Signal integration by DegS and RseB governs the &#963; E-mediated envelope stress response in Escherichia coli.
In Escherichia coli, the σ(E) transcription factor monitors and maintains outer membrane (OM) integrity by activating genes required for assembly of its two key components, outer membrane proteins (OMPs) and lipopolysaccharide (LPS) and by transcribing small RNAs to down-regulate excess unassembled OMPs. σ(E) activity is governed by the rate of degradation of its membrane-spanning anti-σ factor, RseA. Importantly, the DegS protease can initiate RseA cleavage only when activated by binding to unassembled OMPs. The prevalent paradigm has been that the σ(E) response is controlled by the amount of activated DegS. Here we demonstrate that inactivation of a second negative regulator, the periplasmic protein RseB, is also required for σ(E) induction in vivo. Moreover, OMPs, previously known only to activate DegS, also generate a signal to antagonize RseB inhibition. This signal may be lipid related, as RseB is structurally similar to proteins that bind lipids. We propose that the use of an AND gate enables σ(E) to sense and integrate multivariate signals from the envelope.
Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA. rachnachaba@gmail.com
Rachna
R
Chaba
Benjamin M
BM
Alba
Monica S
MS
Guo
Jungsan
J
Sohn
Nidhi
N
Ahuja
Robert T
RT
Sauer
Carol A
CA
Gross
D001425:Bacterial Outer Membrane Proteins / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D015398:Signal Transduction
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C494790:RseB protein, E coli; C489349:degS protein, Escherichia coli
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