (CO) or its hydrated form, bicarbonate (HCO), into target molecules. Acetone carboxylases (ACs) catalyze the conversion of substrates acetone and HCO to form the product acetoacetate. Many bicarbonate-incorporating carboxylases rely on the organic cofactor biotin for the activation of bicarbonate. ACs contain metal ions but not organic cofactors, and use ATP to activate substrates through phosphorylation. How the enzyme coordinates these phosphorylation events and new C-C bond formation in the absence of biotin has remained a mystery since these enzymes were discovered. The first structural rationale for acetone carboxylation is presented here, focusing on the 360 kDa (αβγ) heterohexameric AC from Xanthobacter autotrophicus in the ligand-free, AMP-bound, and acetate coordinated states. These structures suggest successive steps in a catalytic cycle revealing that AC undergoes large conformational changes coupled to substrate activation by ATP to perform C-C bond ligation at a distant Mn center. These results illustrate a new chemical strategy for the conversion of CO into biomass, a process of great significance to the global carbon cycle.

PubMed: 28775283
DOI: 10.1038/s41598-017-06973-8

Experimental method

X-RAY DIFFRACTION (1.87 Å)