ジャーナル: Nature / 年: 2018 タイトル: Structural basis for regulation of human acetyl-CoA carboxylase. 著者: Moritz Hunkeler / Anna Hagmann / Edward Stuttfeld / Mohamed Chami / Yakir Guri / Henning Stahlberg / Timm Maier / 要旨: Acetyl-CoA carboxylase catalyses the ATP-dependent carboxylation of acetyl-CoA, a rate-limiting step in fatty acid biosynthesis. Eukaryotic acetyl-CoA carboxylases are large, homodimeric multienzymes. ...Acetyl-CoA carboxylase catalyses the ATP-dependent carboxylation of acetyl-CoA, a rate-limiting step in fatty acid biosynthesis. Eukaryotic acetyl-CoA carboxylases are large, homodimeric multienzymes. Human acetyl-CoA carboxylase occurs in two isoforms: the metabolic, cytosolic ACC1, and ACC2, which is anchored to the outer mitochondrial membrane and controls fatty acid β-oxidation. ACC1 is regulated by a complex interplay of phosphorylation, binding of allosteric regulators and protein-protein interactions, which is further linked to filament formation. These filaments were discovered in vitro and in vivo 50 years ago, but the structural basis of ACC1 polymerization and regulation remains unknown. Here, we identify distinct activated and inhibited ACC1 filament forms. We obtained cryo-electron microscopy structures of an activated filament that is allosterically induced by citrate (ACC-citrate), and an inactivated filament form that results from binding of the BRCT domains of the breast cancer type 1 susceptibility protein (BRCA1). While non-polymeric ACC1 is highly dynamic, filament formation locks ACC1 into different catalytically competent or incompetent conformational states. This unique mechanism of enzyme regulation via large-scale conformational changes observed in ACC1 has potential uses in engineering of switchable biosynthetic systems. Dissecting the regulation of acetyl-CoA carboxylase opens new paths towards counteracting upregulation of fatty acid biosynthesis in disease.
フィルム・検出器のモデル: GATAN K2 SUMMIT (4k x 4k) 平均電子線量: 80.0 e/Å2 詳細: Collected in movie-mode with total dose of 80 e-/A2 for a total of 80 frames. Frames 3-22 were used for final reconstruction.
電子線
加速電圧: 300 kV / 電子線源: FIELD EMISSION GUN
電子光学系
照射モード: FLOOD BEAM / 撮影モード: BRIGHT FIELD
実験機器
モデル: Titan Krios / 画像提供: FEI Company
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画像解析
初期モデル
モデルのタイプ: OTHER 詳細: Initial model was generated form 2D class averages using e2initialmodel.py in EMAN2