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Science. 2018 Feb 16;359(6377):798-801. doi: 10.1126/science.aar1886.

Lipopolysaccharide is transported to the cell surface by a membrane-to-membrane protein bridge.

Author information

1
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
2
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
3
FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
4
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
5
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. kahne@chemistry.harvard.edu.
6
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.

Abstract

Gram-negative bacteria have an outer membrane that serves as a barrier to noxious agents in the environment. This protective function is dependent on lipopolysaccharide, a large glycolipid located in the outer leaflet of the outer membrane. Lipopolysaccharide is synthesized at the cytoplasmic membrane and must be transported to the cell surface. To understand this transport process, we reconstituted membrane-to-membrane movement of lipopolysaccharide by incorporating purified inner and outer membrane transport complexes into separate proteoliposomes. Transport involved stable association between the inner and outer membrane proteoliposomes. Our results support a model in which lipopolysaccharide molecules are pushed one after the other in a PEZ dispenser-like manner across a protein bridge that connects the inner and outer membranes.

PMID:
29449493
PMCID:
PMC5858563
[Available on 2019-02-16]
DOI:
10.1126/science.aar1886
[Indexed for MEDLINE]

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