A lipoprotein/β-barrel complex monitors lipopolysaccharide integrity transducing information across the outer membrane

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Abstract

Lipoprotein RcsF is the OM component of the Rcs envelope stress response. RcsF exists in complexes with β-barrel proteins (OMPs) allowing it to adopt a transmembrane orientation with a lipidated N-terminal domain on the cell surface and a periplasmic C-terminal domain. Here we report that mutations that remove BamE or alter a residue in the RcsF trans-lumen domain specifically prevent assembly of the interlocked complexes without inactivating either RcsF or the OMP. Using these mutations we demonstrate that these RcsF/OMP complexes are required for sensing OM outer leaflet stress. Using mutations that alter the positively charged surface-exposed domain, we show that RcsF monitors lateral interactions between lipopolysaccharide (LPS) molecules. When these interactions are disrupted by cationic antimicrobial peptides, or by the loss of negatively charged phosphate groups on the LPS molecule, this information is transduced to the RcsF C-terminal signaling domain located in the periplasm to activate the stress response.

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Anna Konovalova

Department of Molecular Biology, Princeton University, Princeton, United States

Competing interests
The authors declare that no competing interests exist.
Angela M Mitchell

Department of Molecular Biology, Princeton University, Princeton, United States

Competing interests
The authors declare that no competing interests exist.
Thomas J Silhavy

Department of Molecular Biology, Princeton University, Princeton, United States

For correspondence
tsilhavy@princeton.edu

Competing interests
The authors declare that no competing interests exist.

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