Reversal of the δdegp phenotypes by a novel rpoE allele of Escherichia coli

Owen P. Leiser, Emily S. Charlson, Henri Gerken, Rajeev Misra

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

RseA sequesters RpoE (σ E) to the inner membrane of Escherichia coli when envelope stress is low. Elevated envelope stress triggers RseA cleavage by the sequential action of two membrane proteases, DegS and RseP, releasing σ E to activate an envelope stress reducing pathway. Revertants of a ΔdegP ΔbamB strain, which fails to grow at 37°C due to high envelope stress, harbored mutations in the rseA and rpoE genes. Null and missense rseA mutations constitutively hyper-activated the σ E regulon and significantly reduced the major outer membrane protein (OMP) levels. In contrast, a novel rpoE allele, rpoE3, resulting from the partial duplication of the rpoE gene, increased σ E levels greater than that seen in the rseA mutant background but did not reduce OMP levels. A σ E-dependent RybB::LacZ construct showed only a weak activation of the σ E pathway by rpoE3. Despite this, rpoE3 fully reversed the growth and envelope vesiculation phenotypes of ΔdegP. Interestingly, rpoE3 also brought down the modestly activated Cpx envelope stress pathway in the ΔdegP strain to the wild type level, showing the complementary nature of the σ E and Cpx pathways. Through employing a labile mutant periplasmic protein, AcrA L222Q, it was determined that the rpoE3 mutation overcomes the ΔdegP phenotypes, in part, by activating a σ E-dependent proteolytic pathway. Our data suggest that a reduction in the OMP levels is not intrinsic to the σ E-mediated mechanism of lowering envelope stress. They also suggest that under extreme envelope stress, a tight homeostasis loop between RseA and σ E may partly be responsible for cell death, and this loop can be broken by mutations that either lower RseA activity or increase σ E levels.

Original languageEnglish (US)
Article numbere33979
JournalPLoS One
Volume7
Issue number3
DOIs
StatePublished - Mar 16 2012

Fingerprint

outer membrane proteins
Escherichia coli
Membrane Proteins
Alleles
alleles
Phenotype
mutation
phenotype
Mutation
Periplasmic Proteins
Regulon
regulon
mutants
missense mutation
Gene Duplication
Membranes
Missense Mutation
Mutant Proteins
gene duplication
cell death

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Reversal of the δdegp phenotypes by a novel rpoE allele of Escherichia coli. / Leiser, Owen P.; Charlson, Emily S.; Gerken, Henri; Misra, Rajeev.

In: PLoS One, Vol. 7, No. 3, e33979, 16.03.2012.

Research output: Contribution to journalArticle

Leiser, Owen P. ; Charlson, Emily S. ; Gerken, Henri ; Misra, Rajeev. / Reversal of the δdegp phenotypes by a novel rpoE allele of Escherichia coli. In: PLoS One. 2012 ; Vol. 7, No. 3.
@article{98da074d838045c9bff41e5c4665cb80,
title = "Reversal of the δdegp phenotypes by a novel rpoE allele of Escherichia coli",
abstract = "RseA sequesters RpoE (σ E) to the inner membrane of Escherichia coli when envelope stress is low. Elevated envelope stress triggers RseA cleavage by the sequential action of two membrane proteases, DegS and RseP, releasing σ E to activate an envelope stress reducing pathway. Revertants of a ΔdegP ΔbamB strain, which fails to grow at 37°C due to high envelope stress, harbored mutations in the rseA and rpoE genes. Null and missense rseA mutations constitutively hyper-activated the σ E regulon and significantly reduced the major outer membrane protein (OMP) levels. In contrast, a novel rpoE allele, rpoE3, resulting from the partial duplication of the rpoE gene, increased σ E levels greater than that seen in the rseA mutant background but did not reduce OMP levels. A σ E-dependent RybB::LacZ construct showed only a weak activation of the σ E pathway by rpoE3. Despite this, rpoE3 fully reversed the growth and envelope vesiculation phenotypes of ΔdegP. Interestingly, rpoE3 also brought down the modestly activated Cpx envelope stress pathway in the ΔdegP strain to the wild type level, showing the complementary nature of the σ E and Cpx pathways. Through employing a labile mutant periplasmic protein, AcrA L222Q, it was determined that the rpoE3 mutation overcomes the ΔdegP phenotypes, in part, by activating a σ E-dependent proteolytic pathway. Our data suggest that a reduction in the OMP levels is not intrinsic to the σ E-mediated mechanism of lowering envelope stress. They also suggest that under extreme envelope stress, a tight homeostasis loop between RseA and σ E may partly be responsible for cell death, and this loop can be broken by mutations that either lower RseA activity or increase σ E levels.",
author = "Leiser, {Owen P.} and Charlson, {Emily S.} and Henri Gerken and Rajeev Misra",
year = "2012",
month = "3",
day = "16",
doi = "10.1371/journal.pone.0033979",
language = "English (US)",
volume = "7",
journal = "PLoS One",
issn = "1932-6203",
publisher = "Public Library of Science",
number = "3",

}

TY - JOUR

T1 - Reversal of the δdegp phenotypes by a novel rpoE allele of Escherichia coli

AU - Leiser, Owen P.

AU - Charlson, Emily S.

AU - Gerken, Henri

AU - Misra, Rajeev

PY - 2012/3/16

Y1 - 2012/3/16

N2 - RseA sequesters RpoE (σ E) to the inner membrane of Escherichia coli when envelope stress is low. Elevated envelope stress triggers RseA cleavage by the sequential action of two membrane proteases, DegS and RseP, releasing σ E to activate an envelope stress reducing pathway. Revertants of a ΔdegP ΔbamB strain, which fails to grow at 37°C due to high envelope stress, harbored mutations in the rseA and rpoE genes. Null and missense rseA mutations constitutively hyper-activated the σ E regulon and significantly reduced the major outer membrane protein (OMP) levels. In contrast, a novel rpoE allele, rpoE3, resulting from the partial duplication of the rpoE gene, increased σ E levels greater than that seen in the rseA mutant background but did not reduce OMP levels. A σ E-dependent RybB::LacZ construct showed only a weak activation of the σ E pathway by rpoE3. Despite this, rpoE3 fully reversed the growth and envelope vesiculation phenotypes of ΔdegP. Interestingly, rpoE3 also brought down the modestly activated Cpx envelope stress pathway in the ΔdegP strain to the wild type level, showing the complementary nature of the σ E and Cpx pathways. Through employing a labile mutant periplasmic protein, AcrA L222Q, it was determined that the rpoE3 mutation overcomes the ΔdegP phenotypes, in part, by activating a σ E-dependent proteolytic pathway. Our data suggest that a reduction in the OMP levels is not intrinsic to the σ E-mediated mechanism of lowering envelope stress. They also suggest that under extreme envelope stress, a tight homeostasis loop between RseA and σ E may partly be responsible for cell death, and this loop can be broken by mutations that either lower RseA activity or increase σ E levels.

AB - RseA sequesters RpoE (σ E) to the inner membrane of Escherichia coli when envelope stress is low. Elevated envelope stress triggers RseA cleavage by the sequential action of two membrane proteases, DegS and RseP, releasing σ E to activate an envelope stress reducing pathway. Revertants of a ΔdegP ΔbamB strain, which fails to grow at 37°C due to high envelope stress, harbored mutations in the rseA and rpoE genes. Null and missense rseA mutations constitutively hyper-activated the σ E regulon and significantly reduced the major outer membrane protein (OMP) levels. In contrast, a novel rpoE allele, rpoE3, resulting from the partial duplication of the rpoE gene, increased σ E levels greater than that seen in the rseA mutant background but did not reduce OMP levels. A σ E-dependent RybB::LacZ construct showed only a weak activation of the σ E pathway by rpoE3. Despite this, rpoE3 fully reversed the growth and envelope vesiculation phenotypes of ΔdegP. Interestingly, rpoE3 also brought down the modestly activated Cpx envelope stress pathway in the ΔdegP strain to the wild type level, showing the complementary nature of the σ E and Cpx pathways. Through employing a labile mutant periplasmic protein, AcrA L222Q, it was determined that the rpoE3 mutation overcomes the ΔdegP phenotypes, in part, by activating a σ E-dependent proteolytic pathway. Our data suggest that a reduction in the OMP levels is not intrinsic to the σ E-mediated mechanism of lowering envelope stress. They also suggest that under extreme envelope stress, a tight homeostasis loop between RseA and σ E may partly be responsible for cell death, and this loop can be broken by mutations that either lower RseA activity or increase σ E levels.

UR - http://www.scopus.com/inward/record.url?scp=84858419165&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84858419165&partnerID=8YFLogxK

U2 - 10.1371/journal.pone.0033979

DO - 10.1371/journal.pone.0033979

M3 - Article

C2 - 22439016

AN - SCOPUS:84858419165

VL - 7

JO - PLoS One

JF - PLoS One

SN - 1932-6203

IS - 3

M1 - e33979

ER -