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Science. 2013 May 17;340(6134):837-41. doi: 10.1126/science.1235358.

Dual molecular signals mediate the bacterial response to outer-membrane stress.

Author information

1
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Abstract

In Gram-negative bacteria, outer-membrane integrity is essential for survival and is monitored by the σ(E) stress-response system, which initiates damage-repair pathways. One activating signal is unassembled outer-membrane proteins. Using biochemical and genetic experiments in Escherichia coli, we found that off-pathway intermediates in lipopolysaccharide transport and assembly provided an additional required signal. These distinct signals, arising from disruptions in the transport and assembly of the major outer-membrane components, jointly determined the rate of proteolytic destruction of a negative regulator of the σ(E) transcription factor, thereby modulating the expression of stress-response genes. This dual-signal system permits a rapid response to dysfunction in outer-membrane biogenesis, while buffering responses to transient fluctuations in individual components, and may represent a broad strategy for bacteria to monitor their interface with the environment.

PMID:
23687042
PMCID:
PMC3928677
DOI:
10.1126/science.1235358
[Indexed for MEDLINE]
Free PMC Article

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