The outer membrane (OM) of gram-negative bacteria is an asymmetric lipid bilayer that protects the cell from toxic molecules. Lipopolysaccharide (LPS) is an essential component of the OM in most gram-negative bacteria, and its structure and biosynthesis are well known. Nevertheless, the mechanisms of transport and assembly of this molecule in the OM are poorly understood. To date, the only proteins implicated in LPS transport are MsbA, responsible for LPS flipping across the inner membrane, and the Imp/RlpB complex, involved in LPS targeting to the OM. Here, we present evidence that two Escherichia coli essential genes, yhbN and yhbG, now renamed lptA and lptB, respectively, participate in LPS biogenesis. We show that mutants depleted of LptA and/or LptB not only produce an anomalous LPS form, but also are defective in LPS transport to the OM and accumulate de novo-synthesized LPS in a novel membrane fraction of intermediate density between the inner membrane (IM) and the OM. In addition, we show that LptA is located in the periplasm and that expression of the lptA-lptB operon is controlled by the extracytoplasmic σ factor RpoE. Based on these data, we propose that LptA and LptB are implicated in the transport of LPS from the IM to the OM of E. coli. Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Sperandeo, P., Cescutti, R., Villa, R., Di Benedetto, C., Candia, D., Polissi, A. (2007). Characterization of lptA and lptB, two essential genes implicated in lipopolysaccharide transport to the outer membrane of Escherichia coli. JOURNAL OF BACTERIOLOGY, 189(1), 244-253 [10.1128/JB.01126-06].

Characterization of lptA and lptB, two essential genes implicated in lipopolysaccharide transport to the outer membrane of Escherichia coli

POLISSI, ALESSANDRA
2007

Abstract

The outer membrane (OM) of gram-negative bacteria is an asymmetric lipid bilayer that protects the cell from toxic molecules. Lipopolysaccharide (LPS) is an essential component of the OM in most gram-negative bacteria, and its structure and biosynthesis are well known. Nevertheless, the mechanisms of transport and assembly of this molecule in the OM are poorly understood. To date, the only proteins implicated in LPS transport are MsbA, responsible for LPS flipping across the inner membrane, and the Imp/RlpB complex, involved in LPS targeting to the OM. Here, we present evidence that two Escherichia coli essential genes, yhbN and yhbG, now renamed lptA and lptB, respectively, participate in LPS biogenesis. We show that mutants depleted of LptA and/or LptB not only produce an anomalous LPS form, but also are defective in LPS transport to the OM and accumulate de novo-synthesized LPS in a novel membrane fraction of intermediate density between the inner membrane (IM) and the OM. In addition, we show that LptA is located in the periplasm and that expression of the lptA-lptB operon is controlled by the extracytoplasmic σ factor RpoE. Based on these data, we propose that LptA and LptB are implicated in the transport of LPS from the IM to the OM of E. coli. Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Articolo in rivista - Articolo scientifico
Lipopolisaccaride Microbiologia
English
244
253
Sperandeo, P., Cescutti, R., Villa, R., Di Benedetto, C., Candia, D., Polissi, A. (2007). Characterization of lptA and lptB, two essential genes implicated in lipopolysaccharide transport to the outer membrane of Escherichia coli. JOURNAL OF BACTERIOLOGY, 189(1), 244-253 [10.1128/JB.01126-06].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/14522
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