5l9w
Crystal structure of the Apc core complex
Structural highlights
FunctionAPCD_AROAE Catalyzes the carboxylation of acetophenone to form 3-oxo-3-phenylpropanoate (benzoylacetate) in the anaerobic catabolism of ethylbenzene. Also carboxylates propiophenone at the same rate and 4-acetyl-pyridine at lower rates.[1] Publication Abstract from PubMedDegradation of the aromatic ketone acetophenone is initiated by its carboxylation to benzoylacetate catalyzed by acetophenone carboxylase (Apc) in a reaction dependent on the hydrolysis of two ATP to ADP and Pi. Apc is a large protein complex which dissociates during purification into a heterooctameric Apc(alphaalpha'betagamma)2 core complex of 482 kDa and Apcepsilon of 34 kDa. In this report, we present the X-ray structure of the Apc(alphaalpha'betagamma)2 core complex from Aromatoleum aromaticum at ca. 3 A resolution which reveals a unique modular architecture and serves as model of a new enzyme family. Apcbeta contains a novel domain fold composed of two beta-sheets in a barrel-like arrangement running into a bundle of eight short polyproline (type II)-like helical segments. Apcalpha and Apcalpha' possess ATP binding modules of the ASKHA superfamily integrated into their multidomain structures and presumably operate as ATP-dependent kinases for acetophenone and bicarbonate, respectively. Mechanistic aspects of the novel carboxylation reaction requiring massive structural rearrangements are discussed and criteria for specifically annotating the family members Apc, acetone carboxylase and hydantoinase are defined. Structure of the acetophenone carboxylase core complex: prototype of a new class of ATP-dependent carboxylases/hydrolases.,Weidenweber S, Schuhle K, Demmer U, Warkentin E, Ermler U, Heider J Sci Rep. 2017 Jan 5;7:39674. doi: 10.1038/srep39674. PMID:28054554[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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