Paper Citing NAMD - Abstract
Yao, Qing; Lu, Qiuhe; Wan, Xiaobo; Song, Feng; Xu, Yue; Hu, Mo; Zamyatina, Alla; Liu, Xiaoyun; Huang, Niu; Zhu, Ping; Shao, Feng
A structural mechanism for bacterial autotransporter glycosylation by a dodecameric heptosyltransferase family
ELIFE, 3 Art. No. 03714, OCT 13 2014
A large group of bacterial virulence autotransporters including AIDA-I from diffusely adhering E. coli (DAEC) and TibA from enterotoxigenic E. coli (ETEC) require hyper-glycosylation 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). Crystal structure of TibC reveals a characteristic ring-shape dodecamer. The protomer features an N-terminal beta-barrel, a catalytic domain, a beta-hairpin thumb and a unique iron-finger motif The iron-finger motif contributes to back-to-back dimerization; six dimers form the ring through beta-hairpin thumb-mediated hand-in-hand contact. Structure of ADP-D, D-heptose-bound TibC reveals a sugar transfer mechanism and also the ligand stereoselectivity determinant. Cryo-EM 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.
