PDBsum entry 6s8h

Transport protein

PDB id: 6s8h

Contents

Protein chains

239 a.a.

239 a.a.

243 a.a.

Ligands

LMN ×2

JSG

DCQ ×2

LMT ×2

PDB id:

6s8h

Name:

Transport protein

Title:

Cryo-em structure of lptb2fg in complex with lps

Structure:

Lipopolysaccharide abc transporter, atp-binding protein lptb. Chain: a, b. Engineered: yes. Lipopolysaccharide export system permease protein lptf. Chain: f. Engineered: yes. Inner membrane protein yjgq. Chain: g.

Source:

Shigella flexneri. Organism_taxid: 623. Gene: sgf_01136. Expressed in: escherichia coli. Expression_system_taxid: 562. Gene: lptf, sf4228, s4489. Gene: yjgq, s4488, cqa91_25110, nctc9783_00309, samea3710568_03584. Expression_system_taxid: 562

Authors:

X.D.Tang,S.H.Chang,Q.H.Luo,Z.Y.Zhang,W.Qiao,C.H.Xu,C.B.Zhang,Y.Niu, W.X.Yang,T.Wang,Z.B.Zhang,X.F.Zhu,C.J.Dong,X.Zhang,H.H.Dong

Key ref:

X.Tang et al. (2019). Cryo-EM structures of lipopolysaccharide transporter LptB₂FGC in lipopolysaccharide or AMP-PNP-bound states reveal its transport mechanism. Nat Commun, 10, 4175. PubMed id: 31519889 DOI: 10.1038/s41467-019-11977-1

Date:

10-Jul-19 Release date: 25-Sep-19

Protein chains

P0A9V4  (LPTB_SHIFL) -  Lipopolysaccharide export system ATP-binding protein LptB from Shigella flexneri

Seq: 241 a.a.

Struc: 239 a.a.

Protein chain

P0AFA1  (LPTF_SHIFL) -  Lipopolysaccharide export system permease protein LptF from Shigella flexneri

Seq: 366 a.a.

Struc: 239 a.a.*

Protein chain

A0A0H2V3J7  (A0A0H2V3J7_SHIFL) -  LPS export ABC transporter permease LptG from Shigella flexneri

Seq: 360 a.a.

Struc: 243 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class 1: Chains A, B: E.C.7.5.2.- - ?????
• Enzyme class 2: Chains F, G: E.C.?

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

DOI no: 10.1038/s41467-019-11977-1

Nat Commun 10:4175 (2019)

PubMed id: 31519889

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

X.Tang, S.Chang, Q.Luo, Z.Zhang, W.Qiao, C.Xu, C.Zhang, Y.Niu, W.Yang, T.Wang, Z.Zhang, X.Zhu, X.Wei, C.Dong, X.Zhang, H.Dong.

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 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.