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Updated: Jun 23, 2026

Purification and Visualization of Lipopolysaccharide from Gram-negative Bacteria by Hot Aqueous-phenol Extraction
Published on: May 28, 2012
The lipopolysaccharide transport system of Gram-negative bacteria
Paola Sperandeo1, Gianni Dehò, Alessandra Polissi
1Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
Abstract:
The cell envelope of Gram-negative bacteria consists of two distinct membranes, the inner (IM) and the outer membrane (OM) separated by the periplasm. The OM contains in the outer leaflet the lipopolysaccharide (LPS), a complex lipid with important biological activities. In the host it elicits the innate immune response whereas in the bacterium it is responsible for the peculiar permeability barrier properties exhibited by the OM. The chemical structure of LPS and its biosynthetic pathways have been fully elucidated. By contrast only recently details of the transport and assembly of LPS into the OM have emerged. LPS is synthesized in the cytoplasm and at the inner leaflet of the IM and needs to cross two different compartments, the IM and the periplasm, to reach its final destination at the OM. This review focuses on recent studies that led to our present understanding of the protein machine implicated in LPS transport and in assembly at the cell surface.
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