#1: ジャーナル: Elife / 年: 2014 タイトル: A structural mechanism for bacterial autotransporter glycosylation by a dodecameric heptosyltransferase family. 著者: Qing Yao / Qiuhe Lu / Xiaobo Wan / Feng Song / Yue Xu / Mo Hu / Alla Zamyatina / Xiaoyun Liu / Niu Huang / Ping Zhu / Feng Shao / 要旨: A large group of bacterial virulence autotransporters including AIDA-I from diffusely adhering E. coli (DAEC) and TibA from enterotoxigenic E. coli (ETEC) require hyperglycosylation for functioning. ...A large group of bacterial virulence autotransporters including AIDA-I from diffusely adhering E. coli (DAEC) and TibA from enterotoxigenic E. coli (ETEC) require hyperglycosylation for functioning. Here we demonstrate that TibC from ETEC harbors a heptosyltransferase activity on TibA and AIDA-I, defining a large family of bacterial autotransporter heptosyltransferases (BAHTs). The crystal structure of TibC reveals a characteristic ring-shape dodecamer. The protomer features an N-terminal β-barrel, a catalytic domain, a β-hairpin thumb, and a unique iron-finger motif. The iron-finger motif contributes to back-to-back dimerization; six dimers form the ring through β-hairpin thumb-mediated hand-in-hand contact. The structure of ADP-D-glycero-β-D-manno-heptose (ADP-D,D-heptose)-bound TibC reveals a sugar transfer mechanism and also the ligand stereoselectivity determinant. Electron-cryomicroscopy analyses uncover a TibC-TibA dodecamer/hexamer assembly with two enzyme molecules binding to one TibA substrate. The complex structure also highlights a high efficient hyperglycosylation of six autotransporter substrates simultaneously by the dodecamer enzyme complex.
開始モデル: SAD 解像度: 2.11→19.87 Å / Cor.coef. Fo:Fc: 0.958 / Cor.coef. Fo:Fc free: 0.941 / SU B: 5.778 / SU ML: 0.152 / 交差検証法: THROUGHOUT / σ(F): 0 / ESU R: 0.29 / ESU R Free: 0.213 / 立体化学のターゲット値: MAXIMUM LIKELIHOOD 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS U VALUES: REFINED INDIVIDUALLY
Rfactor
反射数
%反射
Selection details
Rfree
0.2476
1598
5.1 %
RANDOM
Rwork
0.2055
29958
-
-
obs
0.2076
31556
97.77 %
-
溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1.2 Å / 溶媒モデル: MASK