6MIT

LptBFGC from Enterobacter cloacae

Summary for 6MIT

• Entry DOI: 10.2210/pdb6mit/pdb
• Descriptor: Lipopolysaccharide export system ATP-binding protein, Lipopolysaccharide export system protein LptC, LPS export ABC transporter permease LptF, ... (8 entities in total)
• Functional Keywords: lipopolysaccharide transport, abc-transporter, lipid transport
• Biological source: Enterobacter cloacae subsp. cloacae (strain ATCC 13047 / DSM 30054 / NBRC 13535 / NCDC 279-56); More
• Total number of polymer chains: 10
• Total formula weight: 313791.58

Authors

Owens, T.W.,Kahne, D.,Kruse, A.C. (deposition date: 2018-09-20, release date: 2019-03-27, Last modification date: 2023-10-11)

Primary citation

Owens, T.W.,Taylor, R.J.,Pahil, K.S.,Bertani, B.R.,Ruiz, N.,Kruse, A.C.,Kahne, D.
Structural basis of unidirectional export of lipopolysaccharide to the cell surface.
Nature, 567:550-553, 2019

PubMed Abstract: Gram-negative bacteria are surrounded by an inner cytoplasmic membrane and by an outer membrane, which serves as a protective barrier to limit entry of many antibiotics. The distinctive properties of the outer membrane are due to the presence of lipopolysaccharide. This large glycolipid, which contains numerous sugars, is made in the cytoplasm; a complex of proteins forms a membrane-to-membrane bridge that mediates transport of lipopolysaccharide from the inner membrane to the cell surface. The inner-membrane components of the protein bridge comprise an ATP-binding cassette transporter that powers transport, but how this transporter ensures unidirectional lipopolysaccharide movement across the bridge to the outer membrane is unknown. Here we describe two crystal structures of a five-component inner-membrane complex that contains all the proteins required to extract lipopolysaccharide from the membrane and pass it to the protein bridge. Analysis of these structures, combined with biochemical and genetic experiments, identifies the path of lipopolysaccharide entry into the cavity of the transporter and up to the bridge. We also identify a protein gate that must open to allow movement of substrate from the cavity onto the bridge. Lipopolysaccharide entry into the cavity is ATP-independent, but ATP is required for lipopolysaccharide movement past the gate and onto the bridge. Our findings explain how the inner-membrane transport complex controls efficient unidirectional transport of lipopolysaccharide against its concentration gradient.

PubMed: 30894747
DOI: 10.1038/s41586-019-1039-0

Experimental method

X-RAY DIFFRACTION (3.2 Å)