期刊
NATURE COMMUNICATIONS
卷 10, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/s41467-019-11977-1
关键词
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资金
- National Key Research and Development Program of China [2017YFA0504803, 2018YFA0507700]
- National Young Thousand Talents Program
- Sichuan Province Thousand Talents Program
- Fundamental Research Funds for the Central Universities [2018XZZX001-13]
- Zhejiang University [SJS201814]
- Wellcome Trust [WT106121MA]
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 LptB(2)FG powers the process through a yet unclarified mechanism. Here we report three high-resolution cryo-EM structures of LptB(2)FG alone and complexed with LptC (LptB(2)FGC), 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.
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