Centre National de la Recherche Scientifique (CNRS)
ATIP-Avenir
フランス
Agence Nationale de la Recherche (ANR)
ANR-18-CE11- 0006-01
フランス
Agence Nationale de la Recherche (ANR)
ANR-15-IDEX-02
フランス
引用
ジャーナル: Nat Commun / 年: 2022 タイトル: Structure of the human heparan sulfate polymerase complex EXT1-EXT2. 著者: Francisco Leisico / Juneina Omeiri / Christine Le Narvor / Joël Beaudouin / Michael Hons / Daphna Fenel / Guy Schoehn / Yohann Couté / David Bonnaffé / Rabia Sadir / Hugues Lortat-Jacob / Rebekka Wild / 要旨: Heparan sulfates are complex polysaccharides that mediate the interaction with a broad range of protein ligands at the cell surface. A key step in heparan sulfate biosynthesis is catalyzed by the bi- ...Heparan sulfates are complex polysaccharides that mediate the interaction with a broad range of protein ligands at the cell surface. A key step in heparan sulfate biosynthesis is catalyzed by the bi-functional glycosyltransferases EXT1 and EXT2, which generate the glycan backbone consisting of repeating N-acetylglucosamine and glucuronic acid units. The molecular mechanism of heparan sulfate chain polymerization remains, however, unknown. Here, we present the cryo-electron microscopy structure of human EXT1-EXT2, which reveals the formation of a tightly packed hetero-dimeric complex harboring four glycosyltransferase domains. A combination of in vitro and in cellulo mutational studies is used to dissect the functional role of the four catalytic sites. While EXT1 can catalyze both glycosyltransferase reactions, our results indicate that EXT2 might only have N-acetylglucosamine transferase activity. Our findings provide mechanistic insight into heparan sulfate chain elongation as a nonprocessive process and lay the foundation for future studies on EXT1-EXT2 function in health and disease.
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK IV
詳細
Purified EXT1-EXT2 complex at 0.4mg/mL was mixed with 1mM of UDP-GlcNAc, 1mM UDP-GlcA and 1mM MnCl2 and incubated 15 min on ice before applying 4 uL of the sample onto a glow discharged Quantifoil holey carbon grid (R1.2/1.3, 300 mesh, copper).
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
撮影
フィルム・検出器のモデル: GATAN K3 BIOQUANTUM (6k x 4k) 平均電子線量: 46.0 e/Å2
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: OTHER / 撮影モード: BRIGHT FIELD / 最大 デフォーカス(公称値): 3.0 µm / 最小 デフォーカス(公称値): 1.0 µm
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: INSILICO MODEL In silico モデル: Model of the hetero-dimeric EXT1-EXT2 complex predicted using the software AlphaFold2.
最終 再構成
解像度のタイプ: BY AUTHOR / 解像度: 2.8 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 使用した粒子像数: 286390