6S8H

Cryo-EM structure of LptB2FG in complex with LPS

Summary for 6S8H

• Entry DOI: 10.2210/pdb6s8h/pdb
• Related: 6S8G
• EMDB information: 10121 10122
• Descriptor: Lipopolysaccharide ABC transporter, ATP-binding protein LptB, Lipopolysaccharide export system permease protein LptF, Inner membrane protein yjgQ, ... (7 entities in total)
• Functional Keywords: lipopolysaccharide transporter, lps, lptb2fgc, lptb, lptbfg, outer membrane, gram-negative bacteria, abc transporter, inner membrane protein complex, transport protein
• Biological source: Shigella flexneri; More
• Total number of polymer chains: 4
• Total formula weight: 140294.84

Authors

Tang, X.D.,Chang, S.H.,Luo, Q.H.,Zhang, Z.Y.,Qiao, W.,Xu, C.H.,Zhang, C.B.,Niu, Y.,Yang, W.X.,Wang, T.,Zhang, Z.B.,Zhu, X.F.,Dong, C.J.,Zhang, X.,Dong, H.H. (deposition date: 2019-07-10, release date: 2019-09-25, Last modification date: 2024-05-22)

Primary citation

Tang, X.,Chang, S.,Luo, Q.,Zhang, Z.,Qiao, W.,Xu, C.,Zhang, C.,Niu, Y.,Yang, W.,Wang, T.,Zhang, Z.,Zhu, X.,Wei, X.,Dong, C.,Zhang, X.,Dong, H.
Cryo-EM structures of lipopolysaccharide transporter LptB2FGC in lipopolysaccharide or AMP-PNP-bound states reveal its transport mechanism.
Nat Commun, 10:4175-4175, 2019

PubMed Abstract: 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 LptBFG powers the process through a yet unclarified mechanism. Here we report three high-resolution cryo-EM structures of LptBFG alone and complexed with LptC (LptBFGC), 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.

PubMed: 31519889
DOI: 10.1038/s41467-019-11977-1

Experimental method

ELECTRON MICROSCOPY (3.7 Å)