Saltar al contenido
Merck
  • Cryo-EM structures of lipopolysaccharide transporter LptB2FGC in lipopolysaccharide or AMP-PNP-bound states reveal its transport mechanism.

Cryo-EM structures of lipopolysaccharide transporter LptB2FGC in lipopolysaccharide or AMP-PNP-bound states reveal its transport mechanism.

Nature communications (2019-09-15)
Xiaodi Tang, Shenghai Chang, Qinghua Luo, Zhengyu Zhang, Wen Qiao, Caihuang Xu, Changbin Zhang, Yang Niu, Wenxian Yang, Ting Wang, Zhibo Zhang, Xiaofeng Zhu, Xiawei Wei, Changjiang Dong, Xing Zhang, Haohao Dong
RESUMEN

Lipopolysaccharides (LPS) of Gram-negative bacteria are critical for the defence against cytotoxic substances and must be transported from the inner membrane (IM) to the outer membrane (OM) through a bridge formed by seven membrane proteins (LptBFGCADE). The IM component LptB2FG powers the process through a yet unclarified mechanism. Here we report three high-resolution cryo-EM structures of LptB2FG alone and complexed with LptC (LptB2FGC), trapped in either the LPS- or AMP-PNP-bound state. The structures reveal conformational changes between these states and substrate binding with or without LptC. We identify two functional transmembrane arginine-containing loops interacting with the bound AMP-PNP and elucidate allosteric communications between the domains. AMP-PNP binding induces an inward rotation and shift of the transmembrane helices of LptFG and LptC to tighten the cavity, with the closure of two lateral gates, to eventually expel LPS into the bridge. Functional assays reveal the functionality of the LptF and LptG periplasmic domains. Our findings shed light on the LPS transport mechanism.

MATERIALES
Referencia del producto
Marca
Descripción del producto

Sigma-Aldrich
ANTI-FLAG® M2 monoclonal antibody produced in mouse, clone M2, purified immunoglobulin (Purified IgG1 subclass), buffered aqueous solution (10 mM sodium phosphate, 150 mM NaCl, pH 7.4, containing 0.02% sodium azide)
Sigma-Aldrich
Anti-c-Myc, clone 9E10, purified from hybridoma cell culture