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Sci Rep. 2017 Aug 29;7(1):9715. doi: 10.1038/s41598-017-10136-0.

Interaction of lipopolysaccharides at intermolecular sites of the periplasmic Lpt transport assembly.

Author information

1
Université Grenoble Alpes, Institut de Biologie Structurale, 71 avenue des Martyrs - CS10090, 38044, Grenoble cedex 9, France. cedric.laguri@ibs.fr.
2
CEA, DSV, Institut de Biologie Structurale, 71 avenue des Martyrs - CS10090, 38044, Grenoble cedex 9, France. cedric.laguri@ibs.fr.
3
CNRS, Institut de Biologie Structurale, 71 avenue des Martyrs - CS10090, 38044, Grenoble cedex 9, France. cedric.laguri@ibs.fr.
4
University of Milano, Department of Pharmacological and Biomolecular Sciences, Via Balzaretti 9, Milano, Italy.
5
Université Grenoble Alpes, Institut de Biologie Structurale, 71 avenue des Martyrs - CS10090, 38044, Grenoble cedex 9, France.
6
CEA, DSV, Institut de Biologie Structurale, 71 avenue des Martyrs - CS10090, 38044, Grenoble cedex 9, France.
7
CNRS, Institut de Biologie Structurale, 71 avenue des Martyrs - CS10090, 38044, Grenoble cedex 9, France.
8
University of Naples Federico II, Department of Chemical Sciences, via cinthia 4, Napoli, Italy.
9
University of Milano, Department of Pharmacological and Biomolecular Sciences, Via Balzaretti 9, Milano, Italy. alessandra.polissi@unimi.it.

Abstract

Transport of lipopolysaccharides (LPS) to the surface of the outer membrane is essential for viability of Gram-negative bacteria. Periplasmic LptC and LptA proteins of the LPS transport system (Lpt) are responsible for LPS transfer between the Lpt inner and outer membrane complexes. Here, using a monomeric E. coli LptA mutant, we first show in vivo that a stable LptA oligomeric form is not strictly essential for bacteria. The LptC-LptA complex was characterized by a combination of SAXS and NMR methods and a low resolution model of the complex was determined. We were then able to observe interaction of LPS with LptC, the monomeric LptA mutant as well as with the LptC-LptA complex. A LptC-LPS complex was built based on NMR data in which the lipid moiety of the LPS is buried at the interface of the two β-jellyrolls of the LptC dimer. The selectivity of LPS for this intermolecular surface and the observation of such cavities at homo- or heteromolecular interfaces in LptC and LptA suggests that intermolecular sites are essential for binding LPS during its transport.

PMID:
28852068
PMCID:
PMC5575297
DOI:
10.1038/s41598-017-10136-0
[Indexed for MEDLINE]
Free PMC Article

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