TY - JOUR TI - A structural mechanism for bacterial autotransporter glycosylation by a dodecameric heptosyltransferase family AU - Yao, Qing AU - Lu, Qiuhe AU - Wan, Xiaobo AU - Song, Feng AU - Xu, Yue AU - Hu, Mo AU - Zamyatina, Alla AU - Liu, Xiaoyun AU - Huang, Niu AU - Zhu, Ping AU - Shao, Feng A2 - van der Donk, Wilfred VL - 3 PY - 2014 DA - 2014/10/13 SP - e03714 C1 - eLife 2014;3:e03714 DO - 10.7554/eLife.03714 UR - https://doi.org/10.7554/eLife.03714 AB - 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. KW - bacterial autotransporter KW - glycosyltransferase KW - bacterial pathogenesis KW - cryo-EM KW - enzyme complex KW - enzyme catalysis JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -